RESUMO

Post-harvest diseases like fruit crown rot (CR) on bananas (Musa spp.) worldwide are mainly attributed to Colletotrichum gloeosporioides (Berk. & Curt.) von Arx and Lasiodiplodia theobromae (Pat.) Griff. & Maubl (Sangeetha et al., 2012; Riera et al., 2019). In April 2019, at a banana farm (cultivar Williams) located in El Oro province (location at 79° 54' 05" W; 03° 17' 16" S), thirty hands were randomly collected from the postharvest process and further placed in a humid chamber at 20 ºC until signs of the disease progressed and became more evident (from 3 days to 20 days). Ten hands presented initial symptoms related to CR during the postharvest process, which included crown or peduncle rot with mycelial development on the crown's surface, leading to the blackening of tissues at the site of the wound left when the cluster was cut. Crown fruit fragments (~0.5 cm) from the edge of healthy tissue and diseased tissue underwent a series of disinfection steps, initially in ethanol (70%) for 1 min, followed by sodium hypochlorite (1%) for 1 min, rinsed three times with sterile distilled water, and dried on sterile filter paper for 10 min. The fragments were placed onto Potato dextrose agar (PDA) + chloramphenicol (100 mg L-1) and incubated at 25°C in darkness for five days. Five isolates with different colony morphologies were obtained. An initial screen of the pathogenicity of all isolates showed that only one isolate showed disease activity in banana crowns. This isolate, C1, showed grayish-white aerial mycelium in culture as described above and, after ten days, became black. We did a full pathogenicity test with C1 using ten individual banana fruits (cv. Williams Cavendish). Briefly, one disc (Ø of 5 mm) of the fungus with agar was placed on the acropetal part of the banana fruit (on the peel) and another piece in the crown without wounding. Inoculated fruit were in a humid chamber at 20 °C for 20 days. Uninoculated fruits constituted the control. Isolate C1 caused 100% of the fruit and crowns to rot, with symptoms similar to those initially observed from fruit collected at the postharvest process (Fig. S1d). The fungus was re-isolated from symptomatic tissue, and its identity was confirmed through morphological characteristics consistent with Lasiodiplodia sp. Matured conidia of all mono hyphal strains (Fig. S1b) appeared dark brown with a single septum, having an ovate shape, and displayed longitudinal striations along their thickened walls (Fig. S1c). The dimensions of the mature conidia ranged from 16.02 - 26.85 x 11.09 - 16.74 µm (n = 60). Morphological characteristics showed similarity to Lasiodiplodia sp. (Alves et al., 2008). Microscopic observations were further confirmed by sequencing three loci: the internal transcribed spacer (ITS), ß-tubulin, and partial translation elongation factor-1α (TEF-1α). Fungal genomic DNA from the C1 isolate was PCR amplified using ITS5/ITS4, EF1-728F/986R, and Bt2A/Bt2B primers, respectively, according to Glass & Donaldson (1995) and Bautista-Cruz et al. (2019). The resulting amplicons were sequenced, and those sequences were deposited in GenBank with the accession numbers ITS: PP532861, TEF-1α: PP551938, and ß-tubulin: PP537587. Sequence alignment was conducted using ClustalW under the MEGA 11.0 software package (Tamura et al., 2021). Subsequently, phylogenetic analysis was performed using Bayesian inference using the BEAST v1.8.4 program (Drummond & Rambaut, 2007). The concatenated sequence of the isolate revealed clustering to the Lasiodiplodia theobromae clade, confirming its identity. To our knowledge, this is the first report of this pathogen causing CR on banana fruit in Ecuador. Based on the report of CR in the country, banana exporters and the Ecuadorian government should consider developing disease management methods that include the cultivation, shipping, ripening, and storage processes of the fruit.

RESUMO

Abstract The genus Capsicum, native to tropical and subtropical America, belongs to the Solanaceae family, which includes commercially important vegetables such as chilies and green peppers. The silverleaf whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes losses to vegetables including Capsicum species. Among the alternatives of pest control, an effective, economical, and environmentally compatible method is the resistance of the host plant. Infestation by B. tabaci was evaluated in 73 Capsicum genotypes, corresponding to the species C. annuum, C. baccatum, C. sinense, C. frutescens and C. pubescens from an Ecuadorian genebank. Eighty-four percent of the C. baccatum genotypes evaluated showed the highest population densities of B. tabaci, while all the genotypes of C. sinense and C. frutescens had the lowest values (p < 0.05). The non-preference of adults and the scarce oviposition of B. tabaci on genotypes of C. sinense and C. frutescens suggests resistance due to antixenosis. These results could guide breeding programs for the resistance of Capsicum species to B. tabaci infestations.

Resumen El género Capsicum es nativo de América tropical y subtropical, pertenece a la familia Solanaceae e incluye ajíes y pimientos, que son hortalizas comercialmente importantes. La mosca blanca Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) ocasiona pérdidas en hortalizas incluyendo especies de Capsicum. Entre las alternativas de control de plagas, un método eficaz, económico y ambientemente compatible es la resistencia de la planta hospedera. Se evaluó la infestación por B. tabaci en 73 genotipos de Capsicum nativos de Ecuador, correspondientes a las especies C. annuum, C. baccatum, C. chinense, C. frutescens y C. pubescens, provenientes de un banco de germoplasma ecuatoriano. El 84% de los genotipos de C. baccatum evaluados mostraron las mayores densidades poblacionales de B. tabaci, mientras que los menores valores los tuvieron todos los genotipos de C. sinense y C. frutescens (p < 0.05). La no preferencia de adultos y la escasa oviposición de B. tabaci sobre genotipos de C. sinense y C. frutescens sugiere resistencia por antixenosis. Estos resultados podrían orientar programas de mejoramiento genético para la resistencia de especies de Capsicum ante infestaciones por B. tabaci.

RESUMO

Interaction among nitrogen fertilization using bovine manure, poultry manure, Jatropha curcas seed cake and urea, and the diseases Ramularia leaf spot (RLS) and Boll rot (BR), caused by Ramulariopsis pseudoglycines and Diplodia gossypina, respectively, in cotton plants (Gossypium hirsutum L.), was studied under field conditions. Intensity (incidence and severity in percentage) of RLS and incidence (%) of BR were evaluated over time, starting in reproductive stage B1 (first visible flower bud). A randomized complete block design with a 4x4 factorial arrangement was used (fertilizers x doses), totaling 16 treatments with four replications. Disease progress was analyzed with the nonlinear Logistic and Gompertz models, obtaining the epidemiological parameters amount of initial disease (Y0) and progress rate (r). Plants fertilized with 50 kg N ha-1, presented an incidence twice greater than those obtained with other fertilizers. The Logistic model better fits RLS, but no model could represent BR. Only the epidemiological parameters of RLS were affected differently in this experiment compared to BR disease. The possible role of organic and inorganic nitrogen fertilization in the RLS and BR management is discussed.

Assuntos

RESUMO

Genetic resistance is the main strategy to control Fusarium wilt in common bean. Despite this, few studies have focused on defense mechanisms involved in bean resistance to Fusarium oxysporum f. sp. phaseoli (Fop). Thus, the present study aimed to investigate the changes in xylem morphology and involvement of phenylpropanoid compounds and their biosynthetic enzymes in bean resistance against Fop. Uirapuru and UFSC-01 genotypes characterized, respectively, as susceptible and resistant were used. In roots and hypocotyls, guaiacol peroxidase (GPX), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) activities were determined at 0, 1, 2, 3, 4, 5, and 6 days after inoculation (dai), and flavonoids, total phenolics, and lignin content were quantified at 0, 3, and 6 dai. Cross sections of taproots and hypocotyls were examined under epifluorescence (at 1, 3, and 6 dai) and transmission electron (at 6 dai) microscopic to analyze the morphology of xylem cell walls. Overall, there was an increase in the activity of all studied enzymes in resistant bean plants, mainly during advanced colonization stages. Modifications in xylem morphology were more intense in roots of resistant genotype resulting in an increase of occluded cells, organelles, and cell wall strengthening. This study provides evidence that bean resistance is associated with increased phenylpropanoid enzymatic activity and cell wall reinforcement of some xylem cells.

Assuntos

RESUMO

O objetivo desse trabalho foi quantificar a intensidade de doenças, o rendimento de grãos e seus componentes em genótipos promissores de feijão durante a safra agrícola de verão em Quevedo, Equador. Os materiais genéticos utilizados foram as linhas Cf4 0-0-2-1, Cf6 0-0-4-9 e Cf6-0-0-4-8 (hábito de crescimento determinado tipo Ia), SER-03 e SER-08 (hábito de crescimento indeterminado tipo IIb), e duas variedades estrangeiras FTS Soberano e BRS Valente (hábito de crescimento indeterminado, grupo preto) utilizadas como testemunhas. Foi quantificada a intensidade da ferrugem (Uromyces appendiculatus Pers.:Pers.) durante quatro semanas (09/09, 16/09, 23/09 e 30/09) e mela [Rhizoctonia solani (Kuhn)] durante seis semanas (26/08, 02/09, 09/09, 16/09, 23/09 e 30/09) em folíolos centrais destacados, sendo esses valores obtidos integralizados na área abaixo da curva de progresso da doença (AACPD). Para o caso da mela, foi quantificado também o número de lesões folíolo-1 durante os estádios reprodutivos R7 e R8. Após a colheita foi avaliada a incidência das podridões cinzenta [Macrophomina phaseolina (Tassi) Goid.] e parda (R. solani), e quantificados os componentes de produção por planta (número de nós, número de vagens, número de grãos, número de grãos por vagem e número de vagens estéreis) e rendimento (kg ha-1). O delineamento experimental foi o de blocos completos ao acaso com 7 tratamentos e 4 repetições. Para a comparação entre as médias dos tratamentos empregou-se o teste de Scott-Knott a 5% de probabilidade do erro. Destacou-se a variedade FTS Soberano por acumular uma menor AACPS da ferrugem. Com relação a mela, as linhas promissoras SER-03 e SER-08, e as variedades FTS Soberano e BRS Valente mostraram menor quantidade de doença em todas as variáveis analisadas. Para as doenças radiculares, as linhas Cf6 0-0-4-8 e SER-03 obtiveram menor incidência de podridão parda, entretanto esses mesmos materiais incluindo o SER- 08 evidenciaram superioridade sanitária para podridão cinzenta. A linha promissora SER-03 e as variedades FTS Soberano e BRS Valente mostraram médias superiores no número de nós por planta, número de vagens por planta, número de grãos por planta e número de grãos por vagem por planta. Finalmente, as linhas SER-08, Cf6 0-0-4-9 e SER-08 e a variedade BRS Valente obtiveram o maior rendimento de grãos (kg ha-1).

The objective of this study was to quantify the intensity of disease, yield and its components in bean genotypes promising during the summer season in Quevedo, Ecuador. The genetic material used were the lines Cf4 0-0-2-1, Cf6 0-0-4-9 and Cf6 0-0-4-8 (habit growth determinate type Ia), SER-03 and SER-08 (growth habit indeterminate type IIb), and two foreign varieties FTS Soberano and BRS Valente (black group with habit growth indeterminate) used as controls. The intensity of rust (Uromyces appendiculatus Pers.: Pers.) and web blight [Rhizoctonia solani (Kuhn)] were quantified in central leaflets during four weeks (09/09, 16/09, 23/09 and 30/09) for the first disease and six weeks (26/08, 02/09, 09/09, 16/09, 23/09 and 30/09) for the second, these values being paid-in the area under the disease progress curve (AUDPC). For the case of web blight was also quantified the number of lesions leaflet-1 during reproductive stages R7 and R8. Similarly, after the harvest was determined the incidence of gray rot [Macrophomina phaseolina (Tassi) Goid.] and brown (R. solani), and quantified the yield components per plant (number of nodes, number of pods, number of grains, number of grains per pod and sterile pods) and yield (kg ha-1). The experimental design was a randomized complete block design with seven treatments and four replications. To compare the treatment means was employed the test Scott-Knott at 5% probability of error. Highlighted the variety FTS Soberano for accumulate a lower AUDPCS rust. Regarding the web blight, the promising lines SER-03 and SER-08, and the varieties FTS Soberano and BRS Valente showed less disease in all variables. For root diseases, the lines Cf6 0-0-4-8 and SER-03 had a lower incidence of brown rot, however these same materials including the SER-08 showed superiority sanitary of gray rot. The promising line SER-03 and the varieties FTS Soberano and BRS Valente showed higher average number of nodes per plant, number of pods per plant, number of grains per plant and number of grains per pod per plant. Finally, the lines SER-08, Cf6 0-0-4-9 and the varieties SER-08 and BRS Valente showed a highest grain yield (kg ha-1).

Assuntos

RESUMO

El objetivo del estudio fue evaluar las características agronómicas, productivas y calidad de grano de las variedades de soya P-34 y KAMERUN introducidas de Colombia, en comparación con tres variedades nacionales, durante las épocas lluviosa y seca, en Quevedo, Los Ríos, Ecuador. Fueron evaluadas variables agronómicas (días a floración, acame de plantas, altura de planta y de carga), productivas (número de ramas por planta, de nudos por planta, de vainas por planta, de granos por vaina, de granos por planta y de semillas en 100 gramos, peso de 100 granos y de grano por parcela, así como rendimiento de grano por hectárea) y calidad de grano (rajadura en el tegumento, moteado, mancha púrpura e incidencia fúngica). El diseño experimental utilizado en este trabajo fue el de Bloques Completos al Azar (DBCA), con cinco tratamientos y cuatro repeticiones. Todas las variables fueron sometidas al análisis de variancia. Se empleó la prueba de Tukey (p>0,05) entre las medias de los tratamientos para cada época de forma independiente, mientras que para las medias obtenidas entre las épocas lluviosa y seca, se empleó la prueba t-Student. Según las condiciones en que se condujo este experimento, se constató la influencia de la época de siembra en la mayoría de variables evaluadas, mientras que el material genético promisorio, fue la variedad P-34, por mostrar características agronómicas, productivas y calidad de grano superiores a las demás, pudiendo ser recomendada para la siembra.

This work aimed to evaluate the agronomic, production and grain quality of soybean varieties KAMERUN and P-34 introduced from Colombia, compared with three national varieties during the rainy and dry season, in Quevedo, Los Ríos, Ecuador. Agronomic variables were evaluated (days to flowering, plants overturned, height plant and first pod), productive (number of branches per plant, nodes per plant, pods per plant, seeds per pod, grains per plant and seeds in 100 grams, weight of 100 seeds, grain per plot and grain yield per hectare) and grain quality (broken seed in the integument, seed mottling, purple stain and fungal incidence). The experimental design used in this study was the Complete Randomized Bloc design with five treatments and four replications. All variables were subjected to analysis of variance. Multiple range Turkey's test (p<0,05) was used, between treatment means for each season independently; while for the means obtained between the rainy and dry seasons, t-Student test was used. Under our conditions, most of the evaluated variables were affected by the planting season. The variety P-34 was considered a promising material for showing agronomic characteristics, grain production and quality superior to others and may be recommended for planting.

Assuntos

RESUMO

Se condujo una investigación en el Trópico Húmedo Ecuatoriano (THE), dirigida a encontrar un método eficiente para evaluar la resistencia genética en árboles de Schizolobium parahybum (pachaco) frente al complejo Ceratocystis: C. paradoxa, C. moniliformis, y C. fimbriata. Se estudiaron dos métodos basados en el empleo de dos tipos de tejidos vegetales: a) tejidos de ramas laterales, y 2) tejidos de corteza fustal. Se emplearon cinco rodales de pachaco, tres de los cuales son considerados de introducción original de la especie forestal al THE desde la amazonía, y dos que son descendientes de los primeros. Los resultados permitieron definir que el método basado en tejidos de corteza fustal, fue el más eficiente y logísticamente viable. La metodología final aplicada, consistió en extraer corteza desde árboles adultos, reducirla a secciones pequeñas de 1,5 cm x 4 cm (6 cm2) y mantenerlas en una cámara húmeda durante 96 horas. Una vez distribuidas las secciones de corteza, se inocularon con 0,45mL-1 de una suspensión calibrada a razón de 30.000 unidades de infección (ascosporas, conidias y micelio). Para la evaluación, se empleó una escala arbitraria de 0 a 4 que permitió estimar el crecimiento de micelio y número de peritecios para cada uno de los hongos. Esta metodología permitió discriminar entre árboles: resistentes (0,0 a 1,0), moderadamente resistentes (1,1 a 2,0), susceptibles (2,1 a 3,0), y muy susceptibles (3,1 a 4,0), lo cual la hace viable para futuros trabajos de selección de individuos y mejoramiento genético de la especie.

A research was conducted in the Humid Tropics of Ecuador (THE), aimed at finding an efficient method to evaluate genetic resistance in Schizolobium parahybum (Pachaco) trees against Ceratocystis complex: C. paradoxa, C. moniliformis and C. fimbriata. We studied two methods based on the use of two types of plant tissues: a) tissue of lateral branches, and 2) stem bark tissues. Five forest of pachaco were used, three of which are considered original introduction of forestry specie to THE from the Amazon, and two who are descendants of the former. The results allowed to define the method based on stem bark tissue was the most efficient and logistically feasible. The final methodology applied, consisted in to remove bark from mature trees, reducing it to small sections of 1.5 cm x 4 cm (6cm2) and maintained in a moist chamber for 96 hours. Once distributed the sections of bark, were inoculated with 0.45mL-1 of a suspension calibrated at a rate of 30.000 units of infection (ascospores, conidia and mycelium). For evaluation, we used an arbitrary scale from 0 to 4, which allowed to estimate the growth of mycelium and perithecia number for each of the fungi. This methodology allows us to discriminate between trees: resistant (0.0 to 1.0), moderately resistant (1.1 to 2.0), susceptible (2.1 to 3.0), and very susceptible (3.1 to 4 , 0), which makes it viable for future selection of individuals and breeding of the forest species.

Assuntos