Genome-wide identification and stress response expression analysis of the heavy metal-associated isoprenylated plant protein gene family in tobacco (Nicotiana tabacum L.)

Heavy metal-associated isoprenylated plant proteins (HIPPs) are a class of metallochaperone proteins crucial for plant growth, development, and stress responses. However, a systematic investigation of the tobacco HIPP family has not been conducted. In this study, we identified 68 NtHIPP genes, all of which had conserved heavy metal-associated structural domains and the C-terminal isoprenoid motif CaaX. Phylogenetic analyses categorized NtHIPP genes into five clades, with 37 NtHIPP genes unevenly distributed across 18 tobacco chromosomes. Collinearity relationship analysis revealed that segmental duplication was a major factor in the evolution of these genes, and they exhibit a closer evolutionary relationship to dicots (Arabidopsis thaliana and Solanum lycopersicum) compared to monocots (Triticum aestivum and Oryza sativa). RNA-seq data indicated NtHIPP genes had different expression profiles in the shoot apex, shoot, and root, and some genes showing differential expression in response to drought, cold, cadmium stress, and Ralstonia solanacearum infection. Eight NtHIPP genes, as identified via reverse transcription-quantitative Polymerase Chain Reaction (RT-qPCR), exhibited positive or negative responses to various environmental stimuli under abiotic stress and hormone treatments. This study elucidates the relationship between NtHIPP genes and plant stress responses, providing new candidates for exploring stress-resistant germplasm resources in tobacco.