INSILICO EXPRESSION ANALYSIS OF AQUAPORIN GENES IN WHEAT

摘要

The Major Intrinsic Protein (MIP) family encodes transmembrane water channels that transport water through cellular membranes. So far, MIP gene families have been characterized in A. thaliana (35 genes; Johanson et al, 2001), maize (33 genes; Chaumontet al, 2001), and rice (33-38 genes; Sakurai et al, 2005; Forrest and Bhave, 2007), consisting of four main subfamilies known as the plasma membrane intrinsic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin26-like membrane intrinsic proteins (NIPs) and small, basic membrane intrinsic proteins (SIPs). Of these, the PIPs and TIPs have been extensively studied but little remains known of the NIPs and SIPs. Water is vital for many fundamental plant processes including cell turgor and elongation, stomatal movement, phloem loading, photosynthesis and seed germination. In plants, the MIP family controls transcellular water transport and is thought to play a significant role in many of these processes (Johansson et al, 2000). PIPs and TIPs haveshown specific transport of water and/or alternative molecules (Kaldenhoff and Fischer, 2006). Plant MIPs are also associated with response to abiotic stresses including salt, drought, osmotic and chilling, all of which can affect plant growth, productivity and survival. Plants have responded through up- or down-regulation of PIP or TIP transcripts and/or proteins (Sakurai et al, 2005; Guo et al, 2006; Jang et al, 2004: Alexandersson et al, 2005), and transgenic plants with MIP gene-knockouts or overexpression have shown altered tolerance to these conditions compared to the wild type (Yu et al, 2005). Very little is known about the MIP family in wheat, the world's largest cereal crop. Our work has identified 35 PIP and TIP genes in wheat (Forrest and Bhave, communicated), but their localization remains unknown. This work aimed to utilize the synteny between rice and wheat to search for wheat expressed sequence tags (ESTs) for use in tissue localization prediction, knowledge which might help elucidatetheir roles.