Overexpression of Plasma Membrane H+-ATPase in Guard Cells Enhances Light-Induced Stomatal Opening, Photosynthesis, and Plant Growth in Hybrid Aspen.

Shigeo Toh,Yuki Hayashi,Nobutaka Mitsuda,Yosuke Toda,Toru Taniguchi,Toshinori Kinoshita,Yin Wang,Naoki Takata,Eigo Ando,Soichiro Nagano

doi:10.3389/fpls.2021.766037

Abstract

Stomata in the plant epidermis open in response to light and regulate CO2 uptake for photosynthesis and transpiration for uptake of water and nutrients from roots. Light-induced stomatal opening is mediated by activation of the plasma membrane (PM) H+-ATPase in guard cells. Overexpression of PM H+-ATPase in guard cells promotes light-induced stomatal opening, enhancing photosynthesis and growth in Arabidopsis thaliana. In this study, transgenic hybrid aspens overexpressing Arabidopsis PM H+-ATPase (AHA2) in guard cells under the strong guard cell promoter Arabidopsis GC1 (AtGC1) showed enhanced light-induced stomatal opening, photosynthesis, and growth. First, we confirmed that AtGC1 induces GUS expression specifically in guard cells in hybrid aspens. Thus, we produced AtGC1::AHA2 transgenic hybrid aspens and confirmed expression of AHA2 in AtGC1::AHA2 transgenic plants. In addition, AtGC1::AHA2 transgenic plants showed a higher PM H+-ATPase protein level in guard cells. Analysis using a gas exchange system revealed that transpiration and the photosynthetic rate were significantly increased in AtGC1::AHA2 transgenic aspen plants. AtGC1::AHA2 transgenic plants showed a>20% higher stem elongation rate than the wild type (WT). Therefore, overexpression of PM H+-ATPase in guard cells promotes the growth of perennial woody plants.

Highlights

In an era of global climate change and food shortages, finding ways to improve the absorption of CO2 by land plants is becoming an increasingly important issue
Our results indicate that AtGC1::A. thaliana HA2 (AHA2) transgenic hybrid aspens had a higher stem elongation rate and greater biomass production than the wild type (WT), likely due to the enhanced stomatal opening and photosynthetic rate
plasma membrane (PM) H+-ATPases are highly conserved among plant species, and their gene numbers vary among plant species (e.g., 11 isoforms in A. thaliana, nine in Nicotiana plumbaginifolia, and 10 in O. sativa; Arango et al, 2003)

Summary

Introduction

In an era of global climate change and food shortages, finding ways to improve the absorption of CO2 by land plants is becoming an increasingly important issue. Stomatal pores in the epidermis are surrounded by two guard cells and are important for capturing CO2. Enhancement of gas exchange by stomatal opening is essential for photosynthesis and transpiration (Shimazaki et al, 2007). Stomatal transpiration limits photosynthesis in rice (Kusumi et al, 2012). Increasing the stomatal opening and transpiration could enhance photosynthesis and plant growth. Transgenic Arabidopsis thaliana (Arabidopsis) overexpressing plasma membrane (PM) H+-ATPase, a key enzyme for stomatal opening, in guard cells promotes light-induced stomatal aperture opening, photosynthetic activity, and plant growth (Wang et al, 2014). The overexpression of PM H+-ATPase in rice increases stomatal opening, nutrient uptake, and photosynthesis, enhancing grain yield in paddy fields (Zhang et al, 2021). We propose designating plants overexpressing PM H+-ATPase as Promotion and Upregulation of plasma Membrane ProtonATPase (PUMP) plants

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