Xie Xiaodong, Qin Guangyong, Si Ping, Luo Zhaopeng, Gao Junping, Chen Xia, Zhang Jianfeng, Wei Pan, Xia Qingyou, Lin Fucheng, Yang Jun
China Tobacco Gene Research Center, Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou, 450001, China.
College of Physical Engineering, Zhengzhou University, Zhengzhou, 450001, China.
Physiol Plant. 2017 Jun;160(2):222-239. doi: 10.1111/ppl.12547. Epub 2017 Mar 14.
The plant-specific PIN-FORMED (PIN) auxin efflux proteins have been well characterized in many plant species, where they are crucial in the regulation of auxin transport in various aspects of plant development. However, little is known about the exact roles of the PIN genes during plant development in Nicotiana species. This study investigated the PIN genes in tobacco (Nicotiana tabacum) and in two ancestral species (Nicotiana sylvestris and Nicotiana tomentosiformis). Genome-wide analysis of the N. tabacum genome identified 20 genes of the PIN family. An in-depth phylogenetic analysis of the PIN genes of N. tabacum, N. sylvestris and N. tomentosiformis was conducted. NtPIN4 expression was strongly induced by the application of exogenous indole-3-acetic acid (IAA), but was downregulated by the application of ABA, a strigolactone analogue, and cytokinin, as well as by decapitation treatments, suggesting that the NtPIN4 expression level is likely positively regulated by auxin. Expression analysis indicated that NtPIN4 was highly expressed in tobacco stems and shoots, which was further validated through analysis of the activity of the NtPIN4 promoter. We used CRISPR-Cas9 technology to generate mutants for NtPIN4 and observed that both T and T plants had a significantly increased axillary bud growth phenotype, as compared with the wild-type plants. Therefore, NtPIN4 offers an opportunity for studying auxin-dependent branching processes.
植物特有的PIN-FORMED（PIN）生长素输出蛋白在许多植物物种中已得到充分表征，它们在植物发育的各个方面对生长素运输的调节中起着关键作用。然而，关于PIN基因在烟草属植物发育过程中的具体作用却知之甚少。本研究调查了烟草（Nicotiana tabacum）以及两个祖先物种（森林烟草Nicotiana sylvestris和绒毛状烟草Nicotiana tomentosiformis）中的PIN基因。对烟草基因组进行全基因组分析，鉴定出了20个PIN家族基因。对烟草、森林烟草和绒毛状烟草的PIN基因进行了深入的系统发育分析。施加外源吲哚-3-乙酸（IAA）可强烈诱导NtPIN4的表达，但施加脱落酸、独脚金内酯类似物和细胞分裂素以及进行去顶处理后，NtPIN4的表达会下调，这表明NtPIN4的表达水平可能受生长素正向调控。表达分析表明，NtPIN4在烟草茎和芽中高度表达，通过对NtPIN4启动子活性的分析进一步证实了这一点。我们利用CRISPR-Cas9技术生成了NtPIN4突变体，观察到与野生型植株相比，T1和T2植株的腋芽生长表型均显著增加。因此，NtPIN4为研究生长素依赖性分枝过程提供了一个契机。
