GmDBA1 and GmDBA2 Are Candidate NLR Genes Associated with Dwarfism and Enhanced Resistance to Phytophthora sojae in Soybean

Phytophthora root and stem rot (PRR), caused by Phytophthora sojae (P. sojae), severely reduces soybean yield. We isolated the recessive gmdba1 mutant from an ethyl methanesulfonate (EMS)-mutagenized population of the soybean cultivar Hedou 12 (H12). The mutant exhibited dwarfism, reduced node number, increased branching, and crinkled leaves. Genetic mapping delimited the phenotype-associated locus to an approximately 154 kb interval on chromosome 18 containing 22 annotated genes. Resequencing and targeted sequence analysis prioritized two NLR candidates, Glyma.18g226500 (GmDBA1, Dwarfism and Basal Activation 1) and Glyma.18g226800 (GmDBA2), with four reported mutant-specific SNPs (three non-synonymous substitutions). Both gmdba1 and one homozygous T2 carrying double-edited line in the two genes exhibited reduced disease symptoms following inoculation with P. sojae isolate P6497. These results support an association between perturbation of the GmDBA1/GmDBA2-containing locus, altered development, and enhanced resistance under the tested conditions. Transcriptomic and hormone analyses revealed constitutive activation of defense-related genes, jasmonic acid (JA) and salicylic acid (SA) contents in gmdba1, which likely explains the observed growth–defense tradeoff. Together, our findings characterize GmDBA1 and GmDBA2 suppresses basal resistance against P. sojae, providing a valuable genetic resource for breeding disease-resistant soybean varieties.