Elevation of GhDREB1B transcription by a copy number variant significantly improves chilling tolerance in cotton

The elevation of transcript levels of GhDREB1B causes the accumulation of osmoregulants and mitigation of reactive oxygen species, which contributes to the enhanced resistance to chilling stress in AiSheng98 cotton. Low temperature is one of the key environmental stresses that impairs cotton growth and restricts fiber productivity. Dehydration responsive element binding (DREB) transcription factors play an important role in cold response in plants by modulating the transcription level of cold-responsive genes to protect the plants from low-temperature stress. Here, we showed that GhDREB1B, a copy number variant in the AiSheng98 (AS98) cotton mutant, significantly improved chilling tolerance in cotton seedlings, while silencing of GhDREB1B made transgenic cotton sensitive to chilling stress in AS98 cotton compared with control plants. Elevated GhDREB1B transcript level activated the expression of major cold-responsive genes. Genome-wide expression profiling by RNA sequencing revealed the upregulation of genes related to fatty acids, lipid proteins, osmoprotection, and anti-oxidative enzymes in AiSheng98. Excessive accumulation of malondialdehyde (MDA) and higher ion leakage rates occurred in wild-type LFH10 plants when compared to those of Aisheng98 during chilling stress, signifying lower chilling tolerance in the wild-type than in Aisheng98. Furthermore, the Aisheng98 mutant under chilling stress accumulated higher levels of free proline and soluble sugar than LFH10 accumulated. These results suggest that GhDREB1B is a positive regulator and its variant can alter the expression patterns of major low-temperature stress-related genes and enhance chilling tolerance in cotton.