Discovery and Analysis of a Quantitative Trait Locus Associated with Resistance to Meloidogyne incognita in Glycine latifolia, a Wild Perennial Relative of Soybean.

Perennial Glycine species are potentially valuable genetic resources that can be used to improve disease resistance in soybean by gene transfer techniques. From a previous screening of perennial Glycine species, we found that G. latifolia plant introduction (PI) 559300 showed a high level of resistance to the southern root-knot nematode (Meloidogyne incognita). Here, we identified a quantitative trait locus (QTL) associated with resistance to M. incognita in G. latifolia by phenotyping recombinant inbred lines (RILs) derived from resistant (PI 559300) and susceptible (PI 559298) G. latifolia accessions and single-nucleotide polymorphism (SNP) markers generated through genotyping by sequencing. The analysis identified a single locus of 1.66 Mb associated with M. incognita resistance on G. latifolia chromosome (Chr) 13 that explained 33.3% of the phenotypic variance. This region contains 114 putative genes, including 16 leucine-rich repeat containing genes and 7 defense-related genes. F₁ hybrids generated from crosses between parental lines showed a comparable resistance level to the resistant parents, suggesting that the identified locus is dominantly inherited. To validate the identified QTL, we developed high-resolution melting (HRM) markers linked to a SNP within this locus. HRM genotyping successfully distinguished homozygous and heterozygous alleles and predicted RIL phenotypes with approximately 80% accuracy. Interestingly, the QTL is syntenic with a locus on G. max Chr13 previously found associated with resistance to root-knot nematodes and other non-nematode pathogens. In summary, the newly discovered locus in the wild perennial G. latifolia has the potential for enhancing M. incognita resistance in soybean.