1,721,069 research outputs found
Sunflower seedlings subjected to incresing water deficit stress: oxidative stress and defence mechanisms
No full textSunflower seedlings (Helianthus annuus cv. Licia Stella) reached a mild, moderate and severe level of water deficit stress after 5,8 and 11 days of soil water depletion, respectively. At a moderate level of water deficit stress, an elestic adjustment occurred. At the same time, in response to a minor osmotic potential and an intermediate rate of water potential decrease, glutathione level increased and enzyme activities related to the ascorbate/glutathione cycle were induced. At severe water deficit stress, the efficiency of this defence mechanism fell, oxidative processes intensified and soluble protein content decreased further. The results of the present experiment suggest that during water deficit stress the water status of the plants plays a key role in the activation of defence mechanisms
Plasma-membrane proteins in water-stressed sunflower seedlings
No full textIn sunflower seedlings either regularly watered or subjected to water stress by withholding water for 5 days, plasma membrane was isolated by partitioning in an aqueous polymer two-phase system. In the stressed seedlings an osmotic adjustment of 0.1 MPa took place. Water deficit conditions determined an increase in membrane permeability and in the recovery of plasma membrane proteins. Total and soluble protein levels decreased by 9.4 and 45.8% respectively in the stressed seedlings. The sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the soluble proteins and plama membrane proteins did not show qualitative changes in the protein patterns of both the control and the stressed seedlings. Several quantitative differences in the levels of plasma membrane proteins were observed: the 60, 56 and 37 KDa bands, as well as the 37 to 20.1 KDa group, reached higher levels under stress. These last polypeptides can be identified as peripheral plasma membrane proteins of the bilayer
Elementi minerali ed acidi organici nel succo cellulare di foglie di Ramonda serbica sottoposta a disidratazione e reidratazione
No full textNADPH ossidasi e lipidi nelle membrane plasmatiche di radici di grano cresciuto in carenza ed eccesso di rame
No full textActivated oxygen production and detoxification in wheat plants subjected to a water deficit programme
No full textWheat plants (Triticum durum L. cv. Ofanto) were grown in a controlled environment. In one set, control plants were regularly watered; the other set of plants was subjected to two water deficit periods obtained by withhoding water and rewatering to field capacity at the end of the frst period. After both periods of stress, water potential, pressure potential and relative water content (RWC) decreased; osmotic potential decreased by 0.3 MPa only after the second period of stress. In both treatments no osmoregulation mechanism occurred, however, an elastic adjustment took place and turgor was maintained at positive levels. Following the first treatment the good functionality of the ascorbate/gltathione cycle allowed the plants to maintain hydrogen peroxide to the control level despite a greater capacity of the thylakoid membranes to leak electrons towards oxygen; moreover, the ascorbate (AsA)/dehydroascorbate (DHA) ratio was unchanged while reduced glutathione (GSH)/oxidized glutathione (GSSG) increaed in comparison with the control. Following the second period of stress, the decreased enzyme defence aactivities of the glutathione reductase (GR), dehydroascorbate reductase (DHAR) and ascorbate peroxidase (AsAP) together with a minor glutathione content might be a consequence of a reduced rate of activated oxygen production
Induction of defence mechanism in sunflower seedlings subjected to increasing water deficit stress
No full textProline accumulation related to water status in sunflower seedlings subjected to drought
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