Characterization of the aquaporin family genes and stress responsive expression profiling in Brassica rapa

다국어 초록 (Multilingual Abstract)

Efficient infiltration of water through cell membranes is arbitrated by a family of transmembrane water channels called aquaporins (AQPs). Aquaporin belongs to a highly conserved group of membrane proteins called major intrinsic proteins that facilitate the transport of water and a variety of low molecular weight solutes across biological membranes,which is essential for plants to survive in stress conditions. This study identified 59 BrAQP genes from B. rapa database and Br135K microarray dataset, which was formed by applying low-temperature stresses to contrasting Chinese cabbage two inbreed lines, Chiifu and Kenshin. Based on phylogenetic analyses of BrAQPs revealed four distinct subfamilies, such as plasma membrane intrinsic proteins (PIP), tonoplast intrinsic proteins (TIP), NOD26-like intrinsic proteins (NIP), small basic intrinsic proteins (SIP) with aquaporin of Tomato and Arabidopsis thaliana. All BrAQP genes were firstly examined through homology study with existing biotic and abiotic stress resistance-related aquaporin genes of other plant species and found a high degree of homology. We selected PIP subfamily genes for expression analysis based on microarray data with high and differential transcript abundance levels and homology study with stress related aquaporin genes of other plant species. In our study, we characterized all B. rapa aquaporin genes and understanding the BrPIP subfamily gene function in plants under various environmental stimuli, the expressions of BrPIP genes under various abiotic stress conditions including cold, drought, salinity, water logging, ABA treatment and Fusarium oxysporum f. sp. Conglutinans infection were investigated by a quantitative real-time reverse transcription-PCR analysis. In our expression analysis, 4 BrPIP genes showed responsive expression against F. oxysporum f. sp. Conglutinans infection. The selected genes showed an organ-specific expression, and 12 out of 22 BrPIP genes were differentially expressed in Chiifu compared to Kenshin under cold stresses. Only 7 genes showed up regulation under drought stress and incase of salt stress 17 BrPIP genes were more responsiveness. Additionally, 18 BrPIP genes were up regulated by ABA treatment and all BrPIP genes showed down regulation under water logging stress. Together with expression and bioinformatic analyses, our results provides novel basis to allocate the stress-related biological function to each PIP gene.