Abstract
MicroRNA319a (miR319a) controls cell division arrest in plant leaves by inhibiting the expression of TCP (TEOSINTE BRANCHED 1/CYCLOIDEA/PCF) family genes. However, it is unclear whether miR319a influences infections by necrotrophic pathogens and host susceptibility. In this study, we revealed that miR319a affected plant resistance to stem rot disease of Sclerotinia sclerotiorum. In the plants of Brassica rapa infected with S. sclerotiorum, miR319a levels increased while expression levels of several BraTCP genes significantly decreased compared with those of the uninfected plants. The overexpression of BraMIR319a in B. rapa increased the susceptibility of the plants to S. sclerotiorum and aggravated stem rot disease, whereas the overexpression of BraTCP4-1 promoted the plant resistance. Our RNA-sequencing data revealed a potential relationship between miR319a and pathogen-related WRKY genes. Chromatin immunoprecipitation (ChIP) assay, electrophoretic mobility shift assay (EMSA) and reporter transaction assay showed that BraTCP4-1 was bound to the promoters of WRKY75, WRKY70, and WRKY33 genes and directly activated these pathogen-related genes. Moreover, the expression levels of WRKY75, WRKY70, and WRKY33 in the plants overexpressing BraMIR319a declined significantly whereas those of the plants overexpressing BraTCP4-1 increased significantly. These results suggest that miR319a and its targeted gene BraTCP4 regulate stem rot resistance through pathways of WRKY genes.
New tools for characterizing early brown stem rot disease resistance signaling in soybean