Validação de marcador molecular associado à resistência do feijoeiro comum a raça 65 de Colletotrichum Lindemuthianum

Abstract

The genetic control of anthracnose, caused by Colletotrichum lindemuthianum fungus, has become a challenge due the great pathogenic variability among and within races. However, SNPs markers linked to resistance loci to different C. lindemuthianum isolates have been identified and have potential to be used in common bean breeding programs (Phaseolus vulgaris L.). In this context, the present study aimed to validate the SNP marker ss715649771 association with resistance to the isolate LV134 of race 65. For this, phenotypic and genotypic evaluations were carried out in an F2 population of 192 plants, derived from the cultivars BRS Cometa (susceptible) and BRSMG Ouro Vermelho (resistant) cross, and also in a 55 genotypes panel of cultivars and elite lines from different breeding programs. In addition, a linear regression analysis of the marker effect was carried out, and the selection efficiency (SE) for codominant markers was estimated. The generation F2 phenotyping resulted, as expected, in the 3R:1S ratio (p = 0.093), and the genotyping also adjusted to 1CC:2CT:1TT (p = 0.095). The recombination frequency of the F2 population was estimated at 10.0%, with 11 plants presenting recombinant phenotypes (4 resistant with T allele, and 7 susceptible with C allele). The estimated SE was 96%, and the linear regression model was statistically significant, explaining about 42% of the variation. The panel analyses of 55 genotypes revealed 41% of recombinant individuals (9 resistant with T allele, and 14 susceptible with C allele). Considering the high SE value, results shows a high potential use of this marker in Marker-Assisted Selection routines. However, the 10cM distance between the marker and the gene, and the number of recombinant individuals observed on the cultivars panel can suggest the existence of other alleles that confer resistance to race 65 in the evaluated cultivars. The use of the SNPss715649771 marker in breeding programs, together with other already known markers, will contribute to the pyramiding of resistance genes to this race in common bean lines.