Characterization of Phytochrome-Interacting Factor Genes in Pepper and Functional Analysis of CaPIF8 in Cold and Salt Stress

Youxin Yang; Yelan Guang; Feng Wang; Yue Chen; Wenting Yang; Xufeng Xiao; Sha Luo; Yong Zhou

doi:10.3389/fpls.2021.746517

Characterization of Phytochrome-Interacting Factor Genes in Pepper and Functional Analysis of CaPIF8 in Cold and Salt Stress

Front Plant Sci. 2021 Oct 25:12:746517. doi: 10.3389/fpls.2021.746517. eCollection 2021.

Authors

Youxin Yang¹, Yelan Guang¹, Feng Wang², Yue Chen¹, Wenting Yang³, Xufeng Xiao¹, Sha Luo¹, Yong Zhou^{3

4}

Affiliations

¹ Jiangxi Key Laboratory for Postharvest Technology and Nondestructive Testing of Fruits and Vegetables, Collaborative Innovation Center of Post-Harvest Key Technology and Quality Safety of Fruits and Vegetables, College of Agronomy, Jiangxi Agricultural University, Nanchang, China.
² College of Horticulture, Shenyang Agricultural University, Shenyang, China.
³ Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, Jiangxi Agricultural University, Nanchang, China.
⁴ College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, China.

Abstract

As a subfamily of basic helix-loop-helix (bHLH) transcription factors, phytochrome-interacting factors (PIFs) participate in regulating light-dependent growth and development of plants. However, limited information is available about PIFs in pepper. In the present study, we identified six pepper PIF genes using bioinformatics-based methods. Phylogenetic analysis revealed that the PIFs from pepper and some other plants could be divided into three distinct groups. Motif analysis revealed the presence of many conserved motifs, which is consistent with the classification of PIF proteins. Gene structure analysis suggested that the CaPIF genes have five to seven introns, exhibiting a relatively more stable intron number than other plants such as rice, maize, and tomato. Expression analysis showed that CaPIF8 was up-regulated by cold and salt treatments. CaPIF8-silenced pepper plants obtained by virus-induced gene silencing (VIGS) exhibited higher sensitivity to cold and salt stress, with an obvious increase in relative electrolyte leakage (REL) and variations in the expression of stress-related genes. Further stress tolerance assays revealed that CaPIF8 plays different regulatory roles in cold and salt stress response by promoting the expression of the CBF1 gene and ABA biosynthesis genes, respectively. Our results reveal the key roles of CaPIF8 in cold and salt tolerance of pepper, and lay a solid foundation for clarifying the biological roles of PIFs in pepper and other plants.

Keywords: cold stress; expression profile; pepper; phytochrome-interacting factor (PIF); salt stress.