Tuesday, November 6, 2007
158-6
Real Time Quantitaive PCR of Wheat Fructan Genes Induced by Cold.
Pasajee Kongsila, Purdue Agronomy Dept., Lilly Hall of Life Sciences, 915 W. State Street, West Lafayette, IN 47907, Thomas Housley, 915 West State Street, Purdue University-Agronomy Dept., Purdue University, Agronomy Dept., West Lafayette, IN 47907-2045, and Joseph Anderson, Agronomy, Purdue University, 915 W. State St., West lafayette, IN 47907-2054.
Fructans, oligomers of fructose, are synthesized by approximately 15% of flowering plant species and a small number of bacterial species. Plants in the Poaceae family synthesize graminan-type fructans which are branch-types containing both β (2,1) and β (2,6)- linked fructofuranosyl units. The objective of this research was to study the gene expression of enzymes of fructan biosynthesis under cold stress: sucrose:sucrose 1-fructosyltransferase (1-SST: EC 2.4.1.99), sucrose:fructan 6-fructosyltransferase (6-SFT: EC 2.4.1.100) and Fructan:fructan 1-fructosyltransferase (1-FFT: EC 2.4.1.10) and degradation upon warming: β-(2,1)-fructan exohydrolase (1-FEH: EC 3.2.1.80), β-(2,6)-fructan exohydrolase (6-FEH: EC 3.2.1.154). Two-week-old wheat seedlings (Triticum aestivum L. cv Patterson) grown at 25°C, in a 12-hour-light period were transferred to cold temperature (10°C), to induce fructan biosynthesis. After 5 days in the cold, plants were transferred to 25°C, in a 12-hour-light period for 3 days to monitor fructan degradation. Plants were harvested two times a day: After 12 hours in the dark and after 9 hours in the light. Total fructan in blade and shoot tissues were measured as fructose equivalents by assay with anthrone and patterns of DP of fructan in both tissues were compared by HPLC. Under cold induction, fructan concentration in both tissues increased continuously, and decreased sharply in 25°C within 3 days. Expression study determined by quantitative real-time PCR showed that 1-SST, 6-SFT and 1-FFT genes were highly regulated from the first day of cold induction in both blade and shoot tissues compared to expression of the control group at 25°C. During the fructan degradation study at 25°C, 1-SST, 6-SFT and 1-FFT expression decreased to reach the same level observed in the control group within 24 hours. However, FEHs expression in blade and shoot tissues was different. Significance of the results FEHs will be discussed.