Han Yao, Xin Mingming, Huang Ke, Xu Yuyun, Liu Zhenshan, Hu Zhaorong, Yao Yingyin, Peng Huiru, Ni Zhongfu, Sun Qixin
State Key Laboratory for Agrobiotechnology and Key Laboratory of Crop Heterosis and Utilization (MOE) and Key Laboratory of Crop Genomics and Genetic Improvement (MOA), Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Yuanmingyuan Xi Road No. 2, Haidian District, Beijing, 100193, China.
New Phytol. 2016 Jan;209(2):721-32. doi: 10.1111/nph.13615. Epub 2015 Sep 3.
Polyploidy is a major driving force in plant evolution and speciation. Phenotypic changes often arise with the formation, natural selection and domestication of polyploid plants. However, little is known about the consequence of hybridization and polyploidization on root hair development. Here, we report that root hair length of synthetic and natural allopolyploid wheats is significantly longer than those of their diploid progenitors, whereas no difference is observed between allohexaploid and allotetraploid wheats. The expression of wheat gene TaRSL4, an orthologue of AtRSL4 controlling the root hair development in Arabidopsis, was positively correlated with the root hair length in diploid and allotetraploid wheats. Moreover, transcript abundance of TaRSL4 homoeologue from A genome (TaRSL4-A) was much higher than those of other genomes in natural allopolyploid wheat. Notably, increased root hair length by overexpression of the TaRSL4-A in wheat led to enhanced shoot fresh biomass under nutrient-poor conditions. Our observations indicate that increased root hair length in allohexaploid wheat originated in the allotetraploid progenitors and altered expression of TaRSL4 gene by genome interplay shapes root hair length in allopolyploid wheat.
多倍体是植物进化和物种形成的主要驱动力。表型变化通常伴随着多倍体植物的形成、自然选择和驯化而出现。然而，关于杂交和多倍体化对根毛发育的影响却知之甚少。在此，我们报道，人工合成和天然异源多倍体小麦的根毛长度显著长于其二倍体祖先，而异源六倍体小麦和异源四倍体小麦之间未观察到差异。小麦基因TaRSL4是拟南芥中控制根毛发育的AtRSL4的同源基因，其表达与二倍体和异源四倍体小麦的根毛长度呈正相关。此外，在天然异源多倍体小麦中，来自A基因组的TaRSL4同源基因（TaRSL4-A）的转录丰度远高于其他基因组。值得注意的是，在小麦中过表达TaRSL4-A导致根毛长度增加，在营养贫瘠条件下地上部鲜生物量增加。我们的观察结果表明，异源六倍体小麦根毛长度的增加起源于异源四倍体祖先，并且基因组间相互作用导致TaRSL4基因表达改变，从而塑造了异源多倍体小麦的根毛长度。
