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The use of natural products obtained from plants, for example, invasive plants, offers a variety of allelochemicals with fungicidal potential. With this in perspective, the objective was to evaluate the fungicidal potential of ethanolic extracts of Cerrado plants on Rhizoctonia solani and Macrophomina phaseolina. The ethanolic hydroalcoholic extract of the 12 plants identified as invaders in the Brazilian Cerrado was prepared (Anacardium humile Saint Hill; Baccharis dracunculifolia DC.; Cenchrus echinatus L; Commelina erecta L.; Erigeron bonariensis L.; Digitaria horizontalis Willd.; Digitaria insularis L.; Porophyllum ruderale Jacq. Cass; Richardia brasiliensis Gomes; Sida rhombifolia L.; Turnera ulmifolia L.; Smilax fluminensis Steud)) and phytochemical screening and determination of total phenols and flavonoids were performed. To evaluate the in vitro antifungal activity, the hydroalcoholic solutions at concentrations of 800, 1200, 1600, 2000, and 2400 µL 100 mL-1 were separately incorporated into BDA agar and poured into Petri dishes, followed by the mycelium disk of the fungus. As a control, two solutions were prepared, one ethanolic solution added to the BDA medium (2400 µg 100 mL-1) and the other with BDA medium only. They were poured into Petri dishes, followed by a 0.5 cm diameter disk of mycelium of the fungus, incubated (23±2 ºC), with a 24-hour photoperiod. Among the constituents found in the plants, 75% are phenolic compounds, 58.3% are cardiotonic heterosides, 50% are steroids, 33.3% are flavonoids, 16.7% are anthraquinones, and 8.3% are alkaloids, saponins, and reducing sugars. Out of the 12 species, only the extracts of C. erecta and R. brasiliensis were active for M. phaseolina and R. solani. Thus, it is concluded that the ethanolic extract of C. erecta has the fungicidal potential to control diseases caused by fungi that are soil inhabitants. Of the other species, A. humille, B. dracuncufolia, D. insulares, C. erecta, D. insulares, P. ruderale, and R. brasiliensis have natural fungitoxic potential because they stand out in the content of polyphenols efficient in reducing the mycelial growth of M. phaseolina and R. solani.

O uso de produtos naturais obtidos de plantas, por exemplo, as plantas invasoras, oferece uma variedade de aleloquímicos com potencial fungicida. Tendo isso em vista, objetivou-se avaliar o potencial fungicida de extratos etanólicos de plantas do Cerrado sobre Rhizoctonia solani e Macrophomina phaseolina. Foi preparado o extrato hidroalcoólicos etanólico das 12 plantas apontadas como invasoras no Cerrado brasileiro (Anacardium humile Saint Hill; Baccharis dracunculifolia DC.; Cenchrus echinatus L; Commelina erecta L.; Erigeron bonariensis L.; Digitaria horizontalis Willd.; Digitaria insularis L.; Porophyllum ruderale Jacq. Cass; Richardia brasiliensis Gomes; Sida rhombifolia L.; Turnera ulmifolia L.; Smilax fluminensis Steud) e foi realizado o screening fitoquímico e a determinação de fenóis e flavonoides totais. Para avaliar a atividade antifúngica in vitro, as soluções hidroalcóolicas nas concentrações de 800, 1200, 1600, 2000 e 2400 µL 100 mL-1 foram incorporadas, separadamente, em ágar BDA, e vertidas em placa de Petri, seguido do disco de micélio do fungo. Como controle, foram preparadas duas soluções, uma solução etanólica adicionada ao meio BDA (2400 µg 100 mL-1), e outra somente com meio BDA, a testemunha. Foram vertidas em placas de Petri, seguido um disco de 0,5 cm de diâmetro de micélio do fungo, incubados (23±2 ºC), com fotoperíodo de 24 horas. Dentre os constituintes encontrados nas plantas, 75% estão os compostos fenólicos, 58,3% estão os heterosídeos cardiotônicos, 50% estão os esteroides, 33,3% estão os flavonoides, 16,7% estão as antraquinonas e 8,3% estão os alcaloides, saponinas e açúcares redutores. Das 12 espécies, apenas os extratos de C. erecta e R. brasiliensis foram ativos para M. phaseolina e R. solani. Desse modo, conclui-se que o extrato etanólico de C. erecta apresenta potencial fungicida para controle de doenças causadas por fungos habitantes do solo. Das demais espécies, a A. humille, B. dracuncufolia, D. insulares, C. erecta, D. insulares, P. ruderale e R. brasiliensis possuem potencial fungitóxicos naturais por destacarem nos teores de polifenóis eficientes na redução do crescimento micelial de M. phaseolina e R. solani.

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ABSTRACT Wild edible plant species can be a good source of biologically active compounds. Therefore, the aims of this research were to evaluate the antioxidant activity and quantify the phenolic compounds present in ethanolic (70% v/v) and aqueous extracts of Tinantia erecta, and to evaluate their antifungal activity against phytopathogenic fungi. The total phenol and flavonoid content and the in vitro antioxidant activity of extracts were assessed, and the phenolic compounds were quantified by HPLC. The extracts (250 µg mL-1) from T. erecta were tested for antifungal activity against Fusarium oxysporum, Phytophthora capsici, Colletotrichumgloeosporioides, Sclerotium rolfsii, and Rhizoctonia solani. The plant organ with the highest concentration of antioxidant compounds was the leaf, and the most efficient solvent for the extraction of these compounds was 70% ethanol. The phenolic compounds found in high concentrations were phloridzin (97.5 mg g-1), naringenin (19.3 mg g-1), and rutin (14.8 mg g-1). The extract obtained from leaves with 70% ethanol inhibited mycelial growth by 84 to 100%, with F. oxysporum being the least sensitive and R. solani being the most sensitive to the effect of the extract. The maximum percentage inhibition of the aqueous extracts was 15.6% against P. capsici. Extracts from the endemic species T. erecta exhibited good antioxidant activity, primarily due to the presence of phenolic compounds, and showed a great potential to inhibit phytopathogenic microorganisms.

RESUMEN Las plantas comestibles de origen silvestre pueden ser una fuente importante de compuestos biológicamente activos. Por tanto, el objetivo de la presente investigación fue evaluar la actividad antioxidante y cuantificar los compuestos fenólicos presentes en extractos etanólicos (70% v/v) y acuosos de Tinantia erecta y evaluar su actividad antifúngica frente a hongos fitopatógenos. Se evaluó el contenido de fenoles totales, flavonoides y la actividad antioxidante in vitro de los extractos, así mismo se cuantificaron los compuestos fenólicos por HPLC. También se evaluó la actividad antifúngica de los extractos (250 µg mL-1) de T. erecta frente a Fusarium oxysporum, Phytophthora capsici, Colletotrichum gloeosporioides, Sclerotium rolfsii y Rhizoctonia solani. El órgano de la planta con mayor concentración de compuestos antioxidantes fue la hoja, y el solvente más eficiente para la extracción de estos compuestos fue el etanol al 70%. Los compuestos fenólicos encontrados en más altas concentraciones fueron floridzina (97.5 mg g-1), naringenina (19.3 mg g-1) y rutina (14.8 mg g-1). El extracto obtenido de hojas con etanol al 70% inhibió el crecimiento micelial en un 84 a 100%, siendo F. oxysporum el menos sensible y R. solani el más sensible al efecto del extracto. El máximo porcentaje de inhibición de los extractos acuosos fue de tan sólo 15.6% frente a P. capsici. Los extractos de la especie endémica T. erecta exhibieron una buena actividad antioxidante, debido a la presencia de los compuestos fenólicos, así mismo mostraron un gran potencial para inhibir microorganismos fitopatógenos.

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Abstract Introducing an Absent Quarantine Pest (AQP) can cause severe economic, social and environmental impacts, generating food insecurity. The Analytical Hierarchy Process (AHP) method is an excellent tool for prioritizing APQs, allowing countries to better prepare against these threats. This study aimed to determine which AQPs should be prioritized in Brazil. For this, 20 AQPs were selected from the Brazilian official list. The selection was based on pests intercepted by Brazil between 2015 and 2018 and by countries of the European and Mediterranean Plant Protection Organization, in the international movement of plants. It can be concluded that out of the 20 AQPs studied, 17 are the priority and that the AHP method is effective for this purpose. Other countries from different continents can use this methodology to prioritize PQAs and thus create strategic plans to prevent entry into their territories and economic, social, and environmental impacts.

Resumo A introdução de uma Praga Ausente Quarentena (PQA) pode causar graves impactos econômicos, sociais e ambientais, gerando insegurança alimentar. O método Processo de Hierarquia Anal Analytical Hierarchy Process (AHP) é uma excelente ferramenta para priorizar APQs, permitindo que os países se preparem melhor contra essas ameaças. Este estudo teve como objetivo determinar quais AQPs devem ser priorizados no Brasil. Para isso, foram selecionados 20 AQPs da lista oficial brasileira. A seleção foi baseada em pragas interceptadas pelo Brasil entre 2015 e 2018 e por países da European and Mediterranean Plant Protection Organization. Pode-se concluir que dos 20 AQPs estudados, 17 são os prioritários e que o método AHP é eficaz para este fim. Outros países de diferentes continentes podem usar essa metodologia para priorizar os PQAs e, assim, criar planos estratégicos para prevenir a entrada em seus territórios e impactos econômicos, sociais e ambientais.

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RESUMEN El ARN de interferencia (ARNi) es un mecanismo evolutivamente conservado en la mayoría de las células eucariotas que permite silenciar genes mediante la degradación de ARN mensajero (ARNm) y la supresión de la síntesis de proteínas. En plantas, las moléculas de ARNi están involucradas en mecanismos de defensa contra patógenos y transposones, en la respuesta adaptativa al estrés, y en la expresión de genes relacionados con su crecimiento. El ARNi se considera una herramienta biotecnológica eficaz para silenciar la expresión de genes de microorganismos fitopatógenos, esto permite el diseño de bioplaguicidas ambientalmente seguros con una afinidad y selectividad, en muchos casos superior a la de los plaguicidas químicos. En esta revisión se señalan los últimos avances en la aplicación del ARNi en el contexto agrícola y su efectividad en el control biológico de fitopatógenos e insectos plaga. Asimismo, se presentan diversos ensayos experimentales cuyos resultados pueden ser la base para futuros bioproductos, además de algunos ejemplos disponibles en el mercado. Por último, se abordan aspectos de bioseguridad y consideraciones regulatorias necesarias para la aceptación y uso de esta tecnología a nivel global.

ABSTRACT RNA interference (RNAi) is an evolutionarily conserved mechanism in most eukaryotic cells that allows genes to be silenced by degradation of messenger RNA (mRNA) and suppression of protein synthesis. In plants, RNAi molecules are involved in defense mechanisms against pathogens and transposons, in the adaptive response to stress, and in the expression of genes related to their growth. RNAi is an effective biotechnological tool to silence the expression of specific genes which are essential for the survival of phytopathogenic microorganisms, thus allowing the design of environmentally safe biopesticides with affinity and selectivity, in many cases greater than chemical pesticides. This review describes the latest advances in the application of RNAi in the agricultural context and its effectiveness in the biological control of phytopathogens and pest insects. Likewise, various experimental trials are presented, the results of which may be the basis for future bioproducts, as well as some examples available on the market. Finally, biosafety aspects and regulatory considerations necessary for the acceptance and use of this technology at a global level are presented.

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RESUMEN Algunas especies del género Espeletia sp. (Asteraceae) son afectados por hongos fitopatógenos e insectos en páramos de los Andes del Norte, amenazando su permanencia y la prestación de servicios que se les atribuye, como la regulación del ciclo hídrico. La escaza información sobre la afectación en el páramo de Paja Blanca (Nariño, Colombia), dificulta la comprensión de la dinámica del fenómeno y la formulación de estrategias de manejo. El objetivo de esta investigación fue identificar cambios en la composición de las comunidades de insectos asociados a E. pycnophylla durante el declive de las poblaciones de frailejones y evaluar si reflejan modificaciones en los hongos, asociados a dichos insectos. Para ello, se colectaron insectos en plantas de E. pycnophylla sanas y afectadas, a los que se aplicó índices ecológicos, para identificar posibles modificaciones en la diversidad y la composición; además, se aislaron e identificaron morfológica y molecularmente hongos, a partir de estructuras corporales de los insectos. Como resultado, se identificó una diversidad de insectos considerable y que no hay modificación en su composición de insectos entre los dos estados de frailejón analizados. Se logró aislar hongos, como Fusarium oxysporum, Botrytis sp., Epicoccum nigrum, Cladosporium sp., a partir de estructuras de los géneros de insectos Neomyopites sp., Diabrotica sp., Bradysia sp. y Dyscolus sp. Este estudio aporta información sobre la entomofauna presente en E. pycnopylla del páramo de Paja Blanca y hongos asociados a estructuras corporales, como el canal alimentario y aparato bucal de los insectos.

ABSTRACT Some species of the genus Espeletia sp. (Asteraceae) are affected by phytopathogenic fungi and insects in the paramos of the Northern Andes, threatening their permanence and the provision of services attributed to them such as the regulation of the water cycle. The scarce information about the impact on the Paja Blanca páramo (Nariño, Colombia) makes it difficult to understand the dynamics of the phenomenon and the formulation of management strategies. The goal of this research was to identify changes in the composition of the insect communities associated to E. pycnophylla during the decline of the frailejon populations and to evaluate if these reflect modifications in the fungi associated with those insects. For this, insects were collected in healthy and affected E. pycnophylla plants to which ecological indices were applied to identify possible changes in diversity and composition, Also fungi were isolated and identified morphologically and molecularly from body structures of insects. As result, a considerable diversity of insects was identified and no modification in their composition of insects between the two states of frailejón were found. It was possible to isolate fungi such as Fusarium oxysporum, Botrytis sp., Epicoccum nigrum, Cladosporium sp. from structures of the insect genera Neomyopites sp., Diabrotica sp., Bradysia sp. and Dyscolus sp. This study provides information about the entomofauna present in E. pycnopylla from the Paja Blanca páramo and fungi associated with body structures such as the alimentary canal and the oral system of insects.

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Introducción. Las susceptibilidades de las plantaciones al ataque de organismos dañinos pueden ocasionar efectos nocivos para su desarrollo, cuando se considera que el nivel de daños ocasionado no se puede tolerar, es indispensable determinar acertadamente la naturaleza del agente causal, sea éste tipo biótico o abiótico; la acertada determinación del agente de un problema fitosanitario en un vivero o plantaciones forestale, se fundamenta en un análisis detallado de los factores que la pueden estar afectando. Tabebuia rosea o Guayacán rosado es una especie forestal nativa de amplia aceptación en el mercado, que presenta durante su etapa de vivero, limitantes en las fases de germinación, emergencia y sobrevivencia, por lo anterior el objetivo de esta investigación era la de Identificar morfológicamente los posibles agentes patógenos asociados a Tabebuia rosea en etapa de vivero y comprobar su patogenicidad. Metodología. Se tomaron plántulas de vivero, las cuales se les realizo un análisis de los signos y los síntomas para el aislamiento y siembra de zonas afectadas en agar papa dextrosa. En el cultivo mixto se identificó los posibles agentes patógenos, los cuales fueron sembrados para obtener cultivos puros, y utilizados en la prueba de patogenicidad, para la inoculación de las estructuras sanas (hojas, peciolos y tallos) y su respectivo control. Resultados. Se identificaron tres géneros de hongos Colletotrichum, Mucor, y Candida, y un género de nematodo denominado Meloidogyne. La prueba de patogenicidad para Colletotrichum y Candida mostraron relaciones significativas en el proceso de infección principalmente en estructuras foliares. Se concluye en este trabajo dos nuevos posibles géneros patógenos para Tabebuia rosea evidenciados en la prueba de patogenicidad. Y se corrobora que el género Meloidogyne es un patógeno severo en el guayacán rosado que ocasiona anomalías morfológicas en la raíz; cabe resaltar que es el primer reporte para el departamento de Risaralda

Introduction. The susceptibilities of plantations to attack by harmful organisms can cause harmful effects for their development, when it is considered that the level of damage caused cannot be tolerated, it is essential to correctly determine the nature of the causal agent, be it biotic or abiotic; The correct determination of the agent of a phytosanitary problem in a nursery or forest plantations is based on a detailed analysis of the factors that may be affecting it. Tabebuia rosea or pink Guayacán is a native forest species widely accepted in the market, which presents, during its nursery stage, limitations in the germination, emergence and survival phases, therefore the objective of this research was to morphologically identify the possible pathogens associated with Tabebuia rosea in the nursery stage and check its pathogenicity. Methodology. Nursery seedlings were taken, which were analyzed for signs and symptoms for the isolation and sowing of affected areas on potato dextrose agar. In the mixed culture, possible pathogens were identified, which were sown to obtain pure cultures, and used in the pathogenicity test, for the inoculation of healthy structures (leaves, petioles and stems) and their respective control. Results. Three fungal genera Colletotrichum, Mucor, and Candida, and a nematode genus named Meloidogyne were identified. The pathogenicity test for Colletotrichum and Candida showed significant relationships in the infection process mainly in leaf structures. Two new possible pathogenic genera for Tabebuia rosea evidenced in the pathogenicity test are concluded in this work. And it is corroborated that the genus Meloidogyne is a severe pathogen in the pink guayacán that causes morphological anomalies in the root; It should be noted that it is the first report for the department of Risaralda

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Chemicals are often used in attempts to control diseases caused by plant pathogenic fungi during food production. However, chemicals can have adverse effects not just on food, but they also remain active for a long time within ecosystems, and thus are not environmentally friendly. Therefore,development of bio-treatment and avoiding use of chemicals are urgently needed. With the aim of studying and developing new environmentally-friendly treatments, we tested extracts from selected bryophyte species(Porella platyphylla, Cinclidotus fontinaloides and Anomodon viticulosus) on five plant pathogenic fungi under controlled conditions. The fungi (Botryosphaeria dothidea, Phomopsis viticola, Calosphaeria sp., Colletotrichum acutatum and Monilinia laxa) were selected based on common diseases they cause on fruits and grapevine. They were isolated in cultures and treated with bryophyte extracts. Bryophyte extracts were shown to be effective in suppression of certain plant pathogenic fungi growth and to have a huge potential in development of novel biotechnological treatments and biofungicides. The best results were achieved in inhibition of B. dothidea, P. viticola and Calosphaeria sp.

Fungos fitopatogênicos são controlados com produtos químicos para combater doenças causadas por eles durante a produção de alimentos. Tais produtos são ruins não apenas para a alimentação, mas também podem permanecer por muito tempo nos ecossistemas, portanto, não são ecologicamente corretos. Desta forma, os biotratamentos e a prevenção de usos químicos são urgentemente necessários no futuro próximo. Com o objetivo de estudar e desenvolver nova alternative decontrole de doenças de plantas, testamos os extratos de espécies de briófitas selecionadas (Porella platyphylla, Cinclidotus fontinaloides e Anomodon viticulosus) em cinco fungos fitopatogênicos (Botryosphaeria dothidea, Phomopsis viticola, Calosphaeria sp., Colletotrichum acutatum e Monilinia laxa) em condição controlada. Estes fungos, selecionados com base nas doenças que causam em frutos e videiras, foram isolados em culturas puras e tratados com os respectivos extratos de briófitas. Os extratos de briófitas demonstraram ser eficazes na supressão de certos fungos fitopatogênicos e têm um enorme potencial no desenvolvimento de novos biofungicidas e tratamentos biotecnológicos. Os mais interessantes resultados foram obtidos na inibição de B. dothidea, P. viticola eCalosphaeria sp.

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Los líquenes son producto de una asociación simbiótica entre un hongo y alga y/o cianobacteria; esta simbiosis produce una serie de metabolitos secundarios o sustancias liquénicas únicas, las mismas que son aisladas a partir de sus extractos y que han presentado una marcada actividad antibiótica y antifúngica. Considerando que en el Ecuador no se tienen antecedentes acerca de este tipo de estudios, el objetivo planteado fue el evaluar la actividad antifúngica del extracto liquénico de Usnea laevis frente a hongos fitopatógenos. En el presente estudio las sustancias liquénicas almacenadas en el talo de Usnea laevis fueron extraídas con metanol y etanol. La actividad antifúngica in vitro de estos extractos fue probado frente a géneros de hongos fitopatógenos previamente aislados (Aspergillus, Penicillium y Rhizopus stolonifer); añadiéndolo al medio de cultivo Agar Papa Dextrosa (PDA) a una concentración de 0,5%; determinándose el porcentaje de inhibición. Los datos fueron analizados estadísticamente y se realizó la clasificación del extracto en base a su porcentaje de inhibición según la OILB. El extracto metanólico y etanólico de Usnea laevis mostró una mayor efectividad frente a Rhizopus stolonifer, inhibiendo más del 50% de su crecimiento, a diferencia de Penicillium y Aspergillus cuyo porcentaje de inhibición fue mucho menor y mostraron diferencias estadísticamente significativas. El extracto liquénico fue moderadamente tóxico para Rhizopus stolonifer, ligeramente tóxico para Aspergillus sp 1 y Penicillium sp e inocuo para Aspergillus sp 2.

A lichen is an organism product of a symbiotic association between a fungus and algae and / or cyanobacteria; this symbiosis produces many secondary metabolites or unique lichen substances, which are isolated from their extracts and show a marked antibiotic and antifungal activity. Considering there is no background on this type of studies in Ecuador, the aim of this study was to evaluate the antifungal in vitro activity of Usnea laevis extract on phytopathogenic fungi. The lichenic substances stored in the thallus of Usnea laevis were extracted with methanol and ethanol. The in vitro antifungal activity of these extracts was tested against phytopathogenic fungal genera previously isolated (Aspergillus, Penicillium and Rhizopus stolonifer) . They were adding to Potato Dextrose Agar (PDA) culture medium at a concentration of 0.5%, and the inhibition percentage was determined. Data were statistically analyzed and the extract was classified based on its inhibition percentage according to the OILB. Methanolic and ethanolic extracts of Usnea laevis showed greater effectiveness against Rhizopus stolonifer, inhibiting more than 50% of its growth, unlike Penicillium and Aspergillus, whose inhibition percentage was lower and showed significant differences. The liquid extract was also moderately toxic to Rhizopus stolonifer, slightly toxic to Aspergillus sp 1 and Penicillium sp and harmless to Aspergillus sp 2.

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Resumen Objetivo. Identificar microorganismos fitopatógenos presentes en las aguas utilizadas para riego en la cuenca media del rio Bogotá. Métodos. Las muestras fueron tomadas en doce fincas de la cuenca media y analizadas con la técnica de filtración por membrana. Las bacterias se identificaron por bioquímica y los hongos por claves dicotomas. Resultados. El agua de riego analizada contenía bacterias como: E.coli, P. vulgaris, A. urinae, E. cloacae, B.cereus, S. marcescens, B. brevis, y en cuanto a los hongos se encontraron: Aspergillus fumigatus, Aspergillus flavus., Mucor sp., Rhizopus sp., Penicillium sp. y Fusarium sp. La presencia de estos potenciales fitopatógenos en el agua indican un alto riesgo de contaminación y dispersión de éstos en los cultivos.

Abstract Objective. Identify phytopathogenic microorganisms present in the water used for irrigation in the middle basin of the river Bogota. Methods. Samples were taken at 12 farms of the middle basin and analyzed by the membrane filtration technique. The bacteria were identified by biochemical and fungi by dichotomies keys. Results. The irrigation water contained bacteria analyzed as E. coli, P. vulgaris, A. urinae, E. cloacae, B. cereus, S. marcescens, B. brevis, and as for the mushrooms found: A. fumigatus, A. flavus, Mucor sp., Rhizopus sp., Penicillium sp. and Fusarium sp. The presence of these potential pathogens in water indicate a high risk of contamination and dispersion thereof in crops.

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El objetivo de este estudio fue caracterizar y evaluar in vitro la eficiencia del aceite esencial foliar de Lippia alba contra Colletotrichum gloeosporioides. Se extrajo el aceite esencial a partir de las hojas mediante el método de hidrodestilación asistida por microondas (MWHD) y se identificaron sus metabolitos mediante una cromatografía de gases acoplada a espectrometría de masas (GC/MS). La evaluación in vitro se realizó empleando 4 concentraciones del aceite esencial (500, 1000, 3000 y 10000 ppm) diluidas en acetona; se utilizó un control positivo con Benomil 1 g/L, un control negativo con acetona y un testigo absoluto; la eficiencia del aceite se midió mediante el porcentaje de índice antifúngico (%I.A). El componente mayoritario en el aceite esencial fue el citral (34.62 a 40.03%) y que el mayor %I.A se encontró a la concentración de 10000 ppm (97.8%), muy similar a la del Benomil (100%). Lo anterior demostraría la eficacia del aceite esencial de L. alba para controlar a C. gloeosporioides, y su posible uso como fungicida biológico.

The aim of this study was to characterize and evaluate the in vitro efficiency of leaf essential oil of Lippia alba against Colletotrichum gloeosporioides. Essential oil from the leaves was extracted by the method of assisted microwave hydrodistillation (MWHD) and metabolites were identified by gas chromatography coupled to mass spectrometry (GC/ MS). The in vitro evaluation was performed using 4 concentrations of essential oil (500, 1000, 3000 and 10000 ppm) diluted in acetone; positive control with Benomyl 1 g /L, a negative control with acetone and absolute control was used; oil efficiency was measured by the percentage of antifungal index (% IA). It was found that the major component was in the essential oil citral (34.62 to 40.03%) and the highest %I.A was found to 10000 ppm concentration (97.8%) very similar to Benomyl (100%). This would demonstrate the efficacy of the L. alba essential oil to control C. gloeosporioides, and its possible use as a biological fungicide.

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El hongo Macrophomina phaseolina (Tassi) Goid., agente causal de la enfermedad denominada «pudrición carbonosa¼, provoca pérdidas significativas en la producción de cultivos como maíz, sorgo, soya y frijol en México. Este hongo, parásito facultativo, muestra amplia capacidad de adaptación a ambientes estresantes, donde existen altas temperaturas y deficiencia hídrica, condiciones frecuentes en gran parte de la agricultura de dicho país. En este trabajo se describen algunos aspectos básicos de la etiología y la epidemiología de M. phaseolina. Asimismo, se revisa la importancia que guardan las respuestas de este hongo a ambientes estresantes, particularmente la deficiencia hídrica, de acuerdo con caracteres morfológicos y del crecimiento, así como fisiológicos, bioquímicos y de patogenicidad. Finalmente, se presentan algunas perspectivas de estudio del género, que enfatizan la necesidad de mejorar su conocimiento, con base en la aplicación de herramientas tradicionales y de biotecnología, y de dilucidar mecanismos de tolerancia al estrés ambiental, extrapolables a otros microorganismos útiles al hombre.

Fungus Macrophomina phaseolina (Tassi) Goid. is the causative agent of charcoal rot disease which causes significant yield losses in major crops such as maize, sorghum, soybean and common beans in Mexico. This fungus is a facultative parasite which shows broad ability to adapt itself to stressed environments where water deficits and/or high temperature stresses commonly occur. These environmental conditions are common for most cultivable lands throughout Mexico. Here we describe some basic facts related to the etiology and epidemiology of the fungus as well as to the importance of responses to stressed environments, particularly to water deficits, based on morphology and growth traits, as well as on physiology, biochemistry and pathogenicity of fungus M. phaseolina. To conclude, we show some perspectives related to future research into the genus, which emphasize the increasing need to improve the knowledge based on the application of both traditional and biotechnological tools in order to elucidate the mechanisms of resistance to environmental stress which can be extrapolated to other useful organisms to man.

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Fungus Macrophomina phaseolina (Tassi) Goid. is the causative agent of charcoal rot disease which causes significant yield losses in major crops such as maize, sorghum, soybean and common beans in Mexico. This fungus is a facultative parasite which shows broad ability to adapt itself to stressed environments where water deficits and/or high temperature stresses commonly occur. These environmental conditions are common for most cultivable lands throughout Mexico. Here we describe some basic facts related to the etiology and epidemiology of the fungus as well as to the importance of responses to stressed environments, particularly to water deficits, based on morphology and growth traits, as well as on physiology, biochemistry and pathogenicity of fungus M. phaseolina. To conclude, we show some perspectives related to future research into the genus, which emphasize the increasing need to improve the knowledge based on the application of both traditional and biotechnological tools in order to elucidate the mechanisms of resistance to environmental stress which can be extrapolated to other useful organisms to man.

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ABSTRACT Recent research reports the importance of preserving plants in Brazilian semiarid regions, in this context, the scientific literature has reported different pharmacological studies from plant extracts with an antifungal potential, coming from forest species that can contribute as a control and management strategy in the transmission of phytopathogens. This study aimed to evaluate the effect of biotech treatments in controlling the transmission of Colletotrichum sp. in seeds of S. obtusifolium. In this study, 100 seeds were subjected to the following preventive treatments: fungicide Captan®, extract of Caesalpinia ferrea Mart. Ex. Tul., and biological control with Trichoderma spp. The biological control with Trichoderma spp. and the alternative control using C. ferrea extract provided a greater protection to seeds and seedlings of S. obtusifolium facing the transmissibility of Colletotrichum sp.The treatment based on plant extract is more efficient for this purpose only in large seeds and does not interfere on the germination percentage and speed. Therefore it is necessary to perform other studies with Trichoderma spp. and C. ferrea extract to test different doses of these products.

RESUMO Recentes pesquisas relatam a importância da preservação de plantas do semiárido brasileiro. Neste contexto, a literatura científica tem relatado diferentes estudos farmacológicos com extratos vegetais com potencial antifúngico proveniente de espécies florestais que podem contribuir como estratégia de controle e gerenciamento na transmissão de fitopatógenos. No presente estudo o objetivo foi avaliar o efeito de tratamentos biotecnológicos no controle da transmissibilidade de Colletotrichum sp. em sementes de S. obtusifolium. Neste estudo foram utilizadas 100 sementes submetidas aos seguintes tratamentos preventivos: fungicida Captan®, extrato de Caesalpinia ferrea Mart. Ex. Tul. e controle biológico com Trichoderma spp. O controle biológico com Trichoderma spp. e o alternativo com extrato de C. ferrea proporcionam maior proteção às sementes e plântulas S. obtusifolium quanto a transmissibilidade do Colletotrichum sp. O tratamento à base de extrato vegetal foi o mais eficiente para este fim, apenas em sementes de maior tamanho, por não interferir na porcentagem e velocidade de germinação. Portanto, faz-se necessário à realização de outros trabalhos com Trichoderma spp. e extrato de C. ferrea para testar doses diferentes desses produtos.

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Los productos naturales son una alternativa para el control de microorganismos que ocasionan enfermedades en los cultivos. Este trabajo tuvo como objetivo evaluar diferentes solventes para la obtención de extractos crudos a partir de exudados foliares de líneas de tabaco, y el efecto in vitro de estos extractos contra dos bacterias fitopatógenas: Xanthomonas campestris (Xc) y Pectobacterium carotovorum (Pc). Se evaluaron solventes con polaridades entre 3.1 y 6.2 (diclorometano, n-butanol, acetato de etilo, metanol y etanol 90 %). El etanol 90 % se seleccionó como mejor solvente y como sustituto del diclorometano por su mayor rendimiento. Los extractos etanólicos crudos se obtuvieron a partir de exudados foliares de diez líneas de tabaco seleccionadas. La diversidad de la composición química de los extractos etanólicos se reveló por cromatografía en capa delgada. La actividad antibacteriana se evaluó por el método de difusión en agar con discos de papel de filtro y la medición del diámetro del halo de inhibición. Se observó inhibición para todos los extractos contra Xc destacándose los correspondientes a las líneas Nic 1061 "TI 1738" y Nic 1016 "Incekara" hasta 5 µg de extracto crudo seco /disco, con un mayor rendimiento para la línea Nic 1061. El extracto de la línea Nic 1015 fue el único con actividad contra Pc hasta 5 µg de extracto crudo seco por disco. Estos resultados sugieren un uso potencial de los extractos crudos de las líneas Nic 1061 y Nic 1015 "TI 1341" como un agente efectivo para la protección de cultivos contra estas bacterias.

Natural products are an alternative to control microorganisms that cause diseases in crops. This work aimed to evaluate different solvents for obtaining crude extracts from tobacco leaf exudates and to determine in vitro effect of these extracts against two phytopathogenic bacteria: Xanthomonas campestris(Xc) and Pectobacterium carotovorum(Pc). Crude extracts from ten tobacco lines using solvents with polarities between 3.1 and 6.2 (dichloromethane, n-butanol, ethyl acetate, methanol and ethanol 90%) were obtained. Ethanol 90% was selected as the best solvent for obtaining extracts from tobacco leaf exudates and as a substitute of dichloromethane due to the best yield. The chemical composition diversity of the ethanolic extracts was revealed by thin-layer chromatography. The antibacterial activity was evaluated by agar disk diffusion method recording the inhibition zones. Growth inhibition was observed for all extracts against Xc, and the better activity corresponded to the lines Nic 1061"TI 1738" and Nic 1016 "Incekara" until a minimal amount of 5 µg/ disc, with higher yield in case of the line Nic1061 . Only the extract of the line Nic 1015 was able to inhibit the growth of Pc until a minimal inhibitory concentration of 5 µg/disc. These results suggest a potential use of crude extracts from lines Nic 1061 and Nic 1015 "TI 1341" as an effective agent for the crop protection against Xc and Pc respectively.

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Objetivou-se avaliar a ação de diferentes concentrações de óleos essenciais de três plantas medicinais sobre o crescimento micelial, a produção e a germinação de conídios de Colletotrichum gloeosporioides (Penz.). Utilizou-se os óleos essenciais de Lippia sidoides Cham., Cymbopogon citratus (DC) Stapf.) e Ocimum gratissimum L. em cinco concentrações (0 µL mL-1, 1 µL mL-1, 3 µL mL-1, 5 µL mL-1 e 7 µL mL-1) com 4 repetições no delineamento inteiramente casualizado, em esquema fatorial 5x3. Os óleos foram analisados por cromatografia gasosa acoplada com espectrometria de massas. Para todas as características verificou-se efeito significativo da interação "Óleo" versus "Concentração". O óleo essencial de C. citratus proporcionou a maior inibição do crescimento micelial em todas as concentrações testadas. Os outros óleos não se diferenciaram, exceto a partir da concentração de 5 µL mL-1, onde o óleo de L. sidoides foi superior ao óleo de O. gratissimum. Na produção e germinação de conídios, o óleo de C. citratus, foi superior aos óleos de L. sidoides e de O. gratissimum nas concentrações de 1 µL mL-1 e 3 µL mL-1, inibindo completamente a produção e germinação a partir da concentração de 3 µL mL-1. As concentrações influenciam em todas as variáveis, ajustando-se à equação do modelo linear. Observa-se o decréscimo nessas, à medida em que se aumentam as concentrações dos óleos testados. Os óleos essenciais testados possuem efeito fungitóxico e fungistático.

The objective of this study was to evaluate the action of different concentrations of essential oils of three medicinal plants on the mycelial growth, production and conidial germination of Colletotrichum gloeosporioides (Penz.). We used a completely randomized design, in a 5x3 factorial design, being five concentrations (0 µL mL-1, 1 µL mL-1, 3 µL mL-1, 5 µL mL-1 e 7 µL mL-1) x three oils from Lippia sidoides Cham., Cymbopogon citratus (DC) Stapf. and Ocimum gratissimum L., with four replications. The oils were analyzed by gas chromatography with mass spectrometry. There was a significant interaction of concentration versus species on all analyzed traits. The essential oil from C. citratus yielded the highest mycelial growth inhibition at all concentrations. The other oils were not differentiated, except at the concentration of 5µL mL-1, in which the oil of L. sidoides was more efficient that the oil of O. gratissimum. In conidial production and germination, the oil of C. citratus was superior to the oil of L. sidoides and O. gratissimum at the concentrations of 1 µL mL-1 and 3 µL mL-1, as it completely inhibited the production and germination of conidia at the concentrations of 3 µL mL-1 and above. The concentrations influenced all the variables, adjusting themselves to the linear model equation. We observed a decrease in the variables, as the concentrations of the oils tested are increased. The essential oils used have antifungal and fungicidal effect.

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As proteínas inibidoras de poligalacturonases (PGIPs) presentes na parede celular são capazes de limitar o potencial destrutivo da poligalacturonase (PG) fúngica e, assim, constituem um tipo importante dentre os diversos sistemas de defesa do tecido vegetal frente à infecção fúngica. No mamão, o ataque fitopatogênico é o principal causador de danos pós-colheita, e sua alta susceptibilidade pode estar relacionada com a baixa eficácia ou pouca abundância dos meios de defesa anti-fitopatogênica. Uma vez que isso pode estar relacionado com as PGIPs e nada se conhece sobre o papel dessas proteínas nesse fruto, o objetivo do trabalho foi clonar os genes das PGIPs de mamoeiro e definir seu padrão de expressão em diferentes órgãos e tecidos e ao longo do amadurecimento. Para tanto, foram identificadas no genoma do mamoeiro, a partir de critérios que definem a identidade de uma PGIP, duas prováveis sequências dentre 13 candidatas iniciais. Ambas foram clonadas a partir das sequências genômicas e de cDNA, sequenciadas e sua identidade confirmada, sendo denominadas Cppgip4 e Cppgip6. As análises de expressão relativa em diversos tecidos e idades fisiológicas do mamoeiro demonstraram que os dois genes apresentaram diminuição da expressão com o desenvolvimento dos frutos, sendo que com a polpa apresentou redução dos níveis de expressão relativa de Cppgip4 em até 18 vezes dos 30 dias pós-antese (DPA) ao 9 dias pós-colheita (DPC). Na casca também houve redução significativa da expressão com o desenvolvimento. Para a expressão absoluta, nos frutos, sementes, caules, raízes e folhas, o número de cópias de ambos os transcritos decresceu com o desenvolvimento, sendo cerca de cem mil vezes mais abundante para Cppgip6 que para Cppgip4. As tentativas de expressão de proteínas recombinantes em Pichia pastoris não geraram resultado positivo, provavelmente em virtude das condições ideais de indução ainda não terem sido estabelecidas corretamente para o ensaio. A atividade de PGIPs extraídas diretamente do tecido foi medida por análise de difusão em ágar empregando pectinase de Aspergillus niger e revelou uma tendência à diminuição da porcentagem de inibição à medida que os frutos se desenvolveram, em concordância com os resultados da análise por qPCR. O conjunto de resultados sugere que a expressão varia com o estádio de desenvolvimento do fruto e é tecido-específica, possivelmente em resposta à diferente susceptibilidade dos tecidos ao ataque fitopatogênico, indicando que menores níveis de transcritos e atividade no amadurecimento, período de maior susceptibilidade, poderiam sinalizar para a regulação do processo degradativo marcando o início da senescência

Polygalacturonase inhibiting proteins (PGIPs) present in plant cell walls are able to inhibit the destructive action of fungal polygalacturonase (PG). In this way, they constitute an important type of plant defense system against fungal infections. In papaya fruit, the pathogenic attack is the main cause of post harvesting loss, and its high susceptibility may be related to the low efficiency or low abundance of anti-phytopathogenic defense. Since this fact could be related to PGIPs expression and little is known about the response of these proteins in the fruit, the aim of the present work was to clone the genes of PGIPs papaya fruit and set their expression pattern in different organs and tissues throughout fruit ripening. Thus, two probable PGIP sequences among 13 initial candidates were identified in the papaya genome by using specific criteria. Both sequences were cloned from cDNA and genomic samples, sequenced and confirmed its identity, and then being named Cppgip4 and Cppgip6. Analysis of relative expression in various tissues at different physiological stages demonstrated that both genes were down regulated during fruit development. The relative expression levels of Cppgip4 in papaya pulp was reduced by 18 times from the 30 days post-anthesis (DPA) to the 9 days post-harvest (DPH). Similarly, gene expression in papaya peel was significant down regulated during fruit development. Absolute expression analysis revealed gene expressions in the fruit pulp, seed, stem, root and leaf were also down regulated within development. Moreover, Cppgip6 gene expression was a hundred thousand times more abundant than Cppgip4. The recombinant protein expression in Pichia pastoris did not result positive, probably because of the ideal conditions of induction have not been properly established the yet. The activity of PGIPs extracted directly from the tissue was measured by the agar diffusion assay using pectinase from Aspergillus niger and showed decrease of inhibition during fruit developed in accordance with the results of the qPCR analysis. Based on the results it is possible to suggest the expression of these genes varies temporally with the developmental stage of the fruit and is tissue-specific, possibly in response to the different susceptibility of tissues to pathogenic attack. In addition, the lowest levels of PGIP expression were achieved at the fruit ripening, when the susceptibility to fungal infection is high and could signal for regulating the degradation process characterized by the onset of senescence

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Métodos alternativos para o controle de doenças e pragas de plantas vêm sendo pesquisados buscando causar menores danos ao ambiente e a saúde humana. Diante disso, o objetivo deste estudo foi identificar extratos de plantas e óleos essenciais com possíveis efeitos sobre Phakopsora pachyrhizi, agente etiológico da ferrugem-asiática da soja. Assim, 61 extratos de plantas da flora nativa da região do Alto Rio Grande, Minas Gerais e cinco óleos essenciais obtidos comercialmente foram utilizados com a finalidade de testar os efeitos na germinação de urediniósporos do referido fungo. Foram utilizadas placas de Petri de 6 cm, com meio ágar-água, adicionado com 150 µL de extrato de planta ou 6 µL do óleo essencial misturado ao meio de cultura. Como testemunhas foram utilizadas 150 µL de Tween 20 a 0,7% e 150 µL de água destilada. Após, foram adicionados 50µL de uma suspensão de urediniósporos, na concentração de 2mg.5mL-1 e espalhados com alça de Drigalsky. As placas foram colocadas em BOD, a 23(±2ºC), por 4 horas. A germinação foi paralisada com adição de lactoglicerol. A avaliação da percentagem de esporos germinados foi realizada em microscópio de luz. Dentre os extratos vegetais testados, dez apresentaram percentual de germinação abaixo de 15%, tendo os extratos obtidos das plantas Pelargonium sp., Salvia officinalis, Lavandula officinalis, Mentha pulegium e M. arvensis apresentado germinação de esporos de 3,0%, 3,5%, 3,0%, 2,0% e 4,0%, respectivamente. Todos os óleos essenciais avaliados foram efetivos na inibição da germinação, com destaque para o óleo essencial de Caryophilus aromaticus, que apresentou percentagem de germinação de 5%, resultando num percentual de inibição de 50,0%.

Alternative methods to control plant diseases and plagues have been studied, in order to cause less damages to the environment and human health. The purpose of this study was to identify plant extracts and essential oils as possible alternative products that affect the urediniospore germination of Phakopsora pachyrhizi, the causal agent of the Asian soybean rust. Plant extracts (61) from the native flora of the Alto Rio Grande region, State of Minas Gerais, Brazil, as well as five commercial essential oils were used with the purpose of testing their effects on the germination of urediniospores of the referred fungus. 6cm Petri dishes were used, with water-agar medium, added with 150 µL of plant extract or 6 µL of essential oil mixed to the culture medium. As control, 150 µL of Tween 20 at 0.7% and 150 µL of distilled water were used. Then, 50 µL of a suspension of urediniospores were added, at a concentration of 2mg5mL-1 and spread with Drigalsky spatula. Then, the plates were put in BOD, at 23(±2ºC), for 4 hours. Germination was paralyzed by adding lactoglicerol. The percentage of spore germination was evaluated in a light microscope. Among the vegetal extracts tested, ten of them presented a germination percentage below 15%. The extracts from the Pelargonium sp., Salvia officinalis, Lavandula officinalis, Mentha pulegium and M. arvensis plants presented 3.0%, 3.5%, 3.0%, 2.0% and 4.0% of urediniospore germination, respectively. All the essential oils evaluated were effective in inhibiting germination, especially the Caryophilus aromaticus essential oil that presented 5.0% of germination, with 50.0% of inhibition.

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Se aislaron e identificaron los hongos presentes en granos de arroz manchados, de la variedad INCA LP-5, cosechados durante las épocas lluviosas de los años 2003 y 2005, en áreas de la Estación Experimental del Arroz “Los Palacios”, Pinar del Río, perteneciente al Instituto Nacional de Ciencias Agrícolas (INCA). Se determinó la incidencia y se realizaron las pruebas de patogenicidad mediante los postulados de Koch. Se identificaron 35 especies, correspondientes a 19 géneros de hongos asociados a granos manchados de la variedad INCA LP-5, y entre ellas se señalaron, como nuevos registros asociados al manchado del grano de arroz para Cuba a: Bipolaris maydis, Fusarium merismoides, F. solani, F. subglutinans, Penicillium itallicum, Phoma medicaginis var. pinodella y Syncephalastrum racemosum. Los hongos de mayor incidencia fueron Bipolaris oryzae, Sarocladium oryzae y especies de los géneros Alternaria, Fusarium, Curvularia y Phoma. Se confirmó que los hongos F. subglutinans, B. oryzae, A. padwickii, Alternaria sp., F. verticillioides, C. lunata, C. lunata var. aeria, C. pallescens, C. senegalensis, Curvularia sp., Phoma sp. y S. oryzae, son agentes causales del manchado del grano de arroz.

Isolation and identification of the fungi present in spotted rice grains of the INC LP-5 variety, harvested during the rainy seasons of the years 2003 and 2005, was done at sites of the Experimental Rice Station “Los Palacios”, Pinar del Río, belonging to the Instituto Nacional de Ciencias Agrícolas (INCA). Incidence was determined, and pathogenicity tests were carried out according to Koch’s postulates. Thirty-five species corresponding to 19 fungi genus associated to spotted grains of the INCA-LP-5 variety were identified, and among them, the following strains were indicated as new registrations associated to spotting of rice grains in Cuba: Bipolaris maydis, Fusarium merismoides, F. solani, F. subglutinans, Penicillium itallicum, Phoma medicaginis var. pinodella and Syncephalastrum racemosum. The fungi with the highest incidence were Bipolaris oryzae, Sarocladium oryzae and species of the genus Alternaria, Fusarium, Curvularia and Phoma. It was confirmed that the fungi F. subglutinans, B. oryzae, A. padwickii, Alternaria sp., F verticilloides, C. lunata, C.lunata var. aeria, C. pallescens, C. senegalensis, Curvularia sp., and S. oryzae, are causative agents of the spotting of rice grains.

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Tomando en consideración el efecto adverso que provocan los pesticidas al medio ambiente y la salud y la posibilidad de al menos minimizar su uso, se investigó el efecto del control biológico de tres antagonistas microbianos (Trichoderma viride, Pseudomonas aeruginosa y Bacillus subtilis), sobre fitopatógenos causantes de enfermedades en vegetales como: tomate, cebolla y pimentón. Los ensayos se realizaron en semillas de estos tres rubros infectadas experimentalmente con tres fitopatógenos (Phytophthora spp, Fusarium monilliforme y Rhyzoctonia solani). Inicialmente, el efecto de los antagonistas sobre los fitopatógenos se determinó en medios de cultivo Sabouraud sólido (agar) y líquido (caldo). Posteriormente, 35 semillas de cada una de las especies vegetales seleccionadas se sometieron a diferentes tratamientos: I-Grupo control, sin ninguna adición; II-Grupo tratado con los antagonistas y III-Grupo infectado con los fitopatógenos. Todos los grupos se sembraron en tierra abonada, a cielo abierto y a temperatura ambiente y regados dos veces diariamente con agua. Adicionalmente, al grupo III se le agregó diariamente un inóculo de 0,1 mL de antagonista (10(4) UFC/mL). El desarrollo de las plantas se monitoreo por dos semanas determinándose el número de semillas germinadas, la longitud de las plántulas y el follaje. Los resultados se analizaron a través de Statistix 8.0, pruebas Tukey y Kruskal-wallis. Los antagonistas inhibieron la proliferación de los fitopatógenos en medio Sabouraud. Los experimentos con semillas demostraron una mayor estimulación de la germinación y tamaño de las plántulas en el grupo tratado con fitopatógenos y antagonistas respecto al grupo control (p<0,1).

Taking in account the negative actions of pesticides exert on natural environment and health and due to the possibility to minimize/eliminate its use, the effect of microbial antagonist (Trichoderma viride, Pseudomonas aeruginosa and Bacillus subtilis), were evaluated on tomato, onion and pimento seeds experimentally infected with three known phytopatogens (Phytophthora spp, Fusarium monilliforme and Rhyzoctonia solani). Initially, the antagonist effect on the phytopatogens were studied on Sabouraud solid (agar) and liquid (broth) media. Further 35 seeds of each vegetable were treated according to the following experimented protocol group I (control): no addition and water, group II (treated): antagonist and water, group III (infected): antagonist, water and phytopathogens. All groups were grown on soil, under sun light, at room temperature and water was added twice a day. Group III was daily infected with 0,1 mL of the antagonist suspensions (10(4) UFC/mL). The plant development was followed for 2 weeks, determining number of germinated seeds (germination index), plantule length and foliage. The results obtained was analyzed with Statistix 8.0, Tukey and Kruskal-Wallis. The antagonist inhibited the proliferation of the phytopathogens in Sabouraud media. The seed treated and infected showed a higher index of germination and plantule respect to the control and treated groups (p<0,1).

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RESUMEN Las plantas, al igual que todos los organismos de la naturaleza, poseen elaborados sistemas de defensa contra patógenos, que pueden ser físicos y químicos, y producirse de forma constitutiva e inducida. Dentro de las barreras químicas inducidas se encuentra el grupo de proteínas de bajo peso molecular denominadas péptidos antimicrobianos (AMPs), al cual pertenecen las defensinas, péptidos con peso molecular entre 5 a 7 kDa, punto isoeléctrico de 9, y longitud de 45 a 55 aminoácidos; que tienen la capacidad de inhibir efectivamente el crecimiento de microorganismos fitopatógenos, en su mayoría hongos, y además, generan resistencia a condiciones abióticas de estrés en plantas. Este texto pretende realizar una descripción clara y actual de las características e investigaciones recientes con relación a las defensinas de plantas y sus más destacados usos en el control de patógenos en cultivos de importancia económica. Se plantea además la necesidad de profundizar en el conocimiento de dichas proteínas para su uso en estrategias de control tales como la producción de plantas y microorganismos transgénicos.

ABSTRACT Plants, as all organisms in nature, have elaborate systems of defense against pathogens; which can be physical or chemical and produced in a constitutive and induced way. Among the induced chemical barriers, there is a group of low molecular weight proteins, known as antimicrobial peptides (AMPs). These peptides include defensins, which are peptides with a molecular weight about 5 to 7 kDa, isoelectric point of 9, and length of about 45 to 55 amino acids. Likewise, they have the ability to avoid the growth of phytopathogenic microorganisms, mainly funguses. Moreover, these peptides create resistance to abiotic conditions of stress in plants. This manuscript seeks to make a clear and current description about the recent characteristics and researches related to plant defensins and their most significant uses in pathogens management in crops of economical relevance. It also intends to go deep into the study of such proteins in order to use them as a control strategy, such as production of transgenic plants and microorganisms.