Identification of a SMV Defense Response Gene GmNBL23 in Soybean

Soybean Mosaic Virus (SMV) is a plant virus that infects soybean worldwide, causing severe yield reductions. SMV also has the ability to systemically infect their host. While progress has been made on mapping of the SMV resistance locus, the gene itself is still unknown. NBS-LRR protein family members are key candidates as they underlie most disease genetic resistance found in plants to date. In our current efforts, we find SMV infection up-regulates the expression of miR-2 and miR-9. We also observe that some target genes of miR-2 and miR-9 are NBS-LRR family genes, including GmNBL23. Expression of GmNBL23 is induced 1 hr post SMV infection, however, it is repressed when SMV infection is established, which correlatives with expression of miR-2/9. Regulation of GmNBL23 by miR-2/9 was verified by RLM-RACE experiment and dual-luciferase assay. We hypothesize that GmNBL23 plays an important role in soybean resistance to SMV, and SMV antagonizes this resistance by up-regulating the level of miR-2/9. Currently, we are investigating the molecular mechanisms of SMV-soybean interaction by verifying the functions of GmNBL23 in SMV infection and the involvements of miR-2 and miR-9 during this process.