Acclimation to excess light is required for optimizing plant performance under natural environment. The present work showed that the treatment of Arabidopsis leaves with exogenous H2O2 can increase the acclimation of PSII to excess light. Treatments with H2O2 also enhanced the capacity of the mitochondrial alternative respiratory pathway and salicylic acid (SA) content. Our work also showed that the lack in alternative oxidase (AOX1a) in AtAOX1a antisense line and the SA deficiency in NahG (salicylate hydroxylase gene) transgenic mutant attenuated the H2O2-induced acclimation of PSII to excess light. It indicates that the
H2O2-induced acclimation of PSII to excess light could be mediated by the alternative respiratory pathway and SA., Q. Z. Hou, Y. P. Wang, J. Y. Liang, L. Y. Jia, H. Q. Feng, J. Wen, N. Ehmet, J. Y. Bai., and Obsahuje bibliografii
We investigated the differential expression of AOX1 multi-gene family and the regulation of alternative respiratory pathway during initial greening development in leaves of rice (Oryza sativa L.) seedlings. After exposing the dark-grown rice seedlings to continuous irradiation, total respiration (Vt), capacity of alternative pathway (Valt), and their ratio (Valt/Vt) increased with the greening of leaves. In this process, AOX1c transcript increased under constant irradiation, while AOX1a and AOX1b transcripts were hardly detected. Thus AOX1c in rice presents a similar expression pattern as AOX2 does in many dicotyledonous species during greening development. Compared with the rapid increase of cyanideresistant respiration in the presence of photon energy, CO2 fixation was not observed until 8 h after the onset of irradiation. The AOX inhibitor salicylhydroxamic acid (SHAM; 1 mM) inhibited 67.3 % of cyanide-insensitive oxygen uptake in dark-grown leaves and 69.4 % of it in leaves grown under irradiation. Dark-grown plants pre-treated with SHAM were then irradiated for 12 h. SHAM did not obviously modify photosynthetic CO2 fixation rate on a chlorophyll (Chl) content basis in both leaves and simultaneously isolated chloroplasts. Hence during initial greening steps of the plants, the induction of alternative pathway and AOX1 expression by irradiation is not directly linked with carbon assimilation of photosynthesis. The application of SHAM partially limited Chl production in rapidly greening leaves, indicating that Chl synthesis in the process of greening might be medicated to some extent by alternative respiratory pathway. and H. Q. Feng ... [et al.].
The present work showed that spider mite-infested leaves placed in the light were more attractive to predatory mites than the infested leaves placed in the dark; furthermore, an increase in the light intensity enhanced this attractiveness. However, the increase of the light intensity did not change the attractiveness of the uninfested leaves to predatory mites. The capacity of cyanide-resistant respiration and the photosynthetic rates of both the infested and uninfested leaves increased with increasing light intensities, whereas the photosystem (PS) II chlorophyll (Chl) fluorescence decreased. The increase of the capacity of cyanide-resistant respiration in the infested leaves was more dramatic than that in the uninfested leaves, whereas the values of photosynthetic rates and Chl fluorescence were lower in the infested leaves than those in the uninfested leaves. Treatment of the infested and uninfested leaves with 1 mM salicylhydroxamic acid (SHAM, an inhibitor of cyanide-resistant respiration) decreased photosynthetic rates and caused further reductions in PSII fluorescence, especially under a higher light intensity. In contrast, the effects of SHAM on PSII fluorescence parameters and photosynthetic rates of the infested leaves were more dramatic than on those of the uninfested leaves. The treatment with SHAM did not significantly change the attractiveness of the infested or uninfested leaves to the predatory mites under all of the light intensities tested. These results indicated that cyanide-resistant respiration was not directly associated with the light-induced attraction of predators to plants, but it could play a role in the protection of photosynthesis. Such role might become relatively more important when photosynthesis is impaired by herbivores infestation. and H. Q. Feng ... [et al.].