Two different strategies for light utilization in photosynthesis in relation to growth and cold acclimation (original) (raw)
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Because of the need for agriculture and landscaping, many overwintering evergreen and biennial species that maintain green leaves over winter were introduced to higher latitudes. The green leaves of introduced overwintering species have to withstand a harsher winter, especially lower temperature, than in their native region of origin. Although the responses and adaptability of photosynthetic apparatus to winter conditions in native overwintering species were widely studied, the experimental results on the introduced overwintering species are very limited. Here, the photosynthetic adaptability during winter was analyzed in two native overwintering species, pine (woody plants), winter wheat (herb), and two introduced overwintering species, bamboo (woody plants), lilyturf (herb). The native species exhibited higher capacity for photosynthetic CO2 fixation and lower susceptibility for photoinhibition than introduced species during winter. Photosynthesis related proteins, such as PsbA, P...
Canadian Journal of Botany, 2002
Cotyledons of jack pine seedlings (Pinus banksiana Lamb.) grown from seeds were expanded at low temperature (5°C), and total Chl content per unit area of cotyledons in these seedlings was only 57% of that observed for cotyledons on 20°C-grown controls. Chl a/b ratio of 5°C-grown jack pine was about 20% lower (2.3 ± 0.1) than 20°C controls (2.8 ± 0.3). Separation of Chl-protein complexes and SDS-PAGE indicated a significant reduction in the major Chl a containing complex of PSI (CP1) and PSII (CPa) relative to LHCII 1 in 5°C compared to 20°C-grown seedlings. In addition, LHCII 1 /LHCII 3 ratio increased from 3.8 in control (20°C) to 5.5 in 5°C-grown cotyledons. Ultrastructurally, 5°C-grown cotyledons had chloroplasts with swollen thylakoids as well as etiochloroplasts with distinct prolamellar bodies. Based on CO 2 -saturated O 2 evolution and in vivo Chl a fluorescence, cotyledons of 5°C jack pine exhibited an apparent photosynthetic efficiency that was 40% lower than 20°C controls. Seedlings grown at 5°C were photoinhibited more rapidly at 5°C and 1200 µmol·m -2 ·s -1 than controls grown at 20°C, although the final extent of photoinhibition was similar. Exposure to high light at 5°C stimulated the xanthophyll cycle in cotyledons of both controls and 5°C-grown seedlings. In contrast to winter cereals, we conclude that growth of jack pine at 5°C impairs normal chloroplast biogenesis, which leads to an inhibition of photosynthetic efficiency.
European Journal of Forest Research, 2016
The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two evergreen tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V cmax), maximum light-driven electron flux (J max), day respiration rate (R d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO 2 assimilation versus intercellular CO 2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V cmax and J max declined with the decrease in winter temperatures, whereas R d at a set common temperature (25°C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.
Relation between photosynthetic capacity and cold hardiness in Scots pine
Physiologia Plantarum, 2006
The seasonal changes in two of the photosynthetic parameters of Scots pine (Pinus sylvestris L.), i.e. the light-saturated assimilation rate (A max ) and the apparent quantum yield (a), were compared with the cold hardiness of needles throughout the course of a year. The data for the comparison were obtained from an experiment with close to ambient and elevated temperatures in opentop chambers. The cold hardiness correlated with the photosynthesis parameters, but the relation was different in the cold acclimation and deacclimation phases, i.e. the same cold hardiness corresponded differently with A max and a in the autumn and spring. The temperature treatment had a clear effect on the relation of a with cold hardiness in the dehardening phase but not during the hardening phase. The ecological significance of the seasonal changes in the photosynthetic capacity, i.e. in A max and a, is discussed.
Characterizing the frost sensitivity of black spruce photosynthesis during cold acclimation
Tree Physiology, 2003
We used photosynthetic light response curves to measure and model the responses of two provenances of 3-year-old black spruce (Picea mariana (Mill.) BSP) seedlings to severe artificial frost treatments applied at 2-week intervals during cold acclimation. Black spruce seedlings responded to cold acclimation with long-term suppression of photosynthetic capacity (A max ) and apparent quantum-use efficiency (α′). Short-term reductions in both photosynthetic parameters following frost treatments were dependent on the extent of cold acclimation of the seedlings and the severity of the frost treatments. Large reductions in A max in response to the frost treatments were observed in seedlings that had undergone little cold acclimation and these reductions were associated with an irreversible reduction in α′. Such seedlings recovered only partially during the subsequent 23 days, whereas seedlings in most other treatments showed complete recovery of A max after 13 days. The impact of frost treatments on A max and α′ did not vary with seedling provenance. We propose an algorithm that predicts the combined effects of cold acclimation and severe freezing temperatures on the extent of the suppression of A max during autumn. The algorithm is based on (1) the maximum A max observed during the growing season, (2) the accumulation of cold degree-days, based on a minimum nocturnal temperature < 5°C, and (3) the severity of freezing temperatures during autumn. The parameters developed in the algorithm showed that cold acclimation of black spruce seedlings had a greater impact on the reduction of A max in autumn than did the severe frost treatments. Mean A max of seedlings subjected to artificial frosts showed a strong correlation with values predicted by the algorithm (r 2 = 0.91).
Planta, 1998
Photosynthetic CO 2 uptake, the photochemical eciency of photosystem II, the contents of chlorophyll and chlorophyll-binding proteins, and the degree of frost hardiness were determined in three-year-old Scots pine (Pinus sylvestris L.) trees growing in the open air but under controlled daylength. The following conditions were compared: 9-h light period (short day), 16-h light period (long day), and natural daylength. Irrespective of induction by short-day photoperiods or by subfreezing temperatures, frost hardening of the trees was accompanied by a long-lasting pronounced decrease in the photosynthetic rates of one-year-old needles. Under moderate winter conditions, trees adapted to a long-day photoperiod, assimilated CO 2 with higher rates than the short-day-treated trees. In the absence of strong frost, photochemical eciency was lower under shortday conditions than under a long-day photoperiod. Under the impact of strong frost, photochemical eciency was strongly inhibited in both sets of plants. The reduction in photosynthetic performance during winter was accompanied by a pronounced decrease in the content of chlorophyll and of several chlorophyll-binding proteins [light-harvesting complex (LHC)IIb, LHC Ib, and a chlorophyll-binding protein with MW 43 kDa (CP 43)]. This observed seasonal decrease in photosynthetic pigments and in pigment-binding proteins was irrespective of the degree of frost hardiness and was apparantly under the control of the length of the daily photoperiod. Under a constant 9-h daily photoperiod the chlorophyll content of the needles was considerably lower than under long-day conditions. Transfer of the trees from short-day to long-day conditions resulted in a signi®cantly increased chlorophyll content, whereas the chlorophyll content decreased when trees were transferred from a long-day to a short-day photoperiod. The observed changes in photosynthetic pigments and pig-ment-binding proteins in Scots pine needles are interpreted as a reduction in the number of photosynthetic units induced by shortening of the daily light period during autumn. This results in a reduction in the absorbing capacity during the frost-hardened state.
Physiologia Plantarum, 2012
The contributions of phenotypic plasticity to photosynthetic performance in winter (cv Musketeer, cv Norstar) and spring (cv SR4A, cv Katepwa) rye (Secale cereale) and wheat (Triticum aestivum) cultivars grown at either 20 • C [non-acclimated (NA)] or 5 • C [cold acclimated (CA)] were assessed. The 22-40% increase in light-saturated rates of CO 2 assimilation in CA vs NA winter cereals were accounted for by phenotypic plasticity as indicated by the dwarf phenotype and increased specific leaf weight. However, phenotypic plasticity could not account for (1) the differential temperature sensitivity of CO 2 assimilation and photosynthetic electron transport, (2) the increased efficiency and light-saturated rates of photosynthetic electron transport or (3) the decreased light sensitivity of excitation pressure and non-photochemical quenching between NA and NA winter cultivars. Cold acclimation decreased photosynthetic performance of spring relative to winter cultivars. However, the differences in photosynthetic performances between CA winter and spring cultivars were dependent upon the basis on which photosynthetic performance was expressed. Overexpression of BNCBF17 in Brassica napus generally decreased the low temperature sensitivity (Q 10 ) of CO 2 assimilation and photosynthetic electron transport even though the latter had not been exposed to low temperature. Photosynthetic performance in wild type compared to the BNCBF17-overexpressing transgenic B. napus indicated that CBFs/DREBs regulate not only freezing tolerance but also govern plant architecture, leaf anatomy and photosynthetic performance. The apparent positive and negative effects of cold acclimation on photosynthetic performance are discussed in terms of the apparent costs and benefits of phenotypic plasticity, winter survival and reproductive fitness.
Frontiers in Plant Science, 2015
Climate change will increase autumn air temperature, while photoperiod decrease will remain unaffected. We assessed the effect of increased autumn air temperature on timing and development of cold acclimation and freezing resistance in Eastern white pine (EWP, Pinus strobus) under field conditions. For this purpose we simulated projected warmer temperatures for southern Ontario in a Temperature Free-Air-Controlled Enhancement (T-FACE) experiment and exposed EWP seedlings to ambient (Control) or elevated temperature (ET, 1.5 • • +
Tree Physiology
During winter evergreens maintain a sustained form of thermal energy dissipation that results in reduced photochemical efficiency measured using the chlorophyll fluorescence parameter F v /F m. Eastern white pine (Pinus strobus L.) and white spruce [Picea glauca (Moench) Voss] have been shown to differ in their rate of recovery of F v /F m from winter stress. The goal of this study was to monitor changes in photosynthetic protein abundance and phosphorylation status during winter recovery that accompany these functional changes. An additional goal was to determine whether light-dependent changes in light harvesting complex II (LHCII) phosphorylation occur during winter conditions. We used a combination of field measurements and recovery experiments to monitor chlorophyll fluorescence and photosynthetic protein content and phosphorylation status. We found that pine recovered three times more slowly than spruce, and that the kinetics of recovery in spruce included a rapid and slow component, while in pine there was only a rapid component to recovery. Both species retained relatively high amounts of the light harvesting protein Lhcb5 (CP26) and the PsbS protein during winter, suggesting a role for these proteins in sustained thermal dissipation. Both species maintained high phosphorylation of LHCII and the D1 protein in darkness during winter. Pine and spruce differed in the kinetics of the dephosphorylation of LHCII and D1 upon warming, suggesting the rate of dephosphorylation of LHCII and D1 may be important in the rapid component of recovery from winter stress. Finally, we demonstrated that light-dependent changes in LHII phosphorylation do not continue to occur on subzero winter days and that needles are maintained in a phosphorylation pattern consistent with the high light conditions to which those needles are exposed. Our results suggest a role for retained phosphorylation of both LHCII and D1 in maintenance of the photosynthetic machinery in a winter conformation that maximizes thermal energy dissipation.