JIPB | ​万建民院士团队在水稻粒型调控上取得重要进展Plant J：组氨酸磷酸转运蛋白AHP4在拟南芥对干旱胁迫的反应中起负向调控作用

今天介绍的是由日本科学家在Plant J上发表的研究论文《The histidine phosphotransfer AHP4 plays a negative role in Arabidopsis plant response to drought》。

细胞分裂素通过多信号转导通路在植物逆境反应中发挥重要作用，其中涉及组氨酸磷酸转移蛋白(HPS)。在拟南芥中，已知AHP2、AHP3和AHP5蛋白会影响干旱反应；但AHP4在干旱适应中的作用尚不确定。在本研究中，作者用基因功能丧失的方法证明了AHP4在拟南芥对干旱胁迫的反应中具有重要的作用。在干旱条件下，ahp4植株的存活率高于野生型(WT)植株并伴随着野生型(WT)植株中AHP4表达的下调可以证明上述说法。后对ahp4和WT植株的转录组比较分析表明，ahp4介导了几个脱水以及脱落酸(ABA)应答基因的表达过程，这些基因参与植物适应干旱的各种生理生化过程的调节。与WT相比，ahp4植株茎中植物蜡质积累增加，叶片角质层增厚，且萌发时对外源ABA更敏感，气孔狭窄，脱水过程中叶温升高，在渗透胁迫下根长度增加。此外，与WT相比，aph4植株在干旱条件下表现出更高的光合作用效率、更低的ROS水平、电解质渗漏反应和膜脂过氧化作用减轻以及更高的花青素含量。在ahp4植物中会表现出的这些差异可能是由于编码参与ROS清除和非酶抗氧化剂代谢的酶的基因上调所致。总体而言，作者的发现表明AHP4在植物干旱适应中发挥着关键作用。

Cytokinin plays an important role in plant stress responses via a multistep signaling pathway, involving the histidine phosphotransfer proteins (HPs). InArabidopsis thaliana, the AHP2, AHP3 and AHP5 proteins are known to impact drought responses; however, the role of AHP4 in drought adaptation remains undetermined. In the present study, using a loss-of-function approach we showed that AHP4 possesses an important role in Arabidopsis’s response to drought. This is evidenced by the higher survival rates of ahp4 than wild-type (WT) plants under drought conditions which is accompanied by the down-regulated AHP4 expression in WT during periods of dehydration. Comparative transcriptome analysis of ahp4 and WT plants revealed AHP4-mediated expression of several dehydration- and/or abscisic acid (ABA)-responsive genes involved in regulation of various physiological and biochemical processes important for plant drought acclimation. In comparison with WT, ahp4 plants showed increased wax crystal accumulation in stems, thicker cuticles in leaves, greater sensitivity to exogenous ABA at germination, narrow stomatal apertures, heightened leaf temperatures during dehydration, and longer root length under osmotic stress. Additionally, ahp4 plants showed greater photosynthetic efficiency, lower levels of reactive oxygen species (ROS), reduced electrolyte leakage and lipid peroxidation, and increased anthocyanin contents under drought, when compared with WT. These differences displayed in ahp4 plants are likely due to up-regulation of genes that encode enzymes involved in ROS-scavenging and non-enzymatic antioxidant metabolism. Overall, our findings suggest that AHP4 plays a crucial role in plant drought adaptation.

原文链接：https://doi.org/10.1111/tpj.15920

转自：植物科学SCI

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