Genome-wide identification of aquaporin family in Camellia oleifera and their response characteristics to drought stress.

Aquaporins (AQPs) facilitate transmembrane water transport and are essential for plant growth, development, and stress adaptation. Camellia oleifera is an important woody edible oil tree. Drought stress frequently occurs during the rapid fruit expansion and maturation stages, and AQPs might mediate its drought response. However, the diversity, molecular characteristics and biological functions of AQPs in C. oleifera remain largely uncharacterized. Here, 166 CoAQPs were identified and classified into five subfamilies based on phylogenetic analysis. They were mainly localized to the plasma membrane and vacuole. Members within the same subfamily shared conserved gene structures and motif compositions. Segmental duplication was the main driving force for CoAQPs expansion. The promoter region of CoAQPs contained abundant cis-acting elements associated with light response, phytohormone response, stress response, and plant growth and development. Tissue-specific expression analysis revealed that 50 CoAQPs were highly expressed in leaves, whereas 27 CoAQPs showed differential expression in developing seeds. Drought stress induced significant physiological and biochemical responses in leaves and fruits of C. oleifera. Transcriptome data and real-time quantitative PCR analyses indicated CoAQPs extensively participated in drought response. This study will lay a theoretical foundation for exploring water metabolism mechanisms and screening gene resources for stress tolerance and quality improvement in C. oleifera.