Isolation and characterization of a salt-induced SKD1-like gene in ice plant

• Main Authors: YuHui Hung, 洪郁惠
• Other Authors: Hungchen Emilie Yen
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/44850421914843420010

碩士 === 國立中興大學 === 植物學系 === 87 === Common ice plant (Mesembryanthemum crystallinum L.) is able to survive in high saline and water-deficit environment. By using substractive hybridization and selective amplification of differentially-expressed cDNAs, several salt-induced cDNA clones have been isolated. In this study, we focused on examining a partial-length cDNA clone SI1. To obtain its full length cDNA sequence, two sets of gene-specific primers were designed according to known SI1 sequence. One 1000 bp fragment was obtained by 5’-RACE (rapid amplification of cDNA ends). The sequence aligned to SI1 and the total length was 1219 bp. Deduced amino acid sequences showed 69.7 % and 70 % similarity to a SKD1 (suppressor of K+ transport growth defect) protein of human (AF038960) and mouse (P46467), respectively, and 95 % similarity to a putative suppressor protein of Arabidopsis thaliana (AC005824). Therefore, we named it as mcSKD1. All SKD1 sequences are hydrophilic and contain one ATP binding site. Southern blot analysis showed that only one copy of the gene existed in haploid genome. Northern blot analyses showed that mcSKD1 was expressed in callus grown in different NaCl concentrations. The highest expression occurred in treatments of 200 or 300 mM NaCl. At whole plant level, mcSKD1 was expressed in all tissues examined and the expression of mcSKD1 increased as the concentration of NaCl in roots, stems and leaves increased. The expression of mcSKD1 was higher in new leaves than old leaves in treatment of 200 mM NaCl. The expression of mcSKD1 was most prominent in 400 mM NaCl- grown roots of hydroponically-grown ice plant. When callus was grown under potassium-deficit medium for five or ten days, the expression of mcSKD1 was increased. The expression of mcSKD1 in related to the ion homeobalance, especially Na+ and K+, are discussed.