Changes in plasmalemma K+Mg2+-ATPase dephosphorylating activity and H+ transport in relation to seasonal growth and freezing tolerance of Festuca pratensis Huds

Changes in plasmalemma K+Mg2+-ATPase dephosphorylating activity and H+ transport were examined in freezing-tolerant and non-tolerant genotypes of the perennial grass species Festuca pratensis Huds. Enzyme activity and delta μH+ were measured in plasmalemma fractions isolated from basal nodes and roo...

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Published in:	Journal of plant physiology Vol. 165; no. 8; pp. 825 - 832
Main Authors:	Darginaviciene, J, Pasakinskiene, I, Maksimov, G, Rognli, O.A, Jurdoniene, S, Sveikauskas, V, Bareikiene, N
Format:	Journal Article
Language:	English
Published:	Jena Elsevier 26-05-2008
Subjects:	Acclimatization Adenosine Triphosphatases - metabolism adenosinetriphosphatase Biological and medical sciences Biological Transport Cell Membrane - enzymology Cell physiology cold stress cold tolerance dephosphorylation Festuca - enzymology Festuca - growth & development Festuca pratensis forage grasses Freezing Fundamental and applied biological sciences. Psychology hydrogen ions Hydroponics ion transport Phosphorylation plant growth Plant physiology and development plant stress plasma membrane Plasma membrane and permeation Protons Seasons Festuca pratensis Plasmalemma Freezing tolerance Monocotyledones Gramineae Growth Angiospermae Tolerance K+Mg2+-ATPase Spermatophyta H+ transport Low temperature
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Summary:	Changes in plasmalemma K+Mg2+-ATPase dephosphorylating activity and H+ transport were examined in freezing-tolerant and non-tolerant genotypes of the perennial grass species Festuca pratensis Huds. Enzyme activity and delta μH+ were measured in plasmalemma fractions isolated from basal nodes and roots. Three types of experiments were undertaken: (i) a field experiment, utilizing the seasonal growth and cessation cycle of a perennial plant; (ii) a cold acclimation experiment in hydroponics; and (iii) an instant freezing test. A specific fluctuation in K+Mg2+-ATPase activity was found throughout the seasonal growth of the plants (i). The K+Mg2+-ATPase activity peaks for both the basal node and the root plasmalemma were determined early in the spring before the renewal of growth. The lowest activity values in roots occurred at the time approaching flowering, and in basal nodes at the transition into the growth cessation. The K+Mg2+-ATPase activity was approximately 50% lower in the basal node plasmalemma of freezing-tolerant plants than of non-tolerant ones, when assessed at the optimal growth stage in hydroponics. In hydroponics (ii) and in the freezing test (iii), temperature stress was followed by a more pronounced change in the level of K+Mg2+-ATPase activity than in that of H+ transport, and this change was more clearly differentiated in the basal node plasmalemma of contrasting genotypes than in the roots. Stress response was manifested differently in freezing-tolerant and non-tolerant plants at cold acclimation (4-2 °C) and at freezing (-8 °C) temperatures. Proton transport regulation via coupled changes in the hydrolysed ATP/transported proton ratio, as an attribute of freezing-tolerant plants, is discussed.
Bibliography:	http://dx.doi.org/10.1016/j.jplph.2007.07.009 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0176-1617 1618-1328
DOI:	10.1016/j.jplph.2007.07.009