Overexpressing a Glycogen Synthase Kinase Gene from Wheat, TaGSK1, Enhances Salt Tolerance in Transgenic Arabidopsis

摘要

TaGSK1, a salt-inducible gene, has a very high identity with mammalian GSK3 which is a highly conserved serine/threonine protein kinase that regulates glycogen synthesis. Overexpression of TaGSK1 reduces cellular osmotic turgor and cellular Na+ content and enhances salt tolerance of transgenic Arabidopsis plants. Biochemical analysis of transgenic lines of Arabidopsis has revealed that the binding property of TaGSK1 protein to CaM was Ca2+ dependent, and the TaGSK1 protein has both Ca2+- and CaM-independent self-phosphorylation and substrate phosphorylation kinase activities. Genomic DNA sequence analysis of wheat has revealed that TaGSK1 gene contains a 703-bp-long intron in the 5′ non-coding region that significantly enhances gene expression and is capable of activating GUS gene transcription. The promoter of TaGSK1 is confirmed to be salt-inducible. The mechanism for salt tolerance mechanism conferred by TaGSK1 was discussed.