Transcriptional analysis of different mulberry cultivars in response to Ralstonia solanacearum

Abstract

Bacterial wilt caused by Ralstonia solanacearum is a major disease of the mulberry (Morus atropurpurea Roxb.), resulting in severe yield and quality losses. However, little is known about the molecular mechanisms of resistance. Using the RNA sequencing technique, we identified early transcriptional changes in resistant (KQ10 and YS283) and susceptible (YSD10) mulberry cultivars in response to R. solanacearum infection. We observed that 798 genes were differentially and specifically regulated in both resistant cultivars but not in the susceptible cultivar after infection with R. solanacearum, including 502 upregulated and 296 downregulated genes. Among the differentially expressed genes, 31 encode transcription factors and 48 encode protein kinases. Interestingly, we found that a large number of genes (61) associated with cell-wall modification were differentially and specifically regulated in the resistant cultivars. These genes could be divided into 10 major groups. The largest group is the glucosyltransferase family, followed by the pectinesterase inhibitor, glucanase, and glycoprotein families, suggesting that cell-wall modifications may play an important role in resistance levels in mulberry. This transcriptional analysis paves the way for elucidating the molecular mechanisms of the resistance response to R. solanacearum in mulberry.