Wheat F-box Protein TaFBA1 Positively Regulates Plant Drought Tolerance but Negatively Regulates Stomatal Closure.

Jie An,Qinxue Li,Yong Wang,Zhongxian Zhao,Junjiao Yang,Yunzhen Wu,Guangqiang Zhang,Wei Wang

doi:10.3389/fpls.2019.01242

Abstract

The phytohormone abscisic acid (ABA) regulates plant growth and development, as well as responses to various stresses, such as salt and drought. The wheat TaFBA1 gene, which encodes an F-box protein, was previously identified in our laboratory by homologous cloning. We previously found that TaFBA1 expression was induced by ABA and drought stress. In this study, wild-type (WT), TaFBA1 over-expressing (OEs), TaFBA1 homologous gene mutants, and TaFBA1 recovery (Rs) Arabidopsis plants were used. We found that the germination rate, the cotyledon greening rate, the root length, and the photosynthetic performance of TaFBA1 OE plants were better than those of WT under drought and ABA conditions, but mutant plants showed the opposite trend, and overexpression of TaFBA1 in mutants can recover their phenotype. In addition, TaFBA1 was found to be a negative regulator of ABA-induced stoma movement; mRNA transcription of certain ABA signaling-related genes was lower in TaFBA1 OE plants than in WT plants following ABA treatment. Further, we found that TaFBA1 can interact with RCAR1 (an ABA receptor) and ABI5. BiFC assay showed that TaFBA1 may interact with RCAR1 in the plasma membrane. In addition, accumulation of ROS and MDA in TaFBA1 OE plants was lower than that in the WT plants after ABA and drought treatments. Based on these results, we suggest that TaFBA1-regulated ABA insensitivity may be dependent on regulating ABA-mediated gene expression through interacting with RCAR1 and ABI5. Increased antioxidant competence and decreased ROS accumulation may be an important mechanism that underlies improved drought tolerance in TaFBA1 OE plants.

Highlights

Drought stress is one of the most common environmental stresses in crops and affects the growth and development of plants
To study the functions of wheat TaFBA1 in drought tolerance and stoma movement, the transgenic Arabidopsis plants with overexpressed TaFBA1 (OEs), OE4, OE5, and OE6 were used in this experiment (Figures 1A, B and Figure S1)
It was found that AtFBW2 and TaFBA1 have similar gene expression patterns when responding to salt stress (Zhao et al, 2017)

Summary

Introduction

Drought stress is one of the most common environmental stresses in crops and affects the growth and development of plants. To maintain their water balance, plants usually close their stomata to reduce transpiration. This limits CO2 entry, which is detrimental to photosynthesis (Franks and Beerling, 2009). Stomatal closure reduces CO2 absorption under drought conditions, resulting in decreased dark reaction rate of photosynthesis, this is closely associated with cell damage caused by excessive accumulation of reactive oxygen species (ROS) in plants (Posch and Bennett, 2009; Juvany et al, 2014). By controlling the flow of water and CO2, stomata can allow plants to adapt to stress

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