and OH • ). Under drought stress, these may damage plants by oxidizing photosynthetic pigments, membrane lipids, proteins and nucleic acids (Smirnoff 1993, Reddy et al. 2004. Oxidative stress is caused by the accumulation of ROS during drought. To eliminate ROS, all plants are endowed with detoxification mechanisms, including both
AbstractIn this study, some morphological, physiological and biochemical parameters of two chickpea cultivars, cv. Gökçe and Canıtez, were analysed to understand their tolerance to drought stress. Twenty-day-old plants were subjected to three different regimes of drought stress by withholding water for 3, 5 or 7 days, and then rewatering for 2 days after the initial 7 days of drought stress. Drought treatments only reduced shoot elongation in the Canıtez cultivar. Leaf production and fresh biomass decreased in both cultivars under all drought treatments, however to a greater extent in Canıtez. In both cultivars, malondialdehyde, proline and anthocyanin accumulation increased significantly, whereas relative water content declined under drought stress. The total chlorophyll and carotenoid contents of Gökçe were not affected by drought stress, whereas the chlorophyll content of Canıtez increased greatly at the end of the treatments. Using chlorophyll a fluorescence measurements, we found that extended drought treatment caused photoinhibition of PSII activity in both cultivars. However, this was greater in Canıtez, especially under severe drought stress. Although Canıtez recovered quickly from drought stress and exhibited a good ability to overcome drought stress, via activation of many protection mechanisms such as increasing antioxidant enzymes and proline and anthocyanin accumulation during vegetative stage, our results show that Canıtez is less drought tolerant than Gökçe.
Mercury (Hg) is a highly toxic heavy metal for all organisms. In the present study, the mitigative role of 190 mg/L and 380 mg/L doses of green tea extract (GTex) against mercury(II) chloride (HgCI
2
)-induced toxicity was evaluated in
Allium cepa
L. For this aim, selected physiological, genotoxicity, and biochemical parameters as well as meristematic cell injuries in the roots were investigated. Ratios of catechin and caffeine in GTex were determined by HPLC analysis. Also, free radical scavenging activity of GTex was tested against superoxide and hydrogen peroxide radicals. As a result of HgCI
2
application, germination percentage, root elongation, weight gain, and mitotic index (MI) declined, while the frequency of micronucleus (MN), chromosomal abnormalities (CAs), and meristematic cell damages increased. HgCI
2
administration also led to a significant increase in malondialdehyde content, superoxide dismutase, and catalase activities which are signs of oxidative stress. On contrary, applications of GTex together with HgCI
2
reduced HgCI
2
-induced adverse effects in all parameters in a dose-dependent manner. Antioxidant components in GTex were listed as caffeine, epigallocatechin gallate, epigallocatechin, epicatechin gallate, and catechin according to their abundance. GTex exhibited a strong scavenging ability in the presence of superoxide and hydrogen peroxide radicals. The present study revealed the strong protective capacity of GTex against HgCI
2
-induced toxicity in
A. cepa
owing to its high antioxidant content with a multifaceted perspective. With this study, a reliable starting point was established for future studies investigating the more common and diverse use of GTex against toxic substances.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.