Role of Aquaporin Gene Family Towards Abiotic and Biotic Stress Tolerance in Brassica rapa

Aquaporin (AQP) genes are those which have been so far reported as responsive for water transportation in plants. The aquaporin proteins are present in diverse forms in plants, where they function in transport of water and nutrient molecules through living membranes, and might be essential for survival under salt and drought stresses. In this study, we have explored and identified 59 AQP genes in Brassica rapa database and Br135K microarray dataset. Phylogenetic analysis revealed four subfamilies, including plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), NOD26-like intrinsic proteins (NIPs), and small basic intrinsic proteins (SIPs). Here, we have selected PIP subfamily genes for detailed qPCR expression analysis in response to cold, salt, drought, and water logging conditions as well as ABA (abssicic acid) treatment and Fusarium oxysporum f. sp. conglutinans infection. All BrPIP genes showed organ-specific expression. Twelve out of 22 BrPIP genes were differentially expressed upon cold treatment in two B. rapa inbred lines (Chiifu and Kenshin). Seven and seventeen BrPIP genes showed up-regulation under drought and salt stresses respectively. Whereas, 18 BrPIP genes were responsive to ABA treatment, and all BrPIP genes showed down-regulation under water logged condition. Four BrPIP genes were found responsive to F. oxysporum f. sp. conglutinans infection. Therefore, this study gives a comprehensive report of AQPs in B. rapa on expression profile 22 members of the BrPIPsubfamily, which could be provided a basis to elucidate the stress-related biological functions of specific PIP gene. (213003-04-3-SB420)