Genome-wide identification of CDPK gene family in Paspalum vaginatum and characterization of PvCDPK5 associated with salt tolerance

Abstract

Turfgrass species commonly used for lawns, sports fields, and urban green spaces frequently encounter salt exposure. Under conditions of salt stress, the quality of the turfgrass diminishes, leading to a loss of economic value and a reduction in its ability to serve recreational and functional purposes. Salt stress responses are critical for the survival and functionality of turfgrass in saline environments. Paspalum vaginatum (seashore paspalum), a stress-tolerant turfgrass widely used in lawns and golf courses, is an ideal model for studying plant stress adaptation. The calcium-dependent protein kinases (CDPKs) family, key regulators of plant growth, development, and stress signaling, remains uncharacterized in this species. Using evolutionarily conserved CDPK protein sequences from Arabidopsis thaliana, Oryza sativa, and Zea mays as references, we performed a genome-wide identification of CDPKs in P. vaginatum and ultimately identified 30 candidate PvCDPK genes. We analyzed conserved domains, gene structures, chromosomal distribution, and phylogenetic relationships of PvCDPKs. Promoter cis-element analysis identified phytohormone-responsive, stress-responsive, and growth/development-related motifs. Quantitative reverse transcription PCR (qRT-PCR) of PvCDPKs demonstrated tissue-specific expression profiles and differential regulation under salt stress, drought stress, cold stress, and ABA treatment conditions. Overexpression of PvCDPK5 in A. thaliana showed that the transgenic plants exhibited significantly enhanced salt tolerance, accompanied by reduced reactive oxygen species (ROS) accumulation, decreased malondialdehyde (MDA) content, increased activities of antioxidant enzymes, and improved Na⁺/K⁺ balance. Collectively, these results suggest that PvCDPK5 regulates plant salt tolerance by mediating the alleviation of oxidative stress and maintaining ion homeostasis. Furthermore, insights into turfgrass salt adaptation can inform breeding strategies for other salt-sensitive crops, thereby enhancing agricultural productivity in salinized soils.