State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, China.
Plant Biotechnol J. 2015 Aug;13(6):833-48. doi: 10.1111/pbi.12320. Epub 2015 Jan 20.
Potassium (K) deficiency in plants confines root growth and decreases root-to-shoot ratio, thus limiting root K acquisition in culture medium. A WUSCHEL-related homeobox (WOX) gene, WOX11, has been reported as an integrator of auxin and cytokinin signalling that regulates root cell proliferation. Here, we report that ectopic expression of WOX11 gene driven by the promoter of OsHAK16 encoding a low-K-enhanced K transporter led to an extensive root system and adventitious roots and more effective tiller numbers in rice. The WOX11-regulated root and shoot phenotypes in the OsHAK16p:WOX11 transgenic lines were supported by K-deficiency-enhanced expression of several RR genes encoding type-A cytokinin-responsive regulators, PIN genes encoding auxin transporters and Aux/IAA genes. In comparison with WT, the transgenic lines showed increases in root biomass, root activity and K concentrations in the whole plants, and higher soluble sugar concentrations in roots particularly under low K supply condition. The improvement of sugar partitioning to the roots by the expression of OsHAK16p:WOX11 was further indicated by increasing the expression of OsSUT1 and OsSUT4 genes in leaf blades and several OsMSTs genes in roots. Expression of OsHAK16p:WOX11 in the rice grown in moderate K-deficient soil increased total K uptake by 72% and grain yield by 24%-32%. The results suggest that enlarging root growth and development by the expression of WOX11 in roots could provide a useful option for increasing K acquisition efficiency and cereal crop productivity in low K soil.
植物中的钾（K）缺乏会限制根系生长并降低根冠比，从而限制了在培养基中对根的 K 吸收。已经报道了一个与 WUSCHEL 相关的同源盒（WOX）基因 WOX11，它作为生长素和细胞分裂素信号的整合因子，调节根细胞的增殖。在这里，我们报告说，由编码低 K 增强型 K 转运体的 OsHAK16 启动子驱动的 WOX11 基因的异位表达导致了水稻广泛的根系和不定根以及更有效的分蘖数。在 OsHAK16p:WOX11 转基因系中，WOX11 调节的根和地上部表型得到了 K 缺乏增强表达的几个 RR 基因（编码 A 型细胞分裂素反应调节剂）、编码生长素转运体的 PIN 基因和 Aux/IAA 基因的支持。与 WT 相比，转基因系表现出根生物量、根活力和整株植物中 K 浓度的增加，特别是在低 K 供应条件下，根中的可溶性糖浓度更高。通过表达 OsHAK16p:WOX11 向根部分配更多的糖进一步表明，叶片中 OsSUT1 和 OsSUT4 基因以及根中几个 OsMSTs 基因的表达增加。在中度低钾土壤中生长的水稻中表达 OsHAK16p:WOX11 增加了 72%的总 K 吸收量和 24%-32%的籽粒产量。结果表明，通过在根中表达 WOX11 来扩大根的生长和发育，可以为提高低钾土壤中 K 吸收效率和谷类作物生产力提供一种有用的选择。
