Genome-wide identification of pepper (Capsicum annuum L.) AAT gene family and expression analysis under salt stress

Background The AAT gene is a widely present and highly important amino transferase in organisms, connecting energy metabolism and nitrogen metabolism. Its role in the response of other plants to salt stress has been studied, but it is not yet clear in peppers. Results This study identified a total of 22 CazAAT genes from pepper varieties " Zunla-1 ". According to subcellular localization predictions, 18 CaAAT genes are distributed in cytoplasmic solutes, 2 in mitochondria, 1 in chloroplasts, and the remaining 1 gene potentially localize to both mitochondria and chloroplasts. Phylogenetic analysis indicates that CazAAT13 belongs to subfamily IV, alongside the salt stress-relieving AAT genes from Aeluropus lagopoides (Poaceae) and Dendrobium officinale . Under salt stress treatment, the expression levels of CazAAT11 and CazAAT13 were significantly upregulated. After exogenous Asp application, the expression of CazAAT11 was further enhanced, whereas the upregulation of CazAAT13 was reduced. These findings suggest that CazAAT11 and CazAAT13 may alleviate salt stress by regulating Asp metabolism. Furthermore, co-expression analysis suggests that regulating carbon and nitrogen metabolism could be another critical pathway through which CazAAT11 and CazAAT13 alleviate salt stress. Conclusions This study systematically analyzes the CaAAT gene family, providing preliminary insights for further research on pepper's response to salt stress.