This invention provides an
expression vector pHH40 and its application in the construction of engineered *C. truncatula* strains, belonging to the field of microbial
engineering technology. pHH40, as an
expression vector, can significantly improve the success rate of exogenous
gene expression in *C. truncatula*. Furthermore, we used pHH40 to introduce the
heat shock protein encoding
gene lphsp into *C. truncatula*, and the resulting engineered *C. truncatula* strains can tolerate
ethanol concentrations up to 14%, and can more quickly initiate and complete malolactic (MLF)
fermentation in
wine production, shortening the
wine production cycle.