Overexpression of gma-miR1510a/b suppresses the expression of a NB-LRR domain gene and reduces resistance to Phytophthora sojae.

MicroRNAs (miRNAs) are universal regulators that repress target gene expression in eukaryotes and play essential roles in plant immune responses. miRNAs were recently found to be involved in soybean and Phytophthora sojae interactions. Here, we screened miR1510, which was repressed in soybean during infection with P. sojae, indicating that it might be involved in soybean response to pathogens. To further uncover the roles of miRNAs in soybean, gma-miR1510a/b was overexpressed in the hairy roots of soybean using an Arabidopsis miR319a precursor as the backbone. The gma-miR1510a/b-overexpressing hairy roots showed enhanced susceptibility to P. sojae, and the results showed that miR1510 guides the cleavage of the Glyma.16G135500 gene, which encodes a classic type of plant disease resistance-associated gene that harbors the Toll-interleukin-like receptor (TIR) domain and nucleotide-binding site-leucine-rich repeat (NB-LRR) domain. Noticeably, several biotic stresses and hormone-responsive cis-regulatory elements were found to be present in the promoters of gma-MIR1510a and the target gene. Collectively, the results obtained in the current study reveal that gma-miR1510 regulates the target NB-LRR immune receptor gene Glyma.16G135500 and thus plays a crucial role in regulating the resistance of soybean to P. sojae.