版纳植物园揭示基因MYB82调控表皮发育机制

表皮毛由植物表皮细胞发育而来，广泛分布于陆生植物，是生长在植物表皮组织的一种特化结构。叶片表皮毛可以起到保护叶片、防止强光灼伤、减小蒸腾的作用。有些植物的表皮毛可以分化成腺毛从而分泌一些次生代谢物质更好地保护植物。

表皮毛的起始和形成受到细胞内基因的程序性调控。目前的研究表明，由三个不同基因家族蛋白形成的WD40/bHLH/MYB调控复合物是调控表皮毛起始和形成的关键因子，其中任何一个蛋白功能的缺失都会导致植物无法形成表皮毛。GL1(GLABROUS 1)和GL3(GLABROUS 3)分别是拟南芥中调控表皮毛形成的一个MYB基因和一个bHLH基因，它们各自的功能缺失都会导致植物产生光滑的叶片。

中国科学院西双版纳热带植物园植物分子生物学研究组副研究员梁岗和博士研究生何华、李扬在拟南芥里鉴定了一个GL1的同源基因MYB82，该基因在叶片的新生表皮毛中有较强的表达。通过分析MYB82基因的过表达以及显性抑制转基因植物，发现MYB82正调控表皮毛的发育。

MYB82突变体并没有影响表皮毛的发育，表明MYB82与其他MYB基因冗余地调控表皮毛的发育。进一步分析发现，MYB82蛋白可以和GL3蛋白形成复合物，表明MYB82是WD40/bHLH/MYB调控复合物中的一个成员蛋白。

该研究成果已经在JouRNAl of Experimental Botany上在线发表。研究由国家青年科学基金资助完成。

原文摘要：

MYB82 functions in regulation of trichome development in Arabidopsis

Gang Liang, Hua He, Yang Li, Qin Ai and DIQiu Yu

Trichome initiation and patterning are controlled by the TTG1–bHLH–MYB regulatory complex. Several MYB transcription factors have been determined to function in trichome development via incorporation into this complex. This study examined the role of MYB82, an R2R3-MYB transcription factor, in Arabidopsis trichome development. MYB82 was revealed to be a nuclear-localized transcription activator. Suppression of MYB82 function by fusion with a dominant repression domain (SRDX) resulted in glabrous leaves, as did overexpression of N-terminal-truncated MYB82. Overexpression of MYB82 genomic sequence, but not its cDNA sequence, led to reduced trichome numbers. Further investigation indicated that at least one of the two introns in MYB82 is essential to the protein’s trichome developmental function. An MYB-binding box was identified in the third exon of MYB82, which was inferred to be crucial for MYB82 function because the mutation of this box interfered with the ability of MYB82 to rescue the gl1 mutant. Protein interaction analysis revealed that MYB82 physically interacts with GLABRA3 (GL3). In addition, MYB82 and GL1 can form homodimers and heterodimers at R2R3-MYB domains, which may explain why their overexpression reduces trichome numbers. These results demonstrate the functional diversification of MYB82 and GL1 in trichome development.

作者：中科院