Abstract
Abiotic stresses are determinant factors of plant growth, development and production. Heat is a biotic stress that impact plants in many regions of the world. Wheat is affected by heat stress during its life cycle especially in arid and semiarid regions of the world. Nine commercial Egyptian bread wheat varieties with different biotic and abiotic stress tolerance were used in this study. Expression of two Heat Shock Protein (HSP 17, HSP90) and two abiotic stress-induced transcription factors (DREB2, NAC6D) was investigated using semiquantitative PCR of cDNA generated from total RNA under normal and heat stress (40 degrees C). Results showed substantial differences in the response of wheat varieties in HSP 17, HSP90, DREB2 genes expression in response to high temperature whereas NAC6D showed up-regulation in all varieties compared to normal condition.
Giza168 and Sids 1 showed high induction of the four investigated genes. They represented 70.6, 55.2 (HSP 17), 4.4, 2.7 (HSP90), 7.5, 4.8 (DREB2) and 2.2, 2 (NAC6D) folds of expression level relative to expression of minimal variety. High induction of gene expression in Giza168 and Sidsl seems to be linked to their tolerance to abiotic and biotic stresses. Giza168 is tolerant to high temperature, drought and rusts whereas Sids 1 is tolerant to high temperature, salinity and yellow rust. Results of this study will contribute in evaluation of commercial new wheat varieties and their possible integration in wheat breeding programs.