Regulation mechanism of HIPPs in response to heavy metal stress in plants

Heavy-metal-associated isoprenylated plant proteins (HIPPs) are characteristic proteins of vascular plants that contain two kinds of conserved structures, including heavy-metal-associated (HMA) domains and C-terminal isoprenylation sites (CaaX motifs). HIPPs play essential roles in plant responses to biotic and abiotic stresses. In this review, we analyzed the structural characteristics of HIPPs, and their evolutionary relationships, together with their classification characteristics for different species, and explored the subcellular locations of HIPPs and the expression patterns of HIPP genes under different heavy metal stresses. We also explored the functions and regulatory mechanisms of different HIPPs in response to heavy metal stress in Arabidopsis thaliana, Oryza sativa, and other species. Furthermore, we reviewed the relationship between the structural classifications of HIPPs and their responses to heavy metal stress in order to provide a theoretical basis for the functional identification and evaluation of the mechanism of HIPPs in other species in response to heavy metal stresses. Studying the stress resistance of grass is of great significance for improving the ecological environment. It is important to explore and identify the function of grass HIPPs, which will help to unveil the internal regulation network of grass responses to stress.