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 Research on miRNA biogenesis and post-transcriptional gene silencing directed by dsRNA-binding protein genes HYL1 and BcpLH, molecular mechanism of leaf curvature inflorescence transformation driven by the microRNA-directed genes encoding polarity, auxin response, and cell division, and analysis the genetic mechanism of leaf curvature in Brassica crops; identification of the genes responsible for plant resistance to heat, drought and cold, and molecular breeding of Brassica crops.
Principal Investigator: Dr. Yu-Ke He, Professor. Email: ykhe@sibs.ac.cn
Staff: Dr. Di-An Ni, Research Associate; Dr. Chuan-Bao Sun, Research Associate; Dr. Hai-Yan Duan, Research Assistant; Xiao-Rong Li, Research Intern; Wei-Li Zhong, Research Intern; Rui-Juan Shen, Senior Technician (emeritus)
Postdoctoral Fellows: Dr. Jin-Xin Liu
Graduate Students: Ye Jin; Shao-Feng Zhang; Yan-Fei Mao; Zhong-Yuan Liu; Lu Wang; Heng Lian; Han Wang; Xi Yang; Ya-Li Wang
Joint Graduate Student: Mai-Xia Hui (Northwest A & F University)
Graduated Student: Fei-Jie Wu, 2005 (PhD)
Regulation of BcpLH to Phase Transition of Vegetative Development of Chinese Cabbage
Vegetative development of Chinese cabbage (Brassica campestris ssp. pekinenesis) is divided into juvenile, intermediate and adult phases, corresponding to seedling, rosette and head stages, respectively. Proper transition between these phases is essential for production of edible heads. However, the genet basis of such transition and head formation has not been examined. Here we show that BcpLH (Brassica campestris ssp. pekinenesis LEAFY HEADS), a HYL1 homolog that we cloned from a cDNA library of Chinese cabbage by differential hybridization, is implicated in vegetative phase transition. In shoot apical meristem, expression of BcpLH gene is enhanced progressively with advancing phases. Silencing of BcpLH by its antisense construct disturbs transition of Chinese cabbage from juvenile phase to adult phase and interrupts head formation. Like HYL1, BcpLH-containing complex is able to process the miRNA precursor. Incurvature of leaves are consistently associated with reduced accumulation of miR165/166 and upregulation of adaxial identity genes REV (REVOLUTA), CNA and PHV (PHAVALOTA). We suggest that BcpLH is required for vegetative phase transition and head formation while mi165/166-guided post-transcriptional silencing is in concordance for maintenance of leaf identity.
Precise Regulation of MicroRNAs to Leaf Curvature of Brassica Crops
Chinese cabbage, pak-choi, cabbage, Brussels sprouts and kale, all belonging to Brassica genus, are characterized with the curved, wrinkle and curly leaves from where leafy heads that are important edible organs are composed. To examine the molecular mechanism of leaf curvature, we isolated BcpLH gene (Brassica campestris var. pekinensis LEAFY HEADS) that encodes a double-stranded RNA binding protein. We demonstrate that BcpLH, as the homolog of HYL1 in Arabidopsis, is required for microRNA biogenesis. The weak expression of BcpLH genes impairs the processing of miR165/166 and miR160, leading to the leaf curvature. Thus we propose that BcpLH plays a role in leaf curvature by alternative gene silencing regulated by microRNA pathway. In order to support this hypothesis, we cloned many Brassica homologs of BcpLH, microRNA and HD-Zip gene family such as REVOLUTA (REV), PHABULOSA (PHB), PHAVOLUTA (PHV), CORONA (CNA) and HB-8 from different accessions of Brassica species. Sequence analysis and functional complement experiments of the Brassica genes in Arabidopsis mutants reveal that the direction and extent of leaf curvature of Brassica crops are related to the mutation of some gene in pathway of microRNA Precise regulation of microRNAs to leaf curvature may be essential for formation of leafy heads.
Major Publications:
Wu F, Yu L, Cao W, Mao Y, Liu Z, He Y. (2007) The N-terminal double-stranded RNA binding domains of Arabidopsis HYPONASTIC LEAVES1 are sufficient for pre-MicroRNA processing. The Plant Cell 19: 914-925.
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