Functional Characterization of Cotton C-Repeat Binding Factor Genes Reveal Their Potential Role in Cold Stress Tolerance.

Jiangna Liu,Richard Odongo Magwanga,Xiaoyan Cai,Stephen Gaya Agong,Kunbo Wang,Yuhong Wang,Yuqing Hou,Yanchao Xu,Zhongli Zhou,Fang Liu,Tingting Wei,Joy Nyangasi Kirungu,Jie Zheng,Erick Okuto

doi:10.3389/fpls.2021.766130

Abstract

Low temperature is a common biological abiotic stress in major cotton-growing areas. Cold stress significantly affects the growth, yield, and yield quality of cotton. Therefore, it is important to develop more robust and cold stress-resilient cotton germplasms. In response to climate change and erratic weather conditions, plants have evolved various survival mechanisms, one of which involves the induction of various stress responsive transcript factors, of which the C-repeat-binding factors (CBFs) have a positive effect in enhancing plants response to cold stress. In this study, genomewide identification and functional characterization of the cotton CBFs were carried out. A total of 29, 28, 25, 21, 30, 26, and 15 proteins encoded by the CBF genes were identified in seven Gossypium species. A phylogenetic evaluation revealed seven clades, with Clades 1 and 6 being the largest. Moreover, the majority of the proteins encoded by the genes were predicted to be located within the nucleus, while some were distributed in other parts of the cell. Based on the transcriptome and RT-qPCR analysis, Gthu17439 (GthCBF4) was highly upregulated and was further validated through forward genetics. The Gthu17439 (GthCBF4) overexpressed plants exhibited significantly higher tolerance to cold stress, as evidenced by the higher germination rate, increased root growth, and high-induction levels of stress-responsive genes. Furthermore, the overexpressed plants under cold stress had significantly reduced oxidative damage due to a reduction in hydrogen peroxide (H2O2) production. Moreover, the overexpressed plants under cold stress had minimal cell damage compared to the wild types, as evidenced by the Trypan and 3,3′-Diaminobenzidine (DAB) staining effect. The results showed that the Gthu17439 (GthCBF4) could be playing a significant role in enhancing cold stress tolerance in cotton and can be further exploited in developing cotton germplasm with improved cold-stress tolerance.

Highlights

Cotton is a thermophilic crop and is more sensitive to low temperature (Hemantaranjan et al, 2014); China being the major cotton-growing country globally, the site specific regions within China, such as Xinjiang, is often affected by cold, which lasts for more than a half growing of cotton plants, which results in negative effects on plant growth and development (Rihan et al, 2017)
In the analysis of the physicochemical properties of the C-repeat-binding factors (CBFs) proteins, the results showed a great variation; for instance, the CBF proteins obtained from the G. herbaceum, their molecular weights (MW) ranged from 11.24188 to 39.02073 kDa; isoelectric value ranged from 5.26 to 10.27, while, in G. thurberi, the MW of the proteins encoded by the CBF genes ranged from 16.17923 to 45.59153 kDa; the pI ranged from 5.11 to 10.83
Cotton is an important economic crop, which supports the economies of several countries globally; it is the primary source of natural fiber critical raw material for the textile industries (Reddy and Yang, 2009); in the recent past, its global production has significantly shrunken due to climate change

Summary

Introduction

Cotton is a thermophilic crop and is more sensitive to low temperature (Hemantaranjan et al, 2014); China being the major cotton-growing country globally, the site specific regions within China, such as Xinjiang, is often affected by cold, which lasts for more than a half growing of cotton plants, which results in negative effects on plant growth and development (Rihan et al, 2017). Cold stress leads to inhibition of seed germination, reduction of plant growth, and reproduction, as well as a decrease in crop yield and quality (Körner, 2016). Many crops, such as rice (Oryza sativa), maize (Zea mays), tomato (Solanum lycopersicum), soybean (Glycine max), and cotton (Gossypium hirsutum), do lack the ability to adapt to environments with low temperature, highly adaptive to tropical or subtropical regions (Xiong et al, 2002; Wang et al, 2017; Kumar Verma et al, 2018). When plants are exposed to chilling conditions, the plants do mobilize the cold-response genes (COR), which activate

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Conclusion