Genome-wide identification of chalcone reductase gene family in soybean: Insight into root-specific GmCHRs and phytophthora sojae resistance

Soybean is one of the main grain legumes worldwide. Soybean farmers lose billions of dollars’ worth of yield annually due to root and stem rot disease caused by the oomycete Phytophthora sojae. Many strategies have been developed to combat the disease however these methods have proven ineffective in the long term. A more cost effective and durable approach is to select a trait naturally found in soybean that can increase resistance to infection by P. sojaie. Compared to single gene or complete resistance, partial resistance is durable and places less selection pressure on the pathogen. Partial resistance is conferred by several minor genes. Phytoalexin glyceollins have been correlated with strong partial resistance in soybean. Glyceollins are isoflavonoids that play a role as a plant's basal and innate response to biotic and abiotic stress. The first key enzyme (legume-specific) exclusively involved in glyceollin synthesis is chalcone reductase (CHR). Very little is known about the importance of CHR, which directs flow toward the production of glyceollins in soybean. Here we report the genome-wide identification of CHRs in soybean and demonstrate that the root-specific CHRs are induced upon pathogen infection, and are located near QTLs and QTL markers linked to P. sojae resistance. This information may be used eventually in breeding programs as a gene stacking approach for improving resistance to P. sojae in soybean.