Cloning and expression of tonoplast membrane intrinsic protein genes in leaves of Vitis heyneana and overexpression of VhTIP2;1 in Arabidopsis confer drought tolerance

Vitis heyneana is widely distributed in Guizhou Province and has high drought resistance. The role of aquaporin proteins (AQPs) has been studied extensively in plants, and the expression of tonoplast membrane intrinsic protein (TIP) genes is vital for drought tolerance. Nonetheless, information on TIPs in V. heyneana is inadequate. In the present study, nine VhTIP genes from V. heyneana cv. 'Huaxi-9' were cloned and characterized. The open reading frames of nine genes contained 750-780 bases and encoded 249-259 amino acids. The amino acid sequence has a typical MIP family domain containing a unique SGGHINPAVT sequence. Moreover, VhTIPs expressed four patterns in the leaf of 'Huaxi-9', and the expression of VhTIP2;1 under drought conditions was the most upregulated gene. In addition, Arabidopsis transgenic plants that overexpressed VhTIP2;1 had a higher leaf water potential, leaf relative water content, and proline content, as well as a lower relative electrical conductivity and malondialdehyde content than wild-type (WT) plants under drought stress, indicating that transgenic A. thaliana has greater tolerance to drought stress than non-transgenic plants. This study provides valuable information to better explain the characterization and function of VhTIP2;1 in regulating drought resistance in Chinese wild grape plants and establishing molecular drought-resistant4 breeding systems in grapes.