Genome wide identification of the trihelix transcription factors and overexpression of Gh_A05G2067 (GT-2), a novel gene contributing to increased drought and salt stresses tolerance in cotton.

Richard O Magwanga,Baohong Zhang,Pu Lu,Yuqing Hou,Qi Dong,Stephen G Agong,Fang Liu,Yanchao Xu,Kunbo Wang,Regina Nyunja,Xiu Yang,Xiaoyan Cai,Xingxing Wang,Zhongli Zhou,Joy N Kirungu,Jinping Hua

doi:10.1111/ppl.12920

Abstract

We identified 102, 51 and 51 proteins encoded by the trihelix genes in Gossypium hirsutum, Gossypium arboreum and Gossypium raimondii, respectively. RNA sequence data and real‐time quantitative polymerase chain reaction analysis showed that Gh_A05G2067 (GT‐2) was highly upregulated under drought and salt stress conditions. Transient expression of GT‐2‐green fluorescent protein fusion protein in protoplast showed that GT‐2 was localized in the nucleus. The overexpression of GT‐2 conferred an enhanced drought tolerance to cotton, with lower malondialdehyde, hydrogen peroxide contents and higher reactive oxygen scavenging enzyme activities. Moreover, chlorophyll content, relative leaf water content (RLWC), excised leaf water loss (ELWL) and cell membrane stability (CMS) were relatively stable in the GT‐2‐overexpressed lines compared to wild‐type (WT). Similarly, stress‐responsive genes RD29A, SOS1, ABF4 and CBL1 were highly upregulated in the GT‐2‐overexpressed lines but were significantly downregulated in WT. In addition, the GT‐2‐silenced cotton plants exhibited a high level of oxidation injury, due to high levels of oxidant enzymes, in addition to negative effects on CMS, ELWL, RLWC and chlorophyll content. These results mark the foundation for future exploration of the trihelix genes in cotton, with an aim of developing more resilient, versatile and highly tolerant cotton genotypes.

Highlights

Abiotic stress factors cause massive losses in various agricultural crops (Rejeb et al 2014)
We identified a total of 204 putative proteins encoded by TH genes among the three cotton species, with 102, 51 and 51 proteins in G. hirsutum (AD)1, G. raimondii (D5) and G. arboreum (A2), respectively
The majority of the late embryogenesis abundant (LEA) proteins grand average of hydropathy (GRAVY) values were found to be less than zero, an indication that the LEA proteins are hydrophilic in nature with profound roles in enhancing drought stress tolerance in cotton (Tunnacliffe and Wise 2007, Sasaki et al 2014, Li et al 2018)

Summary

Introduction

Abiotic stress factors cause massive losses in various agricultural crops (Rejeb et al 2014). Abbreviations – CAT, Catalase; CMS, Cell membrane stability; H2O2, Hydrogen peroxide; MDA, Malondialdehyde; POD, Peroxidase; RLWC, Relative leaf water content; SLW, Saturated leaf weight; SLW, Saturated leaf weight; SOD, Superoxide dismutase; VIGS, Virus-induced gene silencing. Bear the full effect of any abiotic stress due to their sessile nature When abiotic stresses such as drought, salinity, heat, cold among others set in, the plant’s internal equilibrium changes, affecting all the biological and physiological activities within the plant (Mott and Parkhurst 1991, Aasamaa and Sõber 2011). The various responses of plants are mainly regulated at the transcriptome levels; plants have evolved various stress-responsive genes enabling them to tolerate the adverse effects caused by the various stress factors

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Conclusion