The sea-island cotton GbTCP4 transcription factor positively regulates drought and salt stress responses.

TCP transcription factors play important regulatory roles in plant growth and development; however, their function in response to salt and drought stress in sea-island cotton (Gossypium barbadense) is unknown. Here, GbTCP4 expression was induced by abscisic acid (ABA), drought, and NaCl treatments. Under drought stress, compared to wild-type (WT) Arabidopsis , transgenic GbTCP4 -overexpressing Arabidopsis showed increased seed germination rate, root length and survival rate; additionally, it was ABA-insensitive at the germination stage but ABA-sensitive at the seedling stage, showing reduced stomatal opening and ABA enrichment. Under salt stress, compared to WT Arabidopsis , transgenic GbTCP4- overexpressing Arabidopsis showed greater root length, survival rate, and SPAD value and lower malondialdehyde (MDA) content. Conversely, under drought or salt stress, virus-induced gene-silenced GbTCP4 cotton showed decreased root length, area and volume and increased MDA content and sensitivity to drought and salt stress compared with control cotton. RNA-seq and quantitative real-time PCR analyses showed that GbTCP4 affected the transcription levels of genes across multiple abiotic stress-related metabolic pathways. Furthermore, GbTCP4 activated the transcription of GbUVR8 and GbbHLH130 by binding to their promoters. These results suggest that GbTCP4 positively regulates drought and salt stress responses and is a suitable candidate gene for improving plant drought and salt tolerance. • The sea-island cotton class II TCP gene GbTCP4 is induced by drought, salt, and ABA treatments. • Overexpression of GbTCP4 in Arabidopsis and silencing of GbTCP4 in cotton indicated that GbTCP4 is a positive regulator of drought and salt stress. • GbTCP4 regulates abiotic stress responses in an ABA-dependent manner. • The GbTCP4 transcription factor can affect the expression of key genes in multiple stress-related metabolic pathways. [ABSTRACT FROM AUTHOR]