Down-Regulation of Cytokinin Receptor Gene SlHK2 Improves Plant Tolerance to Drought, Heat, and Combined Stresses in Tomato.

Naveed Mushtaq,Yi Li,Jing Ding,Junmiao Fan,Yong Wang

doi:10.3390/plants11020154

Abstract

Environmental stresses negatively affect the growth and development of plants. Several previous studies have elucidated the response mechanisms of plants to drought and heat applied separately; however, these two abiotic stresses often coincide in environmental conditions. The global climate change pattern has projected that combined drought and heat stresses will tend to increase in the near future. In this study, we down-regulated the expression of a cytokinin receptor gene SlHK2 using RNAi and investigated the role of this gene in regulating plant responses to individual drought, heat, and combined stresses (drought + heat) in tomato. Compared to the wild-type (WT), SlHK2 RNAi plants exhibited fewer stress symptoms in response to individual and combined stress treatments. The enhanced abiotic stress tolerance of SlHK2 RNAi plants can be associated with increased membrane stability, osmoprotectant accumulation, and antioxidant enzyme activities. Furthermore, photosynthesis machinery was also protected in SlHK2 RNAi plants. Collectively, our results show that down-regulation of the cytokinin receptor gene SlHK2, and consequently cytokinin signaling, can improve plant tolerance to drought, heat, and combined stress.

Highlights

IntroductionAbiotic stresses induced by environmental conditions may adversely limit plant growth and productivity [1,2]
Received: 4 November 2021Abiotic stresses induced by environmental conditions may adversely limit plant growth and productivity [1,2]
We found that the maintenance of cell membrane stability, photosynthesis machinery protection, accumulation of osmoprotectants, reduced reactive oxygen species (ROS) accumulation, increased antioxidant enzyme activities, up-regulation of antioxidant genes, and up-regulation of cuticle wax biosynthesis genes played roles in the abiotic stress tolerance of SlHK2 RNAi plants

Summary

Introduction

Abiotic stresses induced by environmental conditions may adversely limit plant growth and productivity [1,2]. Plants counter abiotic stresses with several changes in their morphological, biochemical, physiological, and molecular levels [3,4]. Various abiotic stresses naturally coincide in the field, where plants are exposed to multiple abiotic stresses. Among these stresses, heat and drought are significant constraints on global plant growth and food security [5,6]. As heat and drought stresses are involved in combination, the plant’s physiological responses were notable to be inferred from individual stress analysis. The combined stress reduces yield more than a single stress; the combination of drought and heat is perceived as the most severe challenge, negatively impacting plant growth and yield [1,8]

Results

Discussion

Conclusion