Respostas moleculares do feijão ao crestamento bacteriano comum

Abstract

The common bean (PhaseolusvulgarisL.) is one of the most produced and consumed legumes in the world. However, numerous diseases affect the cultivation of this crop, among them, the common bacterial blight caused by the bacterium Xanthomonas axonopodispv. phaseoli. Under stress conditions, the plants activate signaling cascades that increase or suppress the expression of target geneschanging the physiological responses of plants. This work aimedto analyze the common bean molecular responses tocommon bacterial blight. The experiment was carried ina randomized block design with 2 cultivars (IPR Colibri-Susceptible andIAC Milênio-Moderately Resistant) x 7 methods (seeds inoculated by immersion, seeds inoculated by vacuum infiltration, inoculated leaves, leaves only wounds, inoculated stem, only injured stem anduninoculated plants (control)) with 4replicates. Plant leaves were collectedfor DNA methylation analysis and defense gene expression by semiquantitative PCR.Disease severity was assessed at 7, 14, 21 and 28 days after sowing. At 28 days aftersowing, plants were collected for analysis of fresh and dry matter mass of leaves andstems.Another study in silicoof the regulation of the promoters of genes that acts in the signaling toattack of pathogenswas realized.The results found in subject 1 indicate that the vacuum infiltration method was the most efficient to evaluate disease severity in both bean cultivars. In addition, shoot biomass values were related to severity, ie, in plants with higher severity, shoot mass was lower. In subject 2, we were observed that the cultivar IAC Milênio had greater increase in gene expression compared to cultivar IPR Colibri, for the analyzed genes, mainly for the Phvul.002G092300gene. In addition, the promoter methylation may influencethe expression of Phvul.002G092300, Phvul.003G159700, Phvul.004G015000and Phvul.005G054300genes in the IAC Milênio and IPR Colibri in response toX. axonopodispv. phaseoli. In subject 3, we were found that among the 555 genes, 491 were expressed innodules and 486 in roots 19. In addition, 50 cis-actingregulatory elements (ERACs) were present in the promoter region of these genes and the most frequent were TATA-box,CAAT-box, MYB, MYC and AT-TATA-box. ERACs, GT1-motif, W-box and WRE3, related to biotic stress were also identified. Therefore, the results provide important data on the function of bean defencegenes in responses to common bacterial growth, representing a broad resource for the genetic improvement of this crop.