植物科學(xué)研究權(quán)威期刊Plant Cell于7月9日在線發(fā)表植生生態(tài)所植物分子遺傳國家重點(diǎn)實(shí)驗(yàn)室陳曉亞研究組最新研究成果： miR156－靶基因SPL調(diào)控?cái)M南芥表皮毛的分布。
植物表皮毛覆蓋于植物地上組織的表面,，具有多種不同的生理功能,，有些還具有重要的經(jīng)濟(jì)價(jià)值，如棉纖維,。表皮毛的分布受到時(shí)空調(diào)控,。模式植物擬南芥在營養(yǎng)發(fā)育時(shí)期，表皮毛主要生長于蓮座葉的近軸面,；而當(dāng)植物進(jìn)入生殖發(fā)育期,，表皮毛的數(shù)量隨著花序軸的延伸而減少，直至花器官（除花萼外）基本無毛,。這一分布特征表明表皮毛發(fā)育的調(diào)控與植物發(fā)育的時(shí)相轉(zhuǎn)換有著密不可分的關(guān)系,。
SPL (SQUMOSA PROMOTER BINDING PROTEIN LIKE)基因編碼重要的轉(zhuǎn)錄因子。SPL家族的大部分成員是microRNA156的靶基因,，它們?cè)谥参镞M(jìn)入生殖生長期的時(shí)相轉(zhuǎn)換過程中起關(guān)鍵的調(diào)控作用,。過量表達(dá)miR156 (p35S::MIR156f)導(dǎo)致SPLs水平降低，花序軸上部和花柄器官均出現(xiàn)異位毛生長,；反之SPL基因高表達(dá)導(dǎo)致莖桿上表皮毛數(shù)量下降甚至光滑無毛,。在擬南芥表皮毛發(fā)育過程中，GL1-GL3-TTG1蛋白復(fù)合體正調(diào)控表皮毛發(fā)育,，而棉纖維發(fā)育也由類似復(fù)合體控制,。另一類單MYB轉(zhuǎn)錄因子TRICHOMELESS 1 (TCL1) 和TRIPTYCHON (TRY)在蛋白水平上與GL1競(jìng)爭(zhēng)結(jié)合GL3,，從而阻斷表皮毛發(fā)育。研究表明,，SPL9通過直接結(jié)合TCL1和TRY的啟動(dòng)子來激活這兩個(gè)負(fù)調(diào)控因子,，抑制表皮毛生長。上述結(jié)果表明,，受miR156調(diào)控的SPLs基因家族是連接植物發(fā)育進(jìn)程和表皮毛發(fā)育的橋梁,。棉花植物中miR156的含量很高，其對(duì)棉纖維發(fā)育的調(diào)控作用值得進(jìn)一步探討,。
該項(xiàng)工作得到了國家科技部,、國家自然科學(xué)基金委、中國科學(xué)院的經(jīng)費(fèi)支持,。(生物谷Bioon.net)
生物谷推薦原文出處：
Plant Cell doi：10.1105/tpc.109.072579
Temporal Control of Trichome Distribution by MicroRNA156-Targeted SPL Genes in Arabidopsis thaliana
Nan Yua,b,1, Wen-Juan Caia,b,1, Shucai Wangc, Chun-Min Shana,b, Ling-Jian Wanga and Xiao-Ya Chena,2
a National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, 200032 Shanghai, P.R. China
b Graduate School of Chinese Academy of Sciences, 200032 Shanghai, P.R. China
c Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
The production and distribution of plant trichomes is temporally and spatially regulated. After entering into the flowering stage, Arabidopsis thaliana plants have progressively reduced numbers of trichomes on the inflorescence stem, and the floral organs are nearly glabrous. We show here that SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) genes, which define an endogenous flowering pathway and are targeted by microRNA 156 (miR156), temporally control the trichome distribution during flowering. Plants overexpressing miR156 developed ectopic trichomes on the stem and floral organs. By contrast, plants with elevated levels of SPLs produced fewer trichomes. During plant development, the increase in SPL transcript levels is coordinated with the gradual loss of trichome cells on the stem. The MYB transcription factor genes TRICHOMELESS1 (TCL1) and TRIPTYCHON (TRY) are negative regulators of trichome development. We show that SPL9 directly activates TCL1 and TRY expression through binding to their promoters and that this activation is independent of GLABROUS1 (GL1). The phytohormones cytokinin and gibberellin were reported to induce trichome formation on the stem and inflorescence via the C2H2 transcription factors GIS, GIS2, and ZFP8, which promote GL1 expression. We show that the GIS-dependent pathway does not affect the regulation of TCL1 and TRY by miR156-targeted SPLs, represented by SPL9. These results demonstrate that the miR156-regulated SPLs establish a direct link between developmental programming and trichome distribution.
