Different response of GTP cyclohydrolase I gene from grape under abiotic stresses

Folates are a vital necessity for the retention of normal cellular activity. In contrast to humans, other organisms including plants gain folate coenzymes via de novo synthesis. GTP cyclohydrolase I (gtpch I, EC ۳.۵.۴.۱۶) catalyzes the first step of the biosynthesis of tetrahydrofolate (FH۴) in plants by the conversion of GTP to dihydroneopterin triphosphate and formic acid. In this research, the expression pattern of the Vvgtpch I gene was assayed in different organs of the grape by the semi-quantitative RT-PCR. The analyses demonstrated that the Vvgtpch I gene was expressed in all grape organs. The highest amounts of expression were obtained in berry and leaf, whereas the lowest amount of Vvgtpch I transcript was related to the cluster. The response of Vvgtpch I gene to abiotic stresses was also investigated under the alkali and cold stresses by the semi-quantitative RT-PCR. Under the alkali stress, the transcript level of Vvgtpch I gene decreased considerably. Similar to the alkali stress, the transcript level of Vvgtpch I gene decreased under cold stress as well. To analyze the Vvgtpch I gene expression under oxidative stress, different treatments were applied such as chemical inducers, heavy metals, and plant growth regulators to trigger the production of reactive oxygen species. The Vvgtpch I showed a strong increase and a moderate increase in the transcript amount with Cu۲+ and H۲O۲, respectively. Whereas, its transcript level was relatively down-regulated by the heavy metals and hormonal treatments, and almost disappeared by diamide.

Keywords:

folate , Gene Expression , Oxidative stress , reactive oxygen species , Abiotic stress