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Aquaporins are channel proteins that facilitate the transmembrane transport of water and other small neutral molecules, thereby playing vital roles in maintaining water and nutrition homeostasis in the life activities of all organisms. Canavalia rosea, a seashore and mangrove-accompanied halophyte with strong adaptability to adversity in tropical and subtropical regions, is a good model for studying the molecular mechanisms underlying extreme saline-alkaline and drought stress tolerance in leguminous plants. In this study, a PIP2 gene (CrPIP2, 3) was cloned from C. rosea, and its expression patterns and physiological roles in yeast and Arabidopsis thaliana heterologous expression systems under high salt-alkali and high osmotic stress conditions were examined. The expression of CrPIP2, 3 at the transcriptional level in C. rosea was affected by high salinity and alkali, high osmotic stress, and abscisic acid treatment. In yeast, the expression of CrPIP2, 3 enhanced salt/osmotic and oxidative sensitivity under high salt/osmotic and H2O2 stress. The overexpression of CrPIP2, 3 in A. thaliana could enhance the survival and recovery of transgenic plants under drought stress, and the seed germination and seedling growth of the CrPIP2, 3 OX (over-expression) lines showed slightly stronger tolerance to high salt/alkali than the wild-type. The transgenic plants also showed a higher response level to high-salinity and dehydration than the wild-type, mostly based on the up-regulated expression of salt/dehydration marker genes in A. thaliana plants. The reactive oxygen species (ROS) staining results indicated that the transgenic lines did not possess stronger ROS scavenging ability and stress tolerance than the wild-type under multiple stresses. The results confirmed that CrPIP2, 3 is involved in the response of C. rosea to salt and drought, and primarily acts by mediating water homeostasis rather than by acting as an ROS transporter, thereby influencing physiological processes under various abiotic stresses in plants.

Additional file 1: Figure S1. The structural features of the CrAQPs. a CrNIPs. b CrPIPs. c CrTIPs. d CrXIPs. e CrSIPs.

Additional file 9: Table S3. The categories of cis-acting elements identified in the CrAQPs’ promoter regions.

Additional file 7: Table S1. The obtained CrAQPs’ nucleotide and protein sequences information in this study.

Additional file 5: Figure S5. Salt and alkaline stress analyses of the transgenic plants with CrPIP1;5’s overexpression based on the growth of adult Arabidopsis. a Leaf phenotypes of the transgenic Arabidopsis OX lines and WT plants under 200 mM NaCl stress for 7 days. b Leaf phenotypes of the transgenic Arabidopsis OX lines and WT plants under 100 mM NaHCO3 (pH 8.2) stress for 4 days.

Additional file 4: Figure S4. Salt, salt-alkaline, and high osmotic stress analyses of the transgenic plants with CrPIP1;5’s overexpression based on seedling root lengths. Four-day-old seedlings were transplanted into MS medium containing NaCl, NaCl plus NaHCO3 (pH 8.2) or mannitol and then grown for 7 d before measuring the root length. a Photographs of the transgenic lines (CrPIP1;5OX 1#, OX 5#, and OX 10#) and WT seedlings on MS medium or MS medium with NaCl, NaCl plus NaHCO3 (pH 8.2), or mannitol; b‒d The seedling root lengths (mm) in WT and the transgenic lines under NaCl (b), NaCl plus NaHCO3 (pH 8.2) (c), or mannitol (d) stresses after 7 d. Error bars indicate the SD based on over three replicates (n ≥ 3). Asterisks indicate significant differences from the control (Student’ s t-test P values, * p < 0.05 and ** p < 0.01).

Additional file 6: Figure S6. Subcellular localization of the CrPIP1;5 protein. Arabidopsis roots expressing 35S:GFP-CrPIP1;5 fusion proteins (upper two lines) and 35S:GFP (lower line) were observed under a laser scanning confocal microscope.

Additional file 8: Table S2. Primers’ information used in this study.

Additional file 2: Figure S2. The overexpression analyses of CrPIP1;5 in the three transgenic Arabidopsis lines (OX 1#, OX 5#, and OX 10#). a RT-PCR and genomic DNA PCR analysis of CrPIP1;5 in the transgenic Arabidopsis lines and WT plants. b Quantitative RT-PCR analysis of CrPIP1;5 in the transgenic Arabidopsis lines and WT plants.

Additional file 3: Figure S3. Overexpression analyses of CrPIP1;5 in the transgenic Arabidopsis lines (OX 1#, OX 5#, and OX 10#) and stress tolerance analyses of transgenic plants with regards to seed germination rates. a Photographs of the transgenic lines and WT seeds germinated on MS medium or MS medium with NaCl, NaCl plus NaHCO3 (pH 8.2), or mannitol for 7 d. b‒d The seed germination rates in WT and transgenic lines under NaCl (b), NaCl plus NaHCO3 (pH 8.2) (c), and mannitol (d) stresses after 7 d.