Expression Profiling Of Wheat (Triticum Aestivum L) Seedling In Response To Heat Stress And Isolation Of Heat-Induced Genes

Wheat is one of the most important cereal crops in China. In recent years, the global average temperature has increased due to the enhanced "Greenhouse Effect", heat stress has come to be one of the serious climatic threats for wheat production and causes severe economic losses. However, the molecular basis of crops adaptation to high temperature is not completely characterized. The aim of this study is to analyze the gene expression profile of wheat in response to elevated temperature and isolate the genes induced by heat stress.To define wheat molecular response to elevated growth temperatures, gene expression profiles were examined subjected, to heat stress by using Affymetrix 22k Barley 1 Genechip. cRNA derived from heat treated wheat seedling (38℃ for 1 hour,HS) and untreated wheat seedling(CK) were used to hybridized two chips respectively. As a result, 8486 probe sets produced present calls in those two chips, covered 37.2% of total 22840 probe sets. Among them approximately 10.5% (n=892) probe sets were significantly up or down regulated (ratal >=2 and p-value < 0.05).Semi-quantitative RT-PCR and Realtime RT-PCR were used to verify the hybridization result. Among the 12 genes we have examined, 11 genes exhibited the similar results with the chips. So we believe that the chips result is credible.Analysis showed the differentially expressed genes involved in stress response, signal transduction, transport, photosynthesis, protein metabolism, lipid metabolism and carbohydrate metabolism etc. As expected, a large number of the genes homologous to known chaperones and heat shock proteins in other organisms were highly induced. In addition, several predicted genes including those encoding key enzymes in Ubiquitin-Proteasome pathway had differentially expressed.The complete ORF of two heat-induced genes were cloned by in silico cloning method. Bioinformatic analysis showed that one sequence is encoding a calcium depended protein kinase (CDPK) and another is encoding a Ser/Thr protein kinase. In addition one myristoylation site was detected in the N-terminal of the predicted CDPK and two nuclear targeting signal sequences was found in the N-terminal of the predicted Ser/Thr protein kinase. This result indicate those CDPK and Ser/Thr protein kinase would be anchored to membrane and sorted to nuclear after translation respectively.