Zhang Yan, Yang Xiaoqing, Cao Pei, Xiao Zheng'ang, Zhan Chang, Liu Meifeng, Nvsvrot Tashbek, Wang Nian
College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.
Hubei Engineering Technology Research Center for Forestry Information, Huazhong Agricultural University, Wuhan, China.
J Exp Bot. 2020 Jun 22;71(12):3485-3498. doi: 10.1093/jxb/eraa096.
Adventitious roots (ARs) are important for some plants that depend on clonal propagation. In this study, we demonstrate that a salt-responsive gene module is involved in the negative regulation of AR development in poplar. In this module, the expression of bZIP53 is induced by salt stress and it encodes a transcription factor with transactivation activity. Overexpression or induced expression of bZIP53 in poplar lines resulted in inhibition of AR growth, while heterologous overexpression of bZIP53 in Arabidopsis resulted in a similar phenotype. Results from RNA-seq and RT-qPCR assays predicted IAA4-1 and IAA4-2 to be downstream genes that were regulated by bZIP53. Further investigation of protein-DNA interactions using yeast one-hybrid, electrophoretic mobility shift, dual luciferase reporter, and GUS co-expression assays also showed that IAA4-1/2 were the genes that were directly regulated by bZIP53. Induced-expression IAA4-1/2 transgenic poplar lines also showed inhibited AR growth. In addition, both poplar bZIP53 and IAA4-1/2 showed a response to salt stress. On the basis of these results, we conclude that the bZIP53-IAA4 module is involved in the negative regulation of AR development in poplar.
不定根（ARs）对于一些依赖克隆繁殖的植物来说很重要。在本研究中，我们证明了一个盐响应基因模块参与杨树不定根发育的负调控。在这个模块中，bZIP53的表达受盐胁迫诱导，它编码一个具有反式激活活性的转录因子。在杨树品系中过表达或诱导表达bZIP53会导致不定根生长受到抑制，而在拟南芥中异源过表达bZIP53会产生类似的表型。RNA测序和逆转录定量聚合酶链反应（RT-qPCR）分析结果预测IAA4-1和IAA4-2是受bZIP53调控的下游基因。使用酵母单杂交、电泳迁移率变动分析、双荧光素酶报告基因分析和GUS共表达分析对蛋白质与DNA相互作用的进一步研究也表明，IAA4-1/2是受bZIP53直接调控的基因。诱导表达IAA4-1/2的转基因杨树品系也表现出不定根生长受到抑制。此外，杨树bZIP53和IAA4-又都对盐胁迫有响应。基于这些结果，我们得出结论，bZIP53-IAA4模块参与杨树不定根发育的负调控。
