Genome-Wide Identification And Analysis Of The Valine-Glutamine Motif-Containing Gene Family In Brassica Napus And Functional Characterization Of Bnmks1 In Response To Leptosphaeria Maculans

Proteins containing valine-glutamine (VQ) motifs play important roles in plant growth and development as well as in defense responses to both abiotic and biotic stresses. Blackleg disease, which is caused by Leptosphaeria maculans, is the most important disease in canola (Brassica napus) worldwide; however, the identification of Brassica napus VQs and their functions in response to blackleg disease have not yet been reported. In this study, we conducted a genome-wide identification and characterization of the VQ gene family in Brassica napus, including chromosome location, phylogenetic relations, gene structure, motif domain, synteny analysis, and cis-elements categorization of their promoter regions. To understand Brassica napus VQ gene function in response to blackleg disease, we overexpressed BnVQ7 (BnaA01g36880D, also known as the mitogen-activated protein kinase 4 substrate 1 [MKS1] gene) in a blacklegsusceptible canola variety, Westar. Overexpression of BnMKS1 in canola did not improve its resistance to blackleg disease at the seedling stage; however, transgenic canola plants overexpressing BnMKS1 displayed an enhanced resistance to L. maculans infection at the adult plant stage. Expression levels of downstream and defense marker genes in cotyledons increased significantly at the necrotrophic stage of L. maculans infection in the overexpression line of BnMKS1, suggesting that the salicylic acid- and jasmonic acid-mediated signaling pathways were both involved in the defense responses. Together, these results suggest that BnMKS1 might play an important role in defense against L. maculans.