The root meristem growth factor BrRGF6 positively regulates Chinese cabbage to infection of clubroot disease caused by Plasmodiophora Brassicae


 Chinese cabbage has a high annual demand in China. However, clubroot disease caused by the infection of Plasmodiophora brassicae seriously affects its yield. Transcriptome analysis identified a root meristem growth factor 6 (BrRGF6) as significantly upregulated in Chinese cabbage roots infected with P. brassicae. Quantitative reverse-transcription polymerase chain reaction and in situ hybridization analysis showed higher BrRGF6 expression in susceptible materials than in resistant materials. After P. brassicae infection, BrRGF6 expression was significantly upregulated, especially in susceptible materials. Gene function analysis showed that the roots of Arabidopsis mutant rgf6 grew faster than the wild-type, and delayed the infection progress of P. brassicae. A Protein, nuclear transcription factor Y subunit C (BrNF-YC), was screened from yeast two-hybrid library of Chinese cabbage induced by P. brassicae, and verified to interact with BrRGF6 by yeast two-hybrid co-transfer. Yeast one-hybrid and β-Glucuronidase activity analysis showed that BrNF-YC could directly bind to and strongly activate the promoter of BrRGF6. Transgenic verification showed that BrRGF6 or BrNF-YC silenced Chinese cabbage significantly decreased the expression of BrRGF6, accelerated root development, and reduced incidence of clubroot disease. However, after overexpression of BrRGF6 or BrNF-YC, the phenotype showed a reverse trend. Therefore, BrRGF6 silencing accelerated root growth and enhanced resistance to clubroot disease, which was regulated by BrNF-YC.