Rowe James H, Topping Jennifer F, Liu Junli, Lindsey Keith
The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
New Phytol. 2016 Jul;211(1):225-39. doi: 10.1111/nph.13882. Epub 2016 Feb 18.
Understanding the mechanisms regulating root development under drought conditions is an important question for plant biology and world agriculture. We examine the effect of osmotic stress on abscisic acid (ABA), cytokinin and ethylene responses and how they mediate auxin transport, distribution and root growth through effects on PIN proteins. We integrate experimental data to construct hormonal crosstalk networks to formulate a systems view of root growth regulation by multiple hormones. Experimental analysis shows: that ABA-dependent and ABA-independent stress responses increase under osmotic stress, but cytokinin responses are only slightly reduced; inhibition of root growth under osmotic stress does not require ethylene signalling, but auxin can rescue root growth and meristem size; osmotic stress modulates auxin transporter levels and localization, reducing root auxin concentrations; PIN1 levels are reduced under stress in an ABA-dependent manner, overriding ethylene effects; and the interplay among ABA, ethylene, cytokinin and auxin is tissue-specific, as evidenced by differential responses of PIN1 and PIN2 to osmotic stress. Combining experimental analysis with network construction reveals that ABA regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin.
了解干旱条件下调节根系发育的机制是植物生物学和全球农业面临的一个重要问题。我们研究了渗透胁迫对脱落酸（ABA）、细胞分裂素和乙烯反应的影响，以及它们如何通过对PIN蛋白的作用来介导生长素运输、分布和根系生长。我们整合实验数据以构建激素相互作用网络，从而形成多种激素对根系生长调节的系统观点。实验分析表明：在渗透胁迫下，依赖ABA和不依赖ABA的应激反应都会增加，但细胞分裂素反应仅略有降低；渗透胁迫下根系生长的抑制不需要乙烯信号传导，但生长素可以挽救根系生长和分生组织大小；渗透胁迫调节生长素转运蛋白的水平和定位，降低根系生长素浓度；在胁迫下，PIN1水平以依赖ABA的方式降低，从而优先于乙烯的作用；PIN1和PIN2对渗透胁迫的不同反应证明，ABA、乙烯、细胞分裂素和生长素之间的相互作用具有组织特异性。将实验分析与网络构建相结合表明，ABA通过与细胞分裂素、乙烯和生长素相互作用的激素网络来调节渗透胁迫条件下的根系生长。
