Molecular Mechanism of NF-YC15 Transcription Factor in Regulating Resistance to Bacterial Blight of Cassava

Objective Molecular mechanism of NF-YC15 transcription factor associated with the regulation of bacterial blight resistance of Manihot esculenta was investigated.

Methods Yeast two-hybrid was employed to determine the interacting proteins with the MeNF-YC15 transcription factor. Bimolecular fluorescence complementation and pull-down experiments were conducted to verify the interactions. On overexpressed cassava, bacterial blight pathogens were inoculated to study disease resistance of the plant. Through transcriptome sequencing, downstream disease-resistant genes regulated by MeNF-YC15 were identified, and the molecular mechanism analyzed by quantitative PCR.

Results The key inhibitor of jasmonic acid ZIM domain protein MeJAZ2.2 in the signal transduction pathway was identified to be the sole protein interacting with MeNF-YC15, which was further verified in vivo and in vitro in plants. The bacteria and disease lesion areas on the significantly taller MeNF-YC15-overexpressed plants were significantly smaller than those on the MeNF-YC15-MeJAZ2.2-co-overexpressed counterparts and control. MeNF-YC15 activated the downstream disease resistant WRKY68, matrix metalloproteinase-3 (MMP-3), and leucine-rich repeat receptor-like kinases (LRR-RLK) of jasmonic acid, and in contrast, MeJAZ2.2 inhibited the expressions.

Conclusion MeNF-YC15 and MeJAZ2.2 antagonistically regulated the expression of downstream disease-resistant genes of jasmonic acid and the resistance of cassava plant to the bacterial blight through the jasmonic acid pathway.