華中農(nóng)業(yè)大學(xué)研究人員在水稻基礎(chǔ)研究領(lǐng)域又取得了一項重大研究成果,?？蒲腥藛T從水稻中分離出了一個可以控制不定根生長發(fā)育的關(guān)鍵調(diào)節(jié)因子基因WOX11,，從而揭示出水稻不定根發(fā)育的調(diào)控機理,。
根在植物生長發(fā)育中具有重要作用,，以致有俗語形象的稱“本固枝榮”,。據(jù)介紹,，水稻根系主要由大量的不定根及其側(cè)根組成,，其中不定根是水稻起固著、吸收養(yǎng)分和水分的主要器官,，是決定水稻生長,、產(chǎn)量和抗性的重要因子。
課題組分離出一個可以控制不定根生長發(fā)育的關(guān)鍵調(diào)節(jié)因子基因WOX11,，該基因通過介導(dǎo)植物生長素和細胞分裂素的信號傳導(dǎo)來調(diào)控水稻不定根的生長發(fā)育,。它的完全缺失或下降表達會引起水稻不定根減少；超量表達可以使水稻不定根的數(shù)量大量增加,，并且在正常的生長條件下,，水稻莖的每個節(jié)上都會生長數(shù)量不等的不定根,，甚至小花的基部也會生長1-2條異位根。研究發(fā)現(xiàn)該基因是植物所特有,。
課題組專家周道繡介紹說,，研究成果為分子育種提供了重要的理論依據(jù)和基因資源；同時,，由于其形態(tài)結(jié)構(gòu)和進化上的特殊性,，根在植物器官發(fā)育的研究中是一個非常理想的模式器官，我們進一步豐富了植物器官發(fā)育的理論知識,，將使人們對植物根的功能有更新的認識,。
長期以來，育種學(xué)家在選育優(yōu)良水稻品種時關(guān)注更多的是植株地上部分的有關(guān)形態(tài)和生理性狀,，但對水稻根系這一極為重要器官的形態(tài),、生理性狀的改良卻未能在水稻的育種計劃中得到具體體現(xiàn)。水稻根系發(fā)育性狀的遺傳研究相對滯后,，對水稻根系性狀遺傳規(guī)律的認識和了解比較缺乏,，限制了它在育種中的應(yīng)用。
據(jù)悉,，該研究成果于3月4日在國際植物生物學(xué)研究領(lǐng)域的頂級雜志The Plant Cell在線發(fā)表,。（生物谷Bioon.com）
生物谷推薦原始出處：
The Plant Cell March 3, 2009; 10.1105/tpc.108.061655
The WUSCHEL-Related Homeobox Gene WOX11 Is Required to Activate Shoot-Borne Crown Root Development in Rice
Yu Zhao 1, Yongfeng Hu 1, Mingqiu Dai 1, Limin Huang 1, and Dao-Xiu Zhou 2*
1 National Key Laboratory for Crop Genetic Improvement, Huazhong Agricultural University, 430070 Wuhan, China
2 Institut de Biotechnologie des Plantes, Université Paris Sud 11, 91405 Orsay, France
In rice (Oryza sativa), the shoot-borne crown roots are the major root type and are initiated at lower stem nodes as part of normal plant development. However, the regulatory mechanism of crown root development is poorly understood. In this work, we show that a WUSCHEL-related Homeobox (WOX) gene, WOX11, is involved in the activation of crown root emergence and growth. WOX11 was found to be expressed in emerging crown roots and later in cell division regions of the root meristem. The expression could be induced by exogenous auxin or cytokinin. Loss-of-function mutation or downregulation of the gene reduced the number and the growth rate of crown roots, whereas overexpression of the gene induced precocious crown root growth and dramatically increased the root biomass by producing crown roots at the upper stem nodes and the base of florets. The expressions of auxin- and cytokinin-responsive genes were affected in WOX11 overexpression and RNA interference transgenic plants. Further analysis showed that WOX11 directly repressed RR2, a type-A cytokinin-responsive regulator gene that was found to be expressed in crown root primordia. The results suggest that WOX11 may be an integrator of auxin and cytokinin signaling that feeds into RR2 to regulate cell proliferation during crown root development.
