Overexpression of Chalcone Isomerase (CHI) Increases Resistance Against Phytophthora sojae in Soybean

Chalcone isomerase (CHI) is a key enzyme of the flavonoid pathway that plays crucial roles in plant responses to various pathogens. Our previous study using comparative transcriptome analysis of soybean inoculated with or without Phytophthora sojae revealed Glyma.20G241500, a homolog of CHI1A in Arabidopsis thaliana, to be induced by P.sojae in soybean. In the present study, we isolated the gene from soybean cultivar Nannong 10-1, designating it GmCHI1A. GmCHI1A transcripts were detected in soybean roots, stems and leaves, with the highest levels in roots. Interestingly, GmCHI1A localizes to the cortical endoplasmic reticulum (ER). GmCHI1A was overexpressed in hairy roots to further uncover the roles of CHIs in soybean. Compared to empty vector-expressing hairy roots (EV) infected with P. sojae, hairy roots overexpressing GmCHI1A (OE) exhibited decreased P. sojae biomass accumulation, shortened the lesion lengths and reduced zoospores germination. These results demonstrate that GmCHI1A plays positive roles in the response of soybean to P. sojae.