microRNA528 Affects Lodging Resistance of Maize by Regulating Lignin Biosynthesis under Nitrogen-Luxury Conditions
作 者：Qing Sun, Xiaogang Liu, Juan Yang, Wenwen Liu, Qingguo Du, Hongqiu Wang, Chunxiang Fu, Wen-Xue L
刊物名称： MOLECULAR PLANT
出版年份：18 March 2018
Lodging under N-luxury conditions substantially reduces crop yield and seed quality. However, the molecular mechanisms of plant lodging resistance remain largely unclear, especially in maize. We report here that the expression of ZmmiR528, a monocot-specific miRNA, is induced by nitrogen (N) luxury but reduced by N deficiency. Thioacidolysis and acetyl bromide (AcBr) analysis showed that N luxury significantly reduced the generation of H, G, and S monomers and the total lignin content of maize shoots. We further demonstrated that ZmLACCASE3 (ZmLAC3) and ZmLACCASE5 (ZmLAC5) are the targets of ZmmiR528. In situ hybridization showed that ZmmiR528 is mainly expressed in the vascular tissues in maize. Knock-down ZmmiR528 significantly increased the lignin content and rind penetrometer resistance in maize stems. In contrast, transgenic maize overexpressing ZmmiR528 had reduced lignin content and rind penetrometer resistance and was prone to lodging under N-luxury conditions. Overexpression of ZmLAC3 increased maize lignin contents and rind penetrometer. RNA-seq analysis indicated that ZmPAL7 and ZmPAL8 are upregulated in ZmmiR528 knock-down transgenic maize. Under N-luxury conditions, the expression levels of ZmPALs were much higher in ZmmiR528 knock-down transgenic maize than in WT and ZmmiR528 OE transgenic maize. The results indicate that, by regulating the expression of ZmLAC3 and ZmLAC5, ZmmiR528 affects maize lodging resistance under N-luxury conditions.