受體類激酶在植物生長發(fā)育和防御反應(yīng)中起著非常重要的作用。它們在非生物脅迫反應(yīng)中的作用研究較少,。
中科院遺傳與發(fā)育生物研究所張勁松課題組和陳受宜課題組的研究發(fā)現(xiàn),，水稻的一個(gè)具有S-結(jié)構(gòu)域的受體類激酶OsSIK2參與調(diào)控非生物脅迫反應(yīng)和衰老過程。OsSIK2定位于細(xì)胞質(zhì)膜,，在Mn2+存在下具有激酶活性,。OsSIK2基因主要在水稻葉片和葉鞘表達(dá)，其表達(dá)受鹽,、干旱,、冷害和植物激素ABA的誘導(dǎo)。過表達(dá)OsSIK2的水稻株系同對照株系相比呈現(xiàn)對鹽脅迫和干旱脅迫的耐性,。而突變體在這些脅迫處理后出現(xiàn)更加敏感的癥狀,。當(dāng)把OsSIK2的胞外域刪除之后，表達(dá)截短蛋白的株系呈現(xiàn)比表達(dá)全長蛋白的株系更高的耐鹽性(圖1),。
圖1,，OsSIK2轉(zhuǎn)基因水稻株系在鹽脅迫下的表現(xiàn)。OsSIK2-f是過表達(dá)OsSIK2全長基因的水稻株系,，OsSIK2-t是過表達(dá)截短基因（編碼去掉胞外域的OsSIK2）的水稻株系,。TP309為對照株系。結(jié)果顯示表達(dá)截短基因的水稻株系比表達(dá)全長基因的株系有更強(qiáng)的耐鹽性,。A,，處理前各水稻株系的表現(xiàn)。B,，0.5% NaCl處理3周后的表現(xiàn),。C，0.5% NaCl處理4周后的表現(xiàn),。D,，鹽處理后恢復(fù)3周的表現(xiàn)。
上述功能的差異可能是通過激活不同的下游基因引起的,。全長蛋白可增強(qiáng)PR類基因的表達(dá),，而截短蛋白可以促進(jìn)DREB類基因的表達(dá)。OsSIK2過表達(dá)株系還出現(xiàn)葉片發(fā)育早及黑暗誘導(dǎo)的衰老延遲的表型,。全長蛋白和截短蛋白激活的下游基因均受鹽脅迫,、干旱脅迫和黑暗處理的誘導(dǎo)。這些結(jié)果表明,，OsSIK2可能整合脅迫信號于發(fā)育過程從而使植物在不利環(huán)境條件下進(jìn)行適應(yīng)性生長,。
上述研究表明,，對于OsSIK2的改造和應(yīng)用可能有利于水稻和其它作物的改良和穩(wěn)產(chǎn)。該研究于10月18日在線發(fā)表于Plant Physiology,。張勁松課題組和陳受宜課題組共同培養(yǎng)的學(xué)生陳麗娟和哈達(dá)是這篇論文的共同第一作者,。
該項(xiàng)目得到“973”項(xiàng)目、國家自然科學(xué)基金,、中科院和轉(zhuǎn)基因?qū)ｍ?xiàng)資助,。（生物谷Bioon.com）
生物谷推薦的英文摘要
Plant Physiology doi：10.1104/pp.113.224881
An S-domain receptor-like kinase OsSIK2 confers abiotic stress tolerance and delays dark-induced leaf senescence in rice
Li-Juan Chen ， Hada Wuriyanghan ,， Yu-Qin Zhang ,， Kai-Xuan Duan ， Hao-Wei Chen ,， Qing-Tian Li ,， Xiang Lu ， Si-Jie He ,， Biao Ma ,， Wan-Ke Zhang， Qing Lin ,， Shou-Yi Chen and Jin-Song Zhang1
Receptor-like kinases (RLKs) play important roles in plant development and defense responses,； however， their functions in other processes remain unclear. Here,， we report that OsSIK2,， an S-domain RLK from rice， is involved in abiotic stress and senescence process. OsSIK2 is a plasma membrane-localized protein with kinase activity in the present of Mn2+. OsSIK2 is expressed mainly in rice leaf and sheath,， and can be induced by NaCl,， drought， cold,， dark and ABA treatment. Transgenic plants overexpressing OsSIK2 and mutant sik2 exhibit enhanced and reduced tolerance to salt and drought stress respectively compared to the controls. Interestingly,， a truncated version of OsSIK2 without most of extracellular region confers higher salt tolerance than the full-length OsSIK2,， likely through activation of different sets of downstream genes. Moreover,， seedlings of OsSIK2-overexpressing transgenic plants exhibit early leaf development and delayed dark-induced senescence phenotype， while mutant sik2 shows opposite phenotype. The downstream PR-related genes specifically up-regulated by full-length OsSIK2 or the DREB-like genes solely enhanced by truncated OsSIK2 are all induced by salt and dark treatments. These results indicate that OsSIK2 may integrate stress signals into developmental program for better adaptive growth under unfavorable conditions. Manipulation of OsSIK2 should facilitate improvement of production in rice and other crops.
