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

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.

Isolation and Functional Analysis of VvWRKY28, a Vitis vinifera WRKY Transcription Factor Gene, with Functions in Tolerance to Cold and Salt Stress in Transgenic Arabidopsis thaliana

“…Thus, the adaptability of plants to salt stress was improved. The expression levels of these genes were generally consistent with previous studies [ 54 , 55 ]. These results suggested that plants can not only improve their tolerance to low temperature by combining with cis-acting elements of downstream target genes, but also regulate the expression of downstream genes related to salt stress through ABA-dependent and ABA-independent pathways, as well as ROS and SOS pathways, so as to make plants more adapted to high salt environment.…”

Transcriptome and Metabolome Analyses Reveal Molecular Responses of Two Pepper (Capsicum annuum L.) Cultivars to Cold Stress

“…Moreover, PIFs (phytochrome-interacting factors), a subfamily of bHLH TFs, mainly participate in the photomorphogenic development, and several members also as thermo-sensors, involved in cold response ( Jiang et al, 2020 ; Zheng et al, 2020 ). Yang et al (2021) found that six PIF members were existed in pepper, including CaPIF1 , CaPIF3 , CaPIF4 , CaPIF7a , CaPIF7b and CaPIF8 , among them, CaPIF8 was induced under cold stress. Here, a new gene (Newgene_7768) encoding PIF3 was identified and was downregulated under cold stress ( Supplementary Table 14 ), which was consistent with the present results on PIF3 ( Jiang et al, 2017 ).…”

Isolation and Functional Analysis of MbCBF2, a Malus baccata (L.) Borkh CBF Transcription Factor Gene, with Functions in Tolerance to Cold and Salt Stress in Transgenic Arabidopsis thaliana

“…The expression of the ABA signal transduction-related gene AtSNRK2.4 , the ABA synthesis gene AtNCED3 and gene PIF1/4 regulating ABA synthesis in MbCBF2 transgenic A. thaliana was further explored. From the analysis results of the expression changes of the downstream genes of six important CBF TFs ( Figure 9 ), AtCAT1 ( A. thaliana , NM_118231.4) [ 50 ], AtP5CS ( A. thaliana , D32138.1) [ 51 ], AtNCED3 ( A. thaliana , NM_112304.3) [ 50 ], AtPIF1 ( A. thaliana , CR457097.1) [ 52 ], AtPIF4 ( A. thaliana , NM_001337007.1) [ 52 ] and AtSnRK2.4 ( A. thaliana , AT1G10940) [ 53 ], it can be seen that in a normal growth environment, the expression of these genes in all A. thaliana strains was almost the same. ( Figure 9 ).…”