Genome-wide identification of bHLH gene family and screening of candidate gene in response to salt stress in kiwifruit

As the second largest family of transcription factors in plants, bHLH is widely involved in the growth and development of organisms and their response to stress. In the past, there was no systematic division of this gene family in kiwifruit. In this study, we identified 206 AcbHLH genes, divided into 22 subfamilies, and analyzed chromosomal localization, physicochemical properties, conserved domains, and intron/exon composition. In addition, the repeat events of the AcbHLH gene in kiwifruit and the evolutionary relationship with Arabidopsis thaliana and Oryza sativa were further analyzed. We analyzed the expression levels of the AcbHLH genes under biotic and abiotic stresses (heat, low temperature, drought, and Bacillus anthracis infection). In addition, we also investigated the biological function of AcbHLH146 under salt stress using a VIGS-mediated gene silencing method. In the AcbHLH146-VIGS line, the content of H2O2 and O2- was lower and the damage was less. SOD, POD, and CAT enzyme activities are higher. These results suggest that AcbHLH146 may play a negative moderating role in the response of kiwifruit to salt stress. Our findings provide new insights into the potential role of AcbHLH146 under abiotic stress, and provide a theoretical basis for the molecular mechanism of Kiwifruit adaptation to salt stress.