Photoinhibition resistance

Tardy F and Havaux M (1996) Photosynthesis, chlorophyll fluorescence, light-harvesting system and photoinhibition resistance of a zeaxanthin-accumulating mutant of Arabidopsis thaliana. J Photochem Photobiol B-Biol 34 87-94 Tardy F and Havaux M (1997) Thylakoid membrane fluidity and thermostabiUty during the operation of the xanthophyll cycle... 

Maxwell DP, Falk S and HunerNPA (1995) Photosystem II excitation pressure and development of resistance to photoinhibition. 1. Light harvesting complex II abundance and zeaxanthin content in Chlorella vulgaris. Plant Physiol 107 687-694... 

Streb, P., Feierabend, J., Bligny, R. 1997. Resistance to photoinhibition of photosystem II and catalase and antioxidative protection in high mountain plants. Plant Cell Environ., 20 1030-1040. 

Kirilovsky D, Vernotte C, Astier C et al. Reversible and irreversible photoinhibition in herbicide-resistant mutants of Synechocystis 6714. Biochim Biophys Acta 1988 933 124-131. 

In many cases, mutants of weed species with target-site resistance to triazines showed lower growth rate and ecological fitness than the susceptible wild type, when analyzed in absence of a triazine herbicide as selection agent. The quantum yield of CO2 reduction in resistant biotypes was decreased. Furthermore, the electron transfer between the primary and secondary quinones in the PS II reaction center was slowed, which may have been the cause of increased susceptibility to photoinhibition in the resistant biotypes [23, 24]. 

In spite of low-temperature-grown plants being chronically photoinhibited, these plants were more resistant to induced photoinhibition, i.e. Fy was quenched about 5-15% less than in high-temperature-grown plants (Fig. 6), over a range of leaf... 

To investigate whether there was any molecular modification of the PSII reaction centre of the R2K1 mutant that made it more resistant intrinsically to photoinhibition we performed photoinhibition experiments in the presence of streptomycin to inhibit all recovery from photoinhibition. The increase of susceptibility to photoinhibition was observed and all three strains showed similar sensitivities (data not shown). 

To induce photoinhibition of photosynthesis cold hardened and non hardened winter rye, spring barley and Scots pine were exposed to a stepwise increase of the PPFD at 5 (Rgure 1 A>D). Fully expanded, secondary leaves of rye and barley developed under the two growth regimes were used. For pine both primary and secondary needles were considered. It appears that leaves of winter rye developed at 5 had acquired an increased resistance to photoinhibition, whereas neither spring barley nor Scots pine did show any significant increase in resistance to photoinhibition upon cold acclimation. 

Primary winter rye leaves developed at a day/night temperature regime of 25/15 and then transferred to the low temperature of 5 for cold acclimation did not increase their resistance to photoinhibition (data not shown). In fact longer periods (more than one week) of cold acclimation of such leaves induced chlorosis demonstrating the limited ability of rye leaves to acclimate to low temperature when developed at high temperatures. 

We conclude that cold acclimation of winter rye increases its resistance to photoinhibition, whereas spring barley and Scots pine have the same susceptibilities to... 

Furthermore, leaves of winter rye have to develop at low temperatures in order to acquire increased resistance to photoinhibition. However, spinach, which has a very much bwer frost tolerance than winter rye, is reported to acquire increased resistance to photoinhibition during cold acclimation (4). Whether the different results obtained with winter rye and spinach, with respect of cold hardening induced resistance to photoinhibition, depend on different developmental strategies of the two species can not be said at present. In Chlamydomonas reinhardtii(5), however, an increased resistance to photoinhibition upon cold acclimation occurred in a culture of dividing and growing cells, which is a similar developmental strategy as that of winter rye. 

Low temperature has been shown to increase photoinhibidon under moderate to high light intensities (1). Even cold tolerant species can show photoinhibition if tiie light intensity or the duration of the treatment is sufficient (2). But cold hardening increases the resistance of certain species like spinach (3) or rye (ek uist and Huner, submitted) to photoinhibition under low temperature conditions. To further investigate the source of this increased resistance to photoinhibition in cold hardened rye, isolated cells have been submitted to photoinhibitory treatment and recovery. 

Previous results on intact rye leaves indicated that RH and RNH plants exhibited no photoinhibition after treatment at 20 C at 400 imol s (dquist and Huner, submitted). In addition, RH plants exhibited a significant resistance to photoinhibition at 5 C in contrast to RNH plants. The results for isolated RH and RNH indicated a similar susceptibility to photoinhibition at either 5 or 20 C. Fiutheimore, RH and RNH mesophyll cells did not exhibit a differential resistance to the photoinhibitoiy... 

This study shows that coincidence of freezing and high light produces photoinhibition of an over-wintering stand of the chilling resistant crop, B. napus. Photoinhibition is evident as a decrease in the quantum yield for CO2 assimilation. These decreases persist for 3-4 days when milder duller conditions occur. This contrasts to the... 

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