Genomic strategies for stacking resistance genes to Diaporthe aspalathi in soybean

MALDONADO, R; BIANCHI, J; CAMBURSANO, M.V.; MORANDI, E.N.; CHIESA, M.A.

Santa Fe

Congreso; XXXIII Argentinian meeting of Plant Physiology (Reunión Argentina de Fisiología Vegetal); 2021

Among the soybean [Glycine max (L.) Merr.] diseases that affect this crop, stem canker is of great importance. Diaporthe aspalathi is one of the causal agents and resistance to this pathogen has been documented, with five loci (Rdm1 through Rdm5) conferring major resistance. The use of resistant varieties is the most effective and environmentally friendly strategy to reduce losses caused by biotic stresses. Once a resistance source is available, the analysis of the genetic control and mapping of the genomic regions associated with the resistance provide essential information. First, molecular markers (MM) can be used in breeding programs for the introgression and stacking of these loci in elite germplasm. Besides, fine mapping allows the identification of candidate genes responsible for the resistance. Thus, the objectives of this work are to map the Rdm3 gene and identify MM tightly link, and then stack Rdm3 with Rdm4-5 loci, previously mapped by our group, in order to have an extensive and more durable resistance. Hence, a biparental population (160 F2:3 families) from a cross between RA702 (susceptible) and Crockett (resistant) has been pheno- and genotypically analyzed by progeny tests with two different local isolates of the pathogen. The results fitted well with the expected segregation of a simple inherited and completely dominant gene. Furthermore, after a systematic search, polymorphic Single Simple Repeats (SSR)-MM were identified in each molecular linkage group of the soybean genetic map, which will be used in bulked segregant analysis for the identification of the genomic region associated with Rdm3.