بررﺳﻲ روﻧﺪ ﺗﻐﻴﻴﺮات ﻣﺤﺘﻮی α - ﺗﻮﻛﻮﻓﺮول ﺳﺎﻗﻪ ﮔﻨﺪم در ﻓﺮاﻳﻨﺪ اﻧﺘﻘﺎل ﻣﺠﺪد ذﺧﺎﻳﺮﺳﺎﻗﻪ ﺗﺤﺖ ﺗﻨﺶ خشکی

Stem reserves remobilization is one of the most important mechanisms of terminal drought tolerance in monocarpic plants such as wheat that requires the initiation of whole-plant senescence. Plant senescence is also related to an increase in reactive oxygen species (ROS), lipid peroxidation and cell membrane damage, finally leads to premature cell death under stress. Increased oxidative stress defense mechanism is one of the useful approaches to protect plant from premature cell death to sustain stem reserve remobilization under drought condition. The plants overcome oxidative stress by two mechanisms: enzymatic and non -enzymatic detoxification. Vitamin E is a non -enzymatic detoxification mechanism. α – tocopherol is the major compound of Vitamin E. For this purpose, the changes in content of α - tocopherol in peduncle was studied during under a progressive post-anthesis drought stress. Experiments were performed on two wheat genotypes NO.49 and NO.14 (differing in their stem remobilization during 30 days after flowering under drought stress). NO.49 peduncle had remarkably higher stem reserves remobilization efficiency compared to NO.14. To determine the content of α - tocopherol, peduncle samples of both genotypes after extraction with 100% methanol and preparations were injected into the HPLC system with a C18 column. The results ۴ showed that the content of α - tocopherol in NO.49 genotype under drought stress at 10 days after flowering (initiation stage of remobilization) was increased compared with normal conditions and in the 20 days after flowering (intensified stage of remobilization) had the maximum increase in α – tocopherol content, while for NO.14 at 20 days no significant increase in α – tocopherol content was observed under stress compared with normal. Simultaneous in increasing content of α – tocopherol with increasing reserves remobilization in NO.49 peduncle indicated high efficiency detoxification of peduncle under drought stress, so the plant can use beneficial from senescence-induced stress to increase the efficiency of remobilization.