Interação de Colletotrichum lindemuthianum com o feijoeiro e a detecção do patógeno em sementes por PCR

Abstract

Common bean is a crop of great importance to many countries and their population. However, the productivity of the crop is affected by several biotic and abiotic factors. Among the biotic factors, the anthracnose caused by Colletotrichum lindemuthianum is known to lead to considerable losses of production. The fungus has the seed as one of the major means of transmission and dissemination to short or long distances. Thus, there is a need for faster and more accurate methods in the diagnosis of seed lots. The objective of this work was to evaluate the effect of C. lindemuthianum on seeds and common bean plants, to study the transmission of fungi from seeds to plants and their detection in seed samples by molecular techniques, conventional and real time PCR (cPCR and qPCR) using specific primers. Seeds of bean cv. Pearl were inoculated for different periods (P0, P36, P72, P108 and P144 hours). Healthy seeds with different levels of fungus incidence were also used in relation to the total number of seeds. Germination, emergency speed index, initial and final stands, fresh and dry weight, incidence and electrical conductivity in two growing environments (20 and 26 °C) were evaluated to study the fungus effects on both seeds and plants. Transmission tests were evaluated in asymptomatic and symptomatic plants. For the molecular detection tests, C. lindemuthianum DNA was quantified in seed samples at different potentials and incidence levels. It was observed that the fungus has an effect on seed vigor and its quality. The variables were negatively influenced by the higher inoculum potential. Transmission rates were higher in P144 in plants growing at 20 °C. The molecular methods were effective in detecting the lowest inoculum levels in both seed and plant samples, demonstrating that these techniques can be used in routine seed laboratory analysis.