Cloning of miR164b precursor from Phyllostachys edulis and analysis of its function in leaf morphogenesis

MicroRNA (miRNA) plays a crucial role in the regulation of plant morphogenesis by participating in a variety of physiological metabolic processes.The miR164 family is a group of plant-specific miRNAs,whose target genes are mainly the NAC transcription factors involved in the differentiation and development of apical meristems in stems and leaves,as well as in plant senesce.In this study,the precursor sequence of miR164b isolated from Phyllostachys edulis was 82 bp,which could form a stable stem-loop structure with the generated mature sequence on the 5'end of the arm.The mature sequences of the miR164 family were highly conserved.The expression vector with the target fragment harboring the miR164b precursor driven by CaMV 35S was constructed and transformed into Arabidopsis(Col-0).The phenotypes demonstrated that the transgenic Arabidopsis plants grew smaller and weaker,with fewer leaves,later flowering,and smoother leaf margins than those of Col-0.The real-time PCR results showed that the expression of miR164b was significantly increased (P < 0.01) and the expressions of CUC1 and CUC2 were significantly down-regulated (P < 0.01) in transgenic plants compared with Col-0.These results indicate that miR164b plays an important role in leaf morphogenesis by regulating the expression of CUC1 and CUC2.This study provides a useful reference for bamboo molecular breeding using miRNA strategies.