title: Reduced light and moderate water deficiency sustain nitrogen assimilation and sucrose degradation at low temperature in durum wheat.
abstract: The rate of carbon and nitrogen assimilation is highly sensitive to stress factors, such as low temperature and drought. Little is known about the role of light in the simultaneous effect of cold and drought. The present study thus focused on the combined effect of mild water deficiency and different light intensities during the early cold hardening in durum wheat (Triticum turgidum ssp. durum L.) cultivars with different levels of cold sensitivity. The results showed that reduced illumination decreased the undesirable effects of photoinhibition in the case of net photosynthesis and nitrate reduction, which may help to sustain these processes at low temperature. Mild water deficiency also had a slight positive effect on the effective quantum efficiency of PSII and the nitrate reductase activity in the cold. Glutamine synthesis was affected by light rather than by water deprivation during cold stress. The invertase activity increased to a greater extent by water deprivation, but an increase in illumination also had a facilitating effect on this enzyme. This suggests that both moderate water deficiency and light have an influence on nitrogen metabolism and sucrose degradation during cold hardening. A possible rise in the soluble sugar content caused by the invertase may compensate for the decline in photosynthetic carbon assimilation indicated by the decrease in net photosynthesis. The changes in the osmotic potential can be also correlated to the enhanced level of invertase activity. Both of them were regulated by light at normal water supply, but not at water deprivation in the cold. However, changes in the metabolic enzyme activities and osmotic adjustment could not be directly contributed to the different levels of cold tolerance of the cultivars in the early acclimation period.
authors.affiliation: Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik u. 2, Martonvásár 2462, Hungary. Electronic address: majlath.imre@agrar.mta.hu.
authors.forename: Imre
authors.initials: I
authors.lastname: Majláth
authors.affiliation: Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik u. 2, Martonvásár 2462, Hungary.
authors.forename: Eva
authors.initials: E
authors.lastname: Darko
authors.affiliation: Department of Plant Biology and Plant Biochemistry, Corvinus University of Budapest, Ménesi u. 44, Budapest 1118, Hungary.
authors.forename: Balázs
authors.initials: B
authors.lastname: Palla
authors.affiliation: Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik u. 2, Martonvásár 2462, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Nagy
authors.affiliation: Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik u. 2, Martonvásár 2462, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Janda
authors.affiliation: Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik u. 2, Martonvásár 2462, Hungary.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Szalai
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects; D002245:Carbon Dioxide / Q000378:metabolism; D003080:Cold Temperature; D004579:Electron Transport / Q000528:radiation effects; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D008027:Light; D050901:Nitrate Reductase / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009995:Osmosis / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects; D054046:Plant Stomata / Q000502:physiology / Q000528:radiation effects; D013395:Sucrose / Q000378:metabolism*; D014908:Triticum / Q000201:enzymology / Q000378:metabolism* / Q000528:radiation effects*; D014867:Water / Q000378:metabolism*; D043324:beta-Fructofuranosidase / Q000378:metabolism
chemical_list: D014867:Water; D002245:Carbon Dioxide; D013395:Sucrose; D050901:Nitrate Reductase; D043324:beta-Fructofuranosidase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen
keywords: Cold; Drought; Durum wheat; Invertase; Light; Nitrogen assimilation