Abscisic Acid Negatively Modulates Heat Tolerance in Rolled Leaf Rice by Increasing Leaf Temperature and Regulating Energy Homeostasis

Guangyan Li,Shaobing Peng,Caixia Zhang,Tingting Chen,Guangheng Zhang,Weimeng Fu,Guanfu Fu,Baohua Feng,Longxing Tao

doi:10.1186/s12284-020-00379-3

Abstract

BackgroundAbscisic acid (ABA) acts as a signaling hormone in plants against abiotic stress, but its function in energy homeostasis under heat stress is unclear.ResultsTwo rice genotypes, Nipponbare (wild-type, WT) with flat leaves and its mutant high temperature susceptibility (hts) plant with semi-rolled leaves, were subjected to heat stress. We found significantly higher tissue temperature, respiration rate, and ABA and H2O2 contents in leaves as well as a lower transpiration rate and stomatal conductance in hts than WT plants. Additionally, increased expression of HSP71.1 and HSP24.1 as well as greater increases in carbohydrate content, ATP, NAD (H), and dry matter weight, were detected in WT than hts plants under heat stress. More importantly, exogenous ABA significantly decreased heat tolerance of hts plants, but clearly enhanced heat resistance of WT plants. The increases in carbohydrates, ATP, NAD (H), and heat shock proteins in WT plants were enhanced by ABA under heat stress, whereas these increases were reduced in hts plants.ConclusionIt was concluded that ABA is a negative regulator of heat tolerance in hts plants with semi-rolled leaves by modulating energy homeostasis.

Highlights

Abscisic acid (ABA) acts as a signaling hormone in plants against abiotic stress, but its function in energy homeostasis under heat stress is unclear
Response of the Rice Plants to Different Temperatures To investigate the response of rice plants to different temperature stresses, the wild-type Nipponbare (WT) and hts plants were subjected to temperatures of 30 °C, 35 °C, and 40 °C for 72 h, and the plants were subjected to 45 °C heat stress for 24 h (Fig. 1a)
No marked differences were detected in Relative electrical conductance (REC) or chlorophyll content between the control and the 40 °C heat stressed WT plants, while a remarkable increase was found in hts plants under heat stress compared with the control (Fig. 1d and e)

Summary

Introduction

Abscisic acid (ABA) acts as a signaling hormone in plants against abiotic stress, but its function in energy homeostasis under heat stress is unclear. Abscisic acid (ABA) is an important phytohormone controlling many developmental and physiological processes under natural and stressed conditions (Verslues and Zhu 2007; Huang et al 2017). ABA accumulates in the developing embryo where it regulates seed development, seed maturation, and seed dormancy (Verslues and Zhu 2007). It acts as a signaling molecule to defend against biotic stress including pathogen infection (Mittler and Blumwald 2015; Kang et al 2017). ABA functions in the heat stress response in plants, but the underlying mechanism remains unclear

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