Browse Articles

Article|01 Jan 2020|OPEN
BcpLH organizes a specific subset of microRNAs to form a leafy head in Chinese cabbage (Brassica rapa ssp. pekinensis)
Wenqing Ren1,2, Feijie Wu1, Jinjuan Bai1, Xiaorong Li1, Xi Yang1, Wanxin Xue1, Heng Liu1,3, & Yuke He1,
1National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Fenglin Road 300, Shanghai 200032, China
2Graduate School of the Chinese Academy of Sciences, Shanghai 200032, China
3South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Sciences, Ministry of Agriculture, Zhanjiang, Guangdong, China

Horticulture Research 7,
Article number: 20001 (2020)
doi: 10.1038/hortres.2020.1
Views: 433

Received: 20 Aug 2019
Revised: 07 Oct 2019
Accepted: 24 Oct 2019
Published online: 01 Jan 2020

Abstract

HYL1 (HYPONASTIC LEAVES 1) in Arabidopsis thaliana encodes a double-stranded RNA-binding protein needed for proper miRNA maturation, and its null mutant hyl1 shows a typical leaf-incurvature phenotype. In Chinese cabbage, BcpLH (Brassica rapa ssp. pekinensis LEAFY HEADS), a close homolog of HYL1, is differentially expressed in juvenile leaves, which are flat, and in adult leaves, which display extreme incurvature. BcpLH lacks protein–protein interaction domains and is much shorter than HYL1. To test whether BcpLH is associated with defects in microRNA (miRNA) biogenesis and leaf flatness, we enhanced and repressed the activity of BcpLH by transgenics and investigated BcpLH-dependent miRNAs and plant morphology. BcpLH promoted miRNA biogenesis by the proper processing of primary miRNAs. BcpLH downregulation via antisense decreased a specific subset of miRNAs and increased the activities of their target genes, causing upward curvature of rosette leaves and early leaf incurvature, concurrent with the enlargement, earliness, and round-to-oval shape transition of leafy heads. Moreover, BcpLH-dependent miRNAs in Chinese cabbage are not the same as HYL1-dependent miRNAs in Arabidopsis. We suggest that BcpLH controls a specific subset of miRNAs in Chinese cabbage and coordinates the direction, extent, and timing of leaf curvature during head formation in Brassica rapa.