Inheritance and genetic mapping of resistance to Asian soybean rust in cultivar TMG 803

This study analyzed the inheritance and identified microsatellite markers linked to the resistance gene to Phakopsora pachyrhizi in soybean cultivar TMG 803. Hybridization between the cultivars TMG 803 and BRS Valiosa RR was performed to obtain F1 progenies and the F2 population. The response of the parents ‘TMG 803’ and ‘BRS Valiosa RR’ to P. pachyrhizi was, respectively, resistant and susceptible, and among the 116 F2 plants, 93 were resistant and 23 susceptible, under natural infection and field conditions. It was found that the resistance of cultivar TMG 803 is controlled by one gene with complete dominance, mapped as resistance locus Rpp4 of linkage group G. Of the 16 tested, one microsatellite marker, sc21_3420, was completely linked to the resistance gene (distance 0.0cM) and the favorable allelic form was present in cultivar TMG 803, which may therefore be useful in assisted selection in segregating populations

Comparative RNA-Seq Analysis Uncovers a Complex Regulatory Network for Soybean Cyst Nematode Resistance in Wild Soybean (Glycine soja)

Abstract Soybean cyst nematode (SCN) is the most damaging pest of soybean worldwide. The molecular mechanism of SCN resistance remains largely unknown. We conducted a global RNA-seq comparison between a resistant genotype (S54) and a susceptible genotype (S67) of Glycine soja, the wild progenitor of soybean, to understand its regulatory network in SCN defense. The number of differentially expressed genes (DEGs) in S54 (2,290) was much larger than that in S67 (555). A number of defense-related genes/pathways were significantly induced only in S54, while photosynthesis and several metabolic pathways were affected in both genotypes with SCN infection. These defense-associated DEGs were involved in pathogen recognition, calcium/calmodulin-mediated defense signaling, jasmonic acid (JA)/ethylene (ET) and sialic acid (SA)-involved signaling, the MAPK signaling cascade, and WRKY-involved transcriptional regulation. Our results revealed a comprehensive regulatory network involved in SCN resistance and provided insights into the complex molecular mechanisms of SCN resistance in wild soybean