庇蔭反應(shade avoidance syndrome)是植物在光信號的刺激下基因調控模式的改變而形成的發育進程變化,其背後的分子機理一直是發育生物學研究領域的熱點。此外,密植條件下光對植物生長發育的調控影響到作物生長以及最終產量。一直從事光生物學與作物理想株型分子設計方面研究的,中國農科院生物技術所研究員王海洋團隊最近發現,擬南芥的庇蔭反應是PIFs抑制MIR156的表達來實現的。
PIFs(PHYTOCHROME-INTERACTING FACTORS)是擬南芥中的一類光敏色素受體,在庇蔭反應中起著重要的調控作用。MIR156是植物MicroRNA家族的重要成員,參與了很多植物發育過程。研究人員發現,超表達PIFs蛋白會增強植物在遮蔭下(高紅光:遠紅光比率)的庇蔭反應,而超表達MIR156會得到相反的結果。體內和體外的試驗顯示,PIFs蛋白會直接結合到MIR156基因啟動子的G-box區域,抑制MIR156基因的表達,而MIR156會抑制SPL(SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE)家族基因來調控植物株高、葉片發育、開花期等各種與庇蔭反應相關的發育過程。
該研究理清了phy-PIFs和miR156-SPL的調控路徑,完善了庇蔭反應的分子機理,為下一步耐密植作物的培育奠定了理論基礎。
Nature Communications, 8: 348, 24 August 2017
Phytochrome-interacting factors directly suppress MIR156 expression to enhance shade-avoidance syndrome in Arabidopsis
Author
Yurong Xie, Yang Liu, Hai Wang, Xiaojing Ma, Baobao Wang, Guangxia Wu & Haiyang Wang*
*: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, China
Abstract
Plants have evolved are pertoire of strategies collectively termed the shade-avoidance syndrome to avoid shade from canopy and compete for light with their neighbors. However, the signaling mechanism governing the adaptive changes of adult plant architecture to shade is not well understood. Here, we show that in Arabidopsis, compared with the wild type, several PHYTOCHROME-INTERACTING FACTORS (PIFS) overexpressors all display constitutive shade-avoidance syndrome under normal high red to far-redlight ratio conditions but are less sensitive to the simulated shade, whereas the MIR156 overexpressors exhibit an opposite phenotype. The simulated shade induces rapid accumulation of PIF proteins, reduced expression of multiple MIR156 genes, and concomitant elevated expression of the SQUAMOSA-PROMOTER BINDINGPROTEIN-LIKE (SPL) family genes. Moreover, in vivo and in vitro assays indicate that PIFs bind to the promoters of several MIR156 genes directly and repress their expression. Our results establish a direct functional link between the phytochrome-PIFs and miR156-SPL regulatory modules in mediating shade-avoidance syndrome.
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