Effect of Cold Hardening on Sensitivity of Winter and Spring Wheat Leaves to Short-Term Photoinhibition and Recovery of Photosynthesis

Abstract

Photoinhibition of photosynthesis and its recovery were studied in wheat (Triticum aestivum L.) leaves grown at nonhardening (20°C) and cold-hardening (5°C) temperatures. Cold-hardened wheat leaves were less susceptible to photoinhibition at 5°C than nonhardened leaves, and the winter cultivars, Kharkov and Monopol, were less susceptible than the spring cultivar, Glenlea. The presence of chloramphenicol, a chloroplastic protein synthesis inhibitor, increased the susceptibility to photoinhibition, but coldhardened leaves still remained less susceptible to photoinhibition than nonhardened leaves. Recovery at 50 Mmol m-2 S-1 photosynthetic photon flux density and 20°C was at least biphasic, with a fast and a slow phase in all cultivars. Cold-hardened leaves recovered maximum fluorescence and maximum variable fluorescence in the dark-adapted state during the fast phase at a rate of 42% h-' compared with 22% h-1 for nonhardened leaves. The slow phase occurred at similar rates (2% h-') in cold-hardened and nonhardened leaves. Full recovery required up to 30 h. Fastrecovery phase was not reduced by either lowering the recovery temperature to 50C or by the presence of chloramphenicol. Slowrecovery phase was inhibited by both treatments. Hence, the fast phase of recovery does not require de novo chloroplast protein synthesis. In addition, only approximately 60% of the photochemical efficiency lost through photoinhibition at 5C was associated with lost [14C]atrazine binding and, hence, with damage to the secondary quinone electron acceptor for photosystem II-binding site. We conclude that the decrease in susceptibility to photoinhibition exhibited following cold hardening of winter and spring cultivars is not due to an increased capacity for repair of photoinhibitory damage at 5°C but reflects intrinsic properties of the cold-hardened photosynthetic apparatus. A model to account for the fast component of recovery is discussed.Cold-tolerant cereals such as winter wheat (Triticum aestivum L.) and winter rye (Secale cereale L.) acquire maximum freezing tolerance following prolonged growth and development of seedlings at low, nonfreezing temperatures (0-50C) (18,21 more, damage to the photosynthetic apparatus, typically first expressed as photoinhibition, is exacerbated when high irradiance accompanies the low-temperature exposure (25,27). Typically, plants with larger antenna, such as shade plants (1), or plants with limited potential to fix CO2, such as plants exposed to low temperatures (25, 28), exhibit increased susceptibility to photoinhibition. Photoinhibition reduces the photochemical efficiency of PSII and it is typically detected as a decrease in FV3, Fv/FM, or a decrease in the quantum yield of 02 evolution (4, 14, 17).Greer et al. (10) suggested that the susceptibility of barley (Hordeum vulgare L.) to low-temperature-induced photoinhibition is due to an imbalance between rates of damage and repair of PSII reaction center polypeptides through de novo chloroplastic protein synthesis. However, winter rye (20...

Responses to iron limitation in two colonies of Stylophora pistillata exposed to high temperature: Implications for coral bleaching

“…In contrast, the sharp decrease in photochemical efficiency at elevated temperature with and without DFB (Figs. 1, 2) illustrates a significant impairment of the energy transfer to carbon fixation relative to that at lower temperature, consistent with the effect of high temperature on photoinhibition in plants (Hurry and Huner 1992) and phytoplankton, in the latter particularly in conjunction with trace-metal limitation in stratified surface waters (Falkowski and Raven 2007).…”

Reversible Photoinhibition in Antarctic Moss during Freezing and Thawing

“…In desiccationtolerant Selaginella, zeaxanthin may help to stabilize the LHCII during desiccation and thus provide protection from excess light (Eickmeier et al, 1993). In cold-acclimated cereals, zeaxanthin was found in higher concentrations than in plants not acclimated to cold temperatures (Hurry and Huner, 1992). However, the protective role of zeaxanthin during cold-temperature treatments was not clearly established, since there were no differences observed in the Plant Physiol.…”

The combined effect of arbuscular mycorrhizas and short‐term cold exposure on wheat

“…Mycorrhizas improve nutrition processes and support higher chlorophyll content (Rachel, Reddy & Reddy, 1992) and subsequently lead to a higher production of photosynthates. Adequate photosynthesis is crucial for low-temperature tolerance (Hurry & Huner, 1992), since a higher photosynthetic rate provides the energy for the cellular changes required for the induction of cold acclimation (Oquist, Hurry & Huner, 1993). Chlorosis is frequently observed in low-temperature-sensitive plants (Potvin & Charest, 1991), while in more resistant plants, such as wheat, the chlorophyll synthesis capacity may be increased (Krol & Huner, 1985).…”

“…Plants were grown in a controlled growth chamber (Conviron Model El5) for 7 wk at 25 °C with a 16 h photocycle, 80% r.h., and light intensity of 750 //mol m"^ s '. After this period, and in order to receive a 1-wk 5 °C treatment, half the pots were transferred to a growth chamber (Conviron Model E8) under similar conditions except for light intensity which was lowered at 500 //mol m"^ s~' to reduce the risk of photo-inhibition (Hurry & Huner, 1992). The temperature was lowered stepwise from 25 °C to 5 °C at a rate of 2 °C h"\ According to Lalk & DorfHing (1985), cold exposure of wheat plants during one week at 5 °C is sufficient to induce key metabolite changes.…”