Freezing transcriptome analysis showed that GhZAT10 regulates freezing tolerance through a partially CBF-dependent pathway in upland cotton (Gossypium hirsutum L.)

Abstract

Cotton is an important economic crop worldwide, which is mainly distributed in the tropics and subtropics; therefore, it is highly sensitive to low temperatures. ZAT and CBF play important roles in plant growth and stress responses. However, few studies have investigated the role of these genes in freezing tolerance of cotton, and the interaction between these two remains unclear. In this study, KN27–3 cotton with strong freezing tolerance was selected from 17 cotton varieties. RNA-sequencing analysis showed that KN27–3 cotton presented 6747 differentially expressed genes (DEGs), which were mostly upregulated at the early time points after the treatments. Weighted gene co-expression network analysis and Gene Ontology enrichment analysis showed that various DEGs were involved in plant abiotic stress resistance, including SRK2I, ELF3, WRKY70, and TPS6. Moreover, 31 early upregulated transcription factors, including CBF and ZAT, were identified after 15 min of freezing treatment. Such significant upregulation at the early stage suggested that GhCBF4 (Gh_A12G2357) and GhZAT10 (Gh_D05G2011) play important roles in cotton freezing stress. Virus-induced gene silencing indicated that GhCBF4- and GhZAT10-silenced plants exhibit significant freezing-sensitive phenotypes. Biofilm interferometry and dual luciferase experiments showed that GhCBF4 regulated transcription by directly binding to a CRT/DRE motif within the GhZAT10 promoter. In summary, GhZAT10 and GhCBF4 regulated plant freezing tolerance, and GhZAT10 expression was at least partially regulated by CBF. These findings expand our current understanding of the mechanisms underlying GhZAT10- and GhCBF4-mediated freezing stress reactions in cotton, thereby establishing a foundation for further research on the molecular mechanisms underlying cotton freezing tolerance.