Populus euphratica Apyrases Increase Drought Tolerance by Modulating Stomatal Aperture in Arabidopsis.

Yanli Zhang,Rui Zhao,Yinan Zhang,Nan Zhao,Xiaojing Liu,Huilong Zhang,Huilong Zhang,Jinke Li,Yuanling Sun,Xiaoyang Zhou,Shurong Deng,Jun Yao,Jiayin Deng,Shaoliang Chen

doi:10.3390/ijms22189892

Abstract

Stomatal regulation is crucial to reduce water consumption under drought conditions. Extracellular ATP (eATP) serves as a signaling agent in stomatal regulation; however, it is less known whether the eATP mediation of stomatal aperture is linked to apyrases (APYs), the principal enzymes that control the concentration of eATP. To clarify the role of APYs in stomatal control, PeAPY1 and PeAPY2 were isolated from Populus euphratica and transferred into Arabidopsis. Compared with the wild-type Arabidopsis and loss-of-function mutants (Atapy1 and Atapy2), PeAPY1- and PeAPY2-transgenic plants decreased stomatal aperture under mannitol treatment (200 mM, 2 h) and reduced water loss during air exposure (90 min). The role of apyrase in stomatal regulation resulted from its control in eATP-regulated stomatal movements and increased stomatal sensitivity to ABA. The bi-phasic dose-responses to applied nucleotides, i.e., the low ATP (0.3–1.0 mM)-promoted opening and high ATP (>2.0 mM)-promoted closure, were both restricted by P. euphratica apyrases. It is noteworthy that eATP at a low concentration (0.3 mM) counteracted ABA action in the regulation of stomatal aperture, while overexpression of PeAPY1 or PeAPY2 effectively diminished eATP promotion in opening, and consequently enhanced ABA action in closure. We postulate a speculative model of apyrase signaling in eATP- and ABA-regulated stomatal movements under drought.

Highlights

Under global climate change, drought is becoming more and more frequent and longer lasting worldwide [1,2,3,4]
PeAPY1 and PeAPY2 enhanced the Abscisic acid (ABA) action in stomatal control, including promoting closure in light and inhibiting opening of dark-adapted stomata transferred to light
After exposure to an osmotic stress caused by 200 mM mannitol (2 h), PeAPY1- and PeAPY2-transgenic plants showed typical lower stomatal aperture compared with WT and mutants under light conditions, including continuous light and dark-adapted leaves transferred to light (Figure 1B,C)

Summary

Introduction

Drought is becoming more and more frequent and longer lasting worldwide [1,2,3,4]. Genetic engineering is an effective strategy for increasing drought resistance in herbaceous and woody species [3,4]. The conserved signaling pathway attributed to stomatal movement can be a suitable target for genetic engineering since stomatal regulation is crucial to reduce water consumption when root water uptake is restrained [4,5,6,7,8,9]. Accumulating evidence has shown that eATP regulates stomatal aperture in Arabidopsis thaliana and Vicia faba [19,20,21,22]. It can be inferred that eATP has a potential role in mediating water status through regulation of stomatal aperture under drought conditions.

Methods

Results

Discussion

Conclusion