RESUMO
Anthracnose is a disease caused by Colletotrichum spp., one of the world's most damaging sweet and chili pepper pathogens, especially in tropical and subtropical regions. In the state of Rio de Janeiro, anthracnose is one of the main obstacles for pepper crops. However, to date no research has focused on the identification and characterization of the pathogen, which is fundamental to understand the scope of the disease in the state. Thus, the correct identification of the fungal species and pathogenicity studies can provide important support for disease management and control, apart from identifying possible resistance sources for exploitation in peppers breeding programs. In this study, 11 Colletotrichum isolates were collected from peppers with typical symptoms in the Rio de Janeiro state. These isolates were characterized based on morpho-cultural characteristics and sequencing data from five regions (ITS, ACT, CAL, ß-TUB and GAPDH), and the genetic variability was estimated by AFLP markers. Simultaneously, microscopy images of the colonization by the fungal species on unripe Capsicum annuum fruits were taken. Pathogenicity was tested and resistance sources were sought by means of infection of ripe and unripe fruits of 50 Capsicum baccatum accessions. The resulting data showed that all isolates belong to Colletotrichum scovillei specie. About the pathogenicity of Capsicum baccatum, differentiated, stage-specific responses, with higher resistance of ripe fruits were recorded. In addition, four possible sources of Colletotrichum scovillei resistance were detected among the tested accessions. The combination of these data can contribute to future studies on the interaction of Colletotrichum scovillei-Capsicum spp., a research line that is still unexploited in the main areas of this anthracnose fungus.
RESUMO
BACKGROUND: Plant genomes are rich in repetitive sequences, and transposable elements (TEs) are the most accumulated of them. This mobile fraction can be distinguished as Class I (retrotransposons) and Class II (transposons). Retrotransposons that are transposed using an intermediate RNA and that accumulate in a "copy-and-paste" manner were screened in three genomes of peppers (Solanaceae). The present study aimed to understand the genome relationships among Capsicum annuum, C. chinense, and C. baccatum, based on a comparative analysis of the function, diversity and chromosome distribution of TE lineages in the Capsicum karyotypes. Due to the great commercial importance of pepper in natura, as a spice or as an ornamental plant, these genomes have been widely sequenced, and all of the assemblies are available in the SolGenomics group. These sequences were used to compare all repetitive fractions from a cytogenomic point of view. RESULTS: The qualification and quantification of LTR-retrotransposons (LTR-RT) families were contrasted with molecular cytogenetic data, and the results showed a strong genome similarity between C. annuum and C. chinense as compared to C. baccatum. The Gypsy superfamily is more abundant than Copia, especially for Tekay/Del lineage members, including a high representation in C. annuum and C. chinense. On the other hand, C. baccatum accumulates more Athila/Tat sequences. The FISH results showed retrotransposons differentially scattered along chromosomes, except for CRM lineage sequences, which mainly have a proximal accumulation associated with heterochromatin bands. CONCLUSIONS: The results confirm a close genomic relationship between C. annuum and C. chinense in comparison to C. baccatum. Centromeric GC-rich bands may be associated with the accumulation regions of CRM elements, whereas terminal and subterminal AT- and GC-rich bands do not correspond to the accumulation of the retrotransposons in the three Capsicum species tested.
Assuntos
Capsicum/classificação , Capsicum/genética , Variação Genética , Genoma de Planta , Sequências Repetidas Terminais , Cromossomos de Plantas/genética , Genômica , Filogenia , Sequências Repetitivas de Ácido Nucleico , RetroelementosRESUMO
This study evaluated the transcriptional profile of genes related to nitrogen (N) assimilation in coffee plants susceptible and resistant to rust fungi under N sufficiency and N suppression. For this purpose, we inoculated young coffee leaves with Hemileia vastatrix uredospores and collected them at 0, 12, 24 and 48 hours post-inoculation (HPI) to evaluate the relative expressions of genes encoding cytosolic glutamine synthetase (CaGS1 ), plastid glutamine synthetase (CaGS2 ), nitrate reductase (CaNR), and asparagine synthetase (CaAS). The genes exhibited distinct patterns of transcriptional modulation for the different genotypes and N nutritional regimes. The resistant genotype (I59) presented high levels of transcription in response to pathogen inoculation for CaNR and CaGS1 genes, evaluated under N sufficiency in the initial moments of infection (12 HPI). The gene CaGS1 also showed a peak at 48 HPI. The susceptible genotype (CV99) showed increased transcript rates of CaNR at 12 and 24 HPI in response to rust inoculation. The transcriptional patterns observed for CV99, under N suppression, were high levels for CaAS and CaGS2 at all post-inoculation times in response to coffee leaf rust disease. In addition, CaGS1 was up-regulated at 48 HPI for CV99. Cultivar I59 showed high transcript levels at 12 HPI for CaAS and peaks at 24 and 48 HPI for CaGS2 in inoculated samples. Consequently, total chlorophyl concentration was influenced by N suppression and by rust infection. Regarding enzyme activities in vitro for glutamine synthetase and CaNR, there was an increase in infected coffee leaves (I59) and under N sufficiency. Moreover, CV99 was modulated in both N nutritional regimes for GS activity in response to rust. Our results indicate that N transport genes trigger a differential modulation between genotypes through the action of rust disease.
RESUMO
Estimating the genetic variability in germplasm collections is important not only for conserving genetic resources, but also for plant breeding purposes. However, generating a large number of different categories data (qualitative and quantitative) often complicate the analysis and results interpretation, resulting in an incomplete distinction of accessions. This study reports the characterization and evaluation of 14 pumpkin (Cucurbita moschata) accessions collected from farms in the northern region of Rio de Janeiro state. Genetic diversity among accessions was also estimated using qualitative and quantitative variables considering joint analysis. The plants were grown under field conditions in a randomized block design with three replications and six plants per plot. Eight qualitative traits (leaf size; seed shape; seed color; color of the fruit pulp; hollow; fruit shape; skin color, and fruit skin texture) and eight quantitative traits (fruit weight; fruit length; fruit diameter; soluble solids, 100 seed weight, and wall thickness measured in the middle and in the lower stem) were evaluated. The data were analyzed considering the Gower distance, and cluster analysis was performed using unweighted pair group method with arithmetic mean (UPGMA). Variability among accessions was observed considering morphoagronomic data. The Gower distance together with UPGMA cluster allowed for good discrimination between accessions in the groups, demonstrating that the simultaneous analysis of qualitative and quantitative data is feasible and may increase the understanding of the variation among accessions.(AU)
A estimativa da variabilidade genética em banco de germoplasma é importante não só para conservação dos recursos genéticos, mas também para sua utilização no melhoramento de plantas. Entretanto, a geração de um grande número de variáveis de diferentes categorias (qualitativas e quantitativas) pode dificultar a análise e a interpretação dos resultados, muitas vezes resultando na incompleta distinção dos acessos. Este trabalho objetivou caracterizar 14 acessos de Cucurbita moschata coletados no Norte do Estado do Rio de Janeiro e estimar a divergência genotípica entre esses acessos, utilizando a análise conjunta de variáveis qualitativas e quantitativas. As plantas foram cultivadas a campo, no delineamento de blocos ao acaso, com três repetições e seis plantas por parcela. Foram avaliadas oito variáveis qualitativas (tamanho da folha; formato da semente; cor da semente; cor da polpa do fruto; reentrância; formato do fruto; cor predominante da casca e textura da superfície da casca) e oito variáveis quantitativas (massa do fruto; comprimento e diâmetro do fruto; teor de sólidos solúveis totais; massa de 100 sementes, e espessura da polpa no pedúnculo, mediana e inferior). Os dados foram analisados considerando a distância de Gower e o agrupamento dos acessos foi realizado pelo método UPGMA. Verificou-se variabilidade entre os acessos coletados e a distância de Gower, juntamente com agrupamento UPGMA, permitiu a discriminação dos acessos nos grupos, demonstrando que análise simultânea de variáveis é viável e permite maior eficiência no conhecimento da variabilidade entre os acessos avaliados.(AU)
Assuntos
Banco de Sementes , Cucurbita/genética , Variação Genética , Patrimônio GenéticoRESUMO
Estimating the genetic variability in germplasm collections is important not only for conserving genetic resources, but also for plant breeding purposes. However, generating a large number of different categories data (qualitative and quantitative) often complicate the analysis and results interpretation, resulting in an incomplete distinction of accessions. This study reports the characterization and evaluation of 14 pumpkin (Cucurbita moschata) accessions collected from farms in the northern region of Rio de Janeiro state. Genetic diversity among accessions was also estimated using qualitative and quantitative variables considering joint analysis. The plants were grown under field conditions in a randomized block design with three replications and six plants per plot. Eight qualitative traits (leaf size; seed shape; seed color; color of the fruit pulp; hollow; fruit shape; skin color, and fruit skin texture) and eight quantitative traits (fruit weight; fruit length; fruit diameter; soluble solids, 100 seed weight, and wall thickness measured in the middle and in the lower stem) were evaluated. The data were analyzed considering the Gower distance, and cluster analysis was performed using unweighted pair group method with arithmetic mean (UPGMA). Variability among accessions was observed considering morphoagronomic data. The Gower distance together with UPGMA cluster allowed for good discrimination between accessions in the groups, demonstrating that the simultaneous analysis of qualitative and quantitative data is feasible and may increase the understanding of the variation among accessions.
A estimativa da variabilidade genética em banco de germoplasma é importante não só para conservação dos recursos genéticos, mas também para sua utilização no melhoramento de plantas. Entretanto, a geração de um grande número de variáveis de diferentes categorias (qualitativas e quantitativas) pode dificultar a análise e a interpretação dos resultados, muitas vezes resultando na incompleta distinção dos acessos. Este trabalho objetivou caracterizar 14 acessos de Cucurbita moschata coletados no Norte do Estado do Rio de Janeiro e estimar a divergência genotípica entre esses acessos, utilizando a análise conjunta de variáveis qualitativas e quantitativas. As plantas foram cultivadas a campo, no delineamento de blocos ao acaso, com três repetições e seis plantas por parcela. Foram avaliadas oito variáveis qualitativas (tamanho da folha; formato da semente; cor da semente; cor da polpa do fruto; reentrância; formato do fruto; cor predominante da casca e textura da superfície da casca) e oito variáveis quantitativas (massa do fruto; comprimento e diâmetro do fruto; teor de sólidos solúveis totais; massa de 100 sementes, e espessura da polpa no pedúnculo, mediana e inferior). Os dados foram analisados considerando a distância de Gower e o agrupamento dos acessos foi realizado pelo método UPGMA. Verificou-se variabilidade entre os acessos coletados e a distância de Gower, juntamente com agrupamento UPGMA, permitiu a discriminação dos acessos nos grupos, demonstrando que análise simultânea de variáveis é viável e permite maior eficiência no conhecimento da variabilidade entre os acessos avaliados.