欧亚国际

科学家刚刚利用Plantarray植物功能生理表型系统，发表了题为“Guard cell activity of PIF4 and HY5 control transpiration”的文章，文章发表于期刊Plant Science。

Plantarray是一款基于称重的高通量、多传感器生理表型平台以及植物逆境生物学研究通用平台。该系统可持续、实时测量位于不同环境条件下、阵列中每个植株的土壤-植物-空气（SPAC）中的即时水流动。直接测量根系和茎叶系统水平衡和生物量增加，计算植物生理参数以及植物对动态环境的反馈。系统以有效、易用、无损的方式针对植物对不同处理的反应、预测植物生长和生产力进行定量比较，广泛应用于生物胁迫和非生物胁迫以及植物栽培加速育种研究等，胁迫研究涵盖干旱胁迫、盐胁迫、重金属胁迫、热、冷胁迫、光胁迫以及灌溉/养分、CO2指示、植物健康等领域的研究。

天车搭配使用的Plantarray系统

热点

保护细胞中PIF4的高表达减少了蒸腾作用。

保护细胞中HY5的表达增强了蒸腾作用。

保护细胞中HY5的表达升高可以逆转HXK1保护细胞活性所造成的低蒸腾作用。

摘要

全植物蒸腾作用受植物水力和气孔运动的控制，受内源和环境信号的调节，光在其中起主导作用。气孔孔径不断调整以适应光照强度和质量的变化，一方面确保光合作用的最佳CO2摄入，另一方面确保水分损失最小。光照和蒸腾作用之间的联系已经很好地确立，但关于保卫细胞如何感知这些信号来影响气孔导度的遗传知识仍然有限。在目前的研究中，我们评估了两个中心光响应转录因子的作用；bZIP家族转录因子延伸的下胚轴5（HY5）和基本螺旋环螺旋（BHLH）转录因子植物色素相互作用因子4（PIF4）。我们发现，PIF4在保卫细胞（GCPIF4）中的过度表达降低了蒸腾作用，并可以抑制PIF4突变体的高蒸腾作用。此外，我们发现GCHY5可以逆转由糖传感器HEXOKINASE1（HXK1，GCHXK）的保护细胞过度表达引起的低蒸腾作用，这是一种已建立的低蒸腾基因型。最后，我们认为GCHXK逆转GCHY5的低蒸腾作用需要其他组织中内源性HY5的自动激活。这些发现支持了气孔中光响应转录因子HY5和PIF4对蒸腾作用的持续昼夜调节，从而最终决定了整个植物的水分利用效率。

Guard cell activity of PIF4 and HY5 control transpiration

Highlights

Elevated expression of PIF4 in guard cells reduces transpiration.

Elevated expression of HY5 in guard cells enhances transpiration.

Elevated expression of HY5 in guard cells can reverse the low transpiration imposed by guard cell activity of HXK1.

Abstract

Whole-plant transpiration, controlled by plant hydraulics and stomatal movement, is regulated by endogenous and environmental signals, with the light playing a dominant role. Stomatal pore size continuously adjusts to changes in light intensity and quality to ensure optimal CO2 intake for photosynthesis on the one hand, together with minimal water loss on the other. The link between light and transpiration is well established, but the genetic knowledge of how guard cells perceive those signals to affect stomatal conductance is still somewhat limited. In the current study, we evalsuated the role of two central light-responsive transcription factors; a bZIP-family transcription factor ELONGATED HYPOCOTYL5 (HY5) and the basic helix-loop-helix (BHLH) transcription factor PHYTOCHROME INTERACTING FACTOR4 (PIF4), in the regulation of steady-state transpiration. We show that overexpression of PIF4 exclusively in guard cells (GCPIF4) decreases transpiration, and can restrain the high transpiration of the pif4 mutant. Expression of HY5 specifically in guard cells (GCHY5) had the opposite effect of enhancing transpiration rates of WT- Arabidopsis and tobacco plants and of the hy5 mutant in Arabidopsis. In addition, we show that GCHY5 can reverse the low transpiration caused by guard cell overexpression of the sugar sensor HEXOKINASE1 (HXK1, GCHXK), an established low transpiring genotype. Finally, we suggest that the GCHY5 reversion of low transpiration by GCHXK requires the auto-activation of the endogenous HY5 in other tissues. These findings support the existence of an ongoing diurnal regulation of transpiration by the light-responsive transcription factors HY5 and PIF4 in the stomata, which ultimately determine the whole-plant water use efficiency.

Keywords:Guard cells Stomata Transpiration HY5 PIF4 Water use efficiency