The characterization and expression analysis under stress conditions of <i>PCST1</i> in <i>Arabidopsis</i>

Analysis of <i>PCST1</i> expression characteristics and the role of <i>PCST1</i> in response to osmotic stress in <i>Arabidopsis thaliana</i>. The structure of <i>PCST1</i> was analyzed using Bioinformatics method. Real-time PCR, GUS tissue localization and subcellular localization were adopted to analyze the expression pattern of <i>PCST1</i> in Arabidopsis. To validate the transgenic positive strain of <i>PCST1</i> using Real-time PCR, overexpression experiments were performed in wild type. Full-length cDNA was cloned and connected into a binary vector with 35S promoter, and the construction was transformed into wild type. With NaCl and mannitol treatments, the germination rate, green leaves rate, physiological indexes were carried out and counted in Arabidopsis with overexpression of <i>PCST1</i> and T-DNA insertion mutants. The molecular mechanism of <i>PCST1</i> in response to osmotic stress in Arabidopsis was analyzed. Based on the bioinformatic analysis, PCST1 is a hydrophobin with 403 amino acids, and the molecular weight is 45.3236 KDa. It contains only the START (the lipid/sterol – binding StAR – related lipid transfer protein domains) conservative domain. PCST1 possesses phosphatidylcholine binding sites and transmembrane region. Expression pattern analysis showed that expression of <i>PCST1</i> increased with time. The <i>PCST1</i> widely expressed in Arabidopsis, including roots, axils of stem leaves, flowers (sepal, conductive tissue of the petal, thrum, anther and stigmas), and the top and basal parts of the siliquas. It mainly localized in cell membrane. The overexpression of <i>PCST1</i> enhanced the sensitivity to osmotic stress in <i>Arabidopsis</i> based on the germination rate. While expression of <i>PCST1</i> decreased, and the sensitivity to osmotic stress had no obvious change in Arabidopsis. Its molecular mechanism study showed, that PCST1 response to osmotic stress resistance by regulating the proline, betaine synthesis, as well as the expression of key genes <i>SOS, NCED, CIPK</i>. PCST1 is composed of 403 amino acids. The START conservative domain, a transmembrane structure, the phosphatidyl choline binding sites are contained in PCST1. It is localized in cytoplasmic membrane. The <i>PCST1</i> widely expressed in the root, leaf, flower and siliquas. NaCl and mannitol suppressed the expression of <i>PCST1</i> and PCST1 can negatively control action of <i>Arabidopsis</i> in the osmotic stress. PCST1 regulates the synthetic pathway of proline, betaine and the expression of <i>SOS, NCED</i> and <i>CIPK</i> in response to the osmotic stress resistance.