AmChi7, an AmWRKY59 - Activated chitinase, was involved in the adaption to winter climate in Ammopiptanthusmongolicus.

Chitinases are enzymes that hydrolyze β-1,4-glycosidic bonds in chitin. Previous studies have shown that several chitinases accumulated significantly in A. mongolicus, suggesting that chitinases might participate in the adaptation to winter climate in Ammopiptanthus mongolicus. Here, we analyzed the evolution and expression patterns of the chitinase gene family in A. mongolicus and investigated the function and regulatory mechanisms of the AmChi7 gene in response to abiotic stress. The chitinase gene family in A. mongolicus comprises 27 members, many of which arose through formed by tandem and segmental duplication. Several chitinase genes, including AmChi7 gene, were significantly upregulated in winter. Overexpression of AmChi7 gene enhanced the tolerance of yeast to freeze-thaw cycle and osmotic stress, and enhanced the tolerance of transgenic Arabidopsis to low-temperature and drought stress. Furthermore, AmWRKY59, a MeJA-induced transcription factor, bound to the W box element in the AmChi7 gene promoter, activating its expression in winter. It is speculated that chitinase AmChi7 accumulation in winter enhances adaptation to temperate winter climates in A. mongolicus. This study expands our understanding of the biological functions of chitinases and provides insights into the molecular mechanisms underlying winter climate adaptation in A. mongolicus.