Over-Expression of OsHOX24 Confers Enhanced Susceptibility to Abiotic Stresses in Transgenic Rice via Modulating Stress-Responsive Gene Expression.

Annapurna Bhattacharjee,Mukesh Jain,Raghvendra Sharma

doi:10.3389/fpls.2017.00628

Abstract

Homeobox transcription factors play critical roles in plant development and abiotic stress responses. In the present study, we raised rice transgenics over-expressing stress-responsive OsHOX24 gene (rice homeodomain-leucine zipper I sub-family member) and analyzed their response to various abiotic stresses at different stages of development. At the seed germination stage, rice transgenics over-expressing OsHOX24 exhibited enhanced sensitivity to abiotic stress conditions and abscisic acid as compared to wild-type (WT). OsHOX24 over-expression rice seedlings showed reduced root and shoot growth under salinity and desiccation stress (DS) conditions. Various physiological and phenotypic assays confirmed higher susceptibility of rice transgenics toward abiotic stresses as compared to WT at mature and reproductive stages of rice development too. Global gene expression profiling revealed differential regulation of several genes in the transgenic plants under control and DS conditions. Many of these differentially expressed genes were found to be involved in transcriptional regulatory activities, besides carbohydrate, nucleic acid and lipid metabolic processes and response to abiotic stress and hormones. Taken together, our findings highlighted the role of OsHOX24 in regulation of abiotic stress responses via modulating the expression of stress-responsive genes in rice.

Highlights

Extreme environmental perturbations, such as drought, cold, high salinity and temperature influence the growth, survival and productivity of plants
Over-expression of OsHOX24 resulted in significant alteration in the phenotype of rice transgenics at the reproductive stage (Supplementary Figure S2A)
We found that OsHOX24 rice transgenics possessed impaired ability of stomatal closure as compared to WT due to higher sensitivity to ABA, which suggested the role of OsHOX24 in modulating abiotic stress responses in rice

Summary

Introduction

Extreme environmental perturbations, such as drought, cold, high salinity and temperature influence the growth, survival and productivity of plants. The economically important cereal crops like rice are severely affected due to the adverse environmental onslaughts leading to heavy losses in yield. The transcript levels of various stress-responsive genes are altered in plants. Several transcription factors (TFs) are known to be prominently involved in abiotic stress responses. They are major components of transcriptional regulatory networks called regulons as they modulate the expression of several downstream target genes during abiotic stresses in plants (Nakashima et al, 2009; Urano et al, 2010; Todaka et al, 2015).

Methods

Results

Discussion

Conclusion