华中农业大学研究人员在水稻基础研究领域又取得了一项重大研究成果。科研人员从水稻中分离出了一个可以控制不定根生长发育的关键调节因子基因WOX11，从而揭示出水稻不定根发育的调控机理。
根在植物生长发育中具有重要作用，以致有俗语形象的称“本固枝荣”。据介绍，水稻根系主要由大量的不定根及其侧根组成，其中不定根是水稻起固着、吸收养分和水分的主要器官，是决定水稻生长、产量和抗性的重要因子。
课题组分离出一个可以控制不定根生长发育的关键调节因子基因WOX11，该基因通过介导植物生长素和细胞分裂素的信号传导来调控水稻不定根的生长发育。它的完全缺失或下降表达会引起水稻不定根减少；超量表达可以使水稻不定根的数量大量增加，并且在正常的生长条件下，水稻茎的每个节上都会生长数量不等的不定根，甚至小花的基部也会生长1-2条异位根。研究发现该基因是植物所特有。
课题组专家周道绣介绍说，研究成果为分子育种提供了重要的理论依据和基因资源；同时，由于其形态结构和进化上的特殊性，根在植物器官发育的研究中是一个非常理想的模式器官，我们进一步丰富了植物器官发育的理论知识，将使人们对植物根的功能有更新的认识。
长期以来，育种学家在选育优良水稻品种时关注更多的是植株地上部分的有关形态和生理性状，但对水稻根系这一极为重要器官的形态、生理性状的改良却未能在水稻的育种计划中得到具体体现。水稻根系发育性状的遗传研究相对滞后，对水稻根系性状遗传规律的认识和了解比较缺乏，限制了它在育种中的应用。
据悉，该研究成果于3月4日在国际植物生物学研究领域的顶级杂志The Plant Cell在线发表。（生物谷Bioon.com）
生物谷推荐原始出处：
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.
