Genetic diversity of the germplasm active bank of Capsicum of UNEMAT based on components resistant to the fungus Colletotrichum gloeosporioides

Abstract

Peppers and chilies belong to the Solanaceae family and to the genus Capsicum. The production of this vegetable is increasing in Brazil. However, there are several phytosanitary problems that are causing heavy losses to the culture, among them anthracnose. The objective of this study was to evaluate the genetic diversity of the Capsicum Germplasm Active Bank (GAB) of the UNEMAT based on components resistant to the fungus Colletotrichum gloeosporioides. 88 accessions of Capsicum spp., belonging to the Germplasm Active Bank of UNEMAT, were evaluated for reaction to the fungus Colletotrichum gloeosporioides. The experimental design was completely randomized blocks with three replications, being four unripe fruits and four ripe fruits per repetition. Both ripe and unripe fruits were collected from each plot, taken to the laboratory, disinfected and packaged in Styrofoam trays covered with a transparent plastic bag; inside each tray, moistened pieces of filter paper were placed to build the humid chamber. The trays were in an environment with a temperature controlled at 24°C ± 2. The evaluation of all the fruits was performed daily based on the measurement of lesion diameter and length of each fruit with an interval of 24 hours between each evaluation for 11 days. The assessment data were subjected to multivariate analysis and to the UPGMA clustering method. There is genetic variability in the GAB of UNEMAT with the formation of different accession groups based on resistance to anthracnose for both clustering methods applied, i.e., UPGMA and Modified Tocher. There was the formation of four groups in the dendrogram, especially regarding the accession 81 (C. annuum), which had the highest genetic dissimilarity in relation to other accessions, standing isolated in one group. According to the 3D dispersion graph, there was the formation of three groups with genetic dissimilarity among them. According to the modified Tocher method, there was the formation of five groups; the accession 38 (C. chinense) was grouped separately from the other accessions in the group five. The resistance components that had a higher relative contribution to estimate the genetic variability among analyzed accessions were area under the disease progress curve (AUDPC), lesion diameter and length on the seventh day of evaluation (DL7), and incubation period (IP), but it is necessary to use at least seven variables and explain 80% of the variability of the experiment.