Characterization of the aquaporin gene family in Pinus massoniana and functional analysis of PmNIP2;1 involved in high-temperature and drought stress

Aquaporin (AQP) in plants can regulate the transport of water and various small solutes and play important roles in plant development and abiotic stress responses. The aquaporin gene family in Pinus massoniana has not yet been described. In this study, 30 PmAQP genes were identified in P . massoniana seedlings. Based on phylogenetic analysis, these genes were categorized into four groups: 12 plasma membrane intrinsic proteins ( PIPs ), 11 tonoplast intrinsic proteins ( TIPs ), 5 NOD26-like intrinsic proteins ( NIPs ), and 2 small basic intrinsic proteins ( SIPs ). Within each group, the conserved motifs, tertiary structures, and aromatic/arginine selectivity filter (ar/R) presented high similarity. Subcellular localization analysis in Nicotiana benthamiana epidermal cells revealed a diverse and broad array of PmPIPs with various subcellular locations. Expression profiling revealed that 14 PmAQPs in leaves presented specific expression patterns under high-temperature stress, drought stress and combined high-temperature and drought stress. These findings suggest that PmAQP family genes may be involved in the response to high-temperature, drought and the combined stress of high temperature and drought. The overexpression of PmNIP2;1 promoted the root development of transgenic tobacco and improved the tolerance of transgenic tobacco to high-temperature, drought and the combination of high-temperature and drought by regulating the expression of stress resistance genes and changes in physiological and biochemical substances in transgenic tobacco. This study provides a comprehensive transcriptome-wide analysis of the aquaporin gene family, shedding light on its potential roles in plant growth and stress responses.