ABSTRACT
A comparative study of the response to waterlogging in a tolerant (Trifolium repens L., white clover cultivar Rivendel) and susceptible (Trifolium pratense L., red clover cultivar Raya) plants was undertaken to reveal the possible link between plant performance and oxidative stress protection mechanisms in leaves. Two weeks of soil waterlogging induced visible leaf damage in the susceptible genotype. In the tolerant one, signs of stress suffering appeared a week later. Waterlogging induced hydrogen peroxide accumulation in both clover species. The content of lipid hydroperoxides markedly increased in the sensitive plants along with stress prolongation, while in the tolerant ones their initial rise was followed by return to control levels. In the leaves of both genotypes ascorbic acid content increased following treatment, accompanied by transient increase in oxidized ascorbate. Superoxide dismutase (SOD) isoforms responded differently to the treatment, CuZn SOD isoforms being inhibited; catalase activity diminished while peroxidase activity increased and a new peroxidase isoform was detected after prolonged waterlogging in both clover species. Results support more pronounced oxidative secondary stress in red clover leaves as a result of waterlogging with progressively increased oxidative membrane injury, protein loss, and peroxidase activity enhancement. White clover presented relative protein stability and earlier and more active ascorbate involvement in the antioxidative protection.
Subject(s)
Adaptation, Physiological/physiology , Antioxidants/metabolism , Floods , Oxidative Stress/physiology , Plant Leaves/physiology , Soil , Trifolium/physiology , Adaptation, Physiological/genetics , Genotype , Hydrogen Peroxide/metabolism , Malondialdehyde/metabolism , Oxidative Stress/genetics , Plant Leaves/metabolism , Plant Proteins/metabolism , Trifolium/genetics , Trifolium/metabolismABSTRACT
Three varieties (cv. Pobeda, Katya and Sadovo) of winter wheat (Triticum aestivum), differing in their agronomic characteristics, were analysed during progressive soil water stress and recovery at early vegetation stages. Changes in abscisic acid content, SDS-PAGE and immunoblot profiles of proteins that remained soluble upon heating were monitored. Initially higher ABA content in control Pobeda and Katya corresponded to earlier expression of the studied late embryogenesis abundant (LEA) proteins. A combination of higher ABA content, early immunodetection of dehydrins, and a significant increase of WZY2 transcript levels were observed in drought-stressed leaves of the tolerant variety Katya. One-step RT-PCR analyses of some acidic dehydrin genes (WCOR410b, TADHN) documented their relatively constant high expression levels in leaves under drought stress during early vegetative development. Neutral WZY2 dehydrin, TaLEA2 and TaLEA3 transcripts accumulated gradually with increasing water deficit. Delayed expression of TaLEA2 and TaLEA3 genes was found in the least drought-tolerant wheat, Sadovo. The expression profile of WZY2 revealed two distinct and separate bands, suggesting alternative splicing, which altered as water stress increased.
Subject(s)
Abscisic Acid/analysis , Droughts , Plant Proteins/metabolism , Triticum/metabolism , Water/analysis , Gene Expression Profiling , Gene Expression Regulation, Plant , RNA, Plant/genetics , Stress, Physiological , Triticum/genetics , Triticum/growth & developmentABSTRACT
The response of tobacco plants (Nicotiana tabacum L.)--non-transformed and transformed with a metallothionein gene MThis from Silene vulgaris L.--to increase cadmium supply in the nutrient solution was compared. The transgenic plants accumulated significantly more Cd both in the roots and the leaves. Visual toxicity symptoms and disturbance in water balance were correlated with Cd tissue content. Treatment with 300 microM CdCl(2) resulted in inhibition of photosynthesis and mobilization of the ascorbate-glutathione cycle. Treatment with 500 microM CdCl(2) led to irreversible damage of photosynthesis and oxidative stress. An appearance of a new peroxidase isoform and changes in the leaf polypeptide pattern were observed at the highest Cd concentration. The level of non-protein thiols gradually increased following the Cd treatment both in transgenic and non-transformed plants.
