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Accueil du site → Master → Chine → 2021 → Studies on the Photosynthesis of Nostoc Flagelliforme (Cyanophyceae) Subjected to Desiccation and Rehydration and the Metabolism of Reactive Oxygen Specie

Central China Normal University (2021)

Studies on the Photosynthesis of Nostoc Flagelliforme (Cyanophyceae) Subjected to Desiccation and Rehydration and the Metabolism of Reactive Oxygen Specie

张爱红

Titre : Studies on the Photosynthesis of Nostoc Flagelliforme (Cyanophyceae) Subjected to Desiccation and Rehydration and the Metabolism of Reactive Oxygen Specie

Auteur : 张爱红

Grade : Master 2021

Université : Central China Normal University

Résumé partiel
Nostoc flagelliforme (Berk. & Curtis) Bornet & Flah. is an edible terrestrial blue-green alga with great economic value. It is distributed worldwide and in China mainly in the arid or semiarid areas of northern and west-northern parts. During the past twenty years, a number of studies have been carried out in China on the ecology, physiology, morphology, reproduction, culture and resources of N. jlagelliforme. Unfortunately its resources have been over-exploited due to the increasing market demands. Over-exploitation of this species has seriously damaged extensive ranges of vegetation in western and west-northern China. As a consequence, the State Council of the People’s Republic of China announced in June 2000 the prohibition of further collection and trading in N. flagelliforme, so as to halt the progress of desertification in northern China. Its protection degree has also been elevated to the first-rank.The metabolism of reactive oxygen species in N. flagelliforme and effects of exogenous oxidants on its photosynthetic recovery were investigated to obtain insight into oxidative stress in desiccation and its possible damaging impact on photosynthetic apparatus. No ascorbate acid was detected with ascorbate oxidase in N. flagelliforme. Superoxide dismutase (SOD) remained active even after 3 years of drying storage and its activity was 78% of that in fully recovered samples. The SOD activity decreased during desiccation or in drying storage. Intracellular active oxygen production was studied by incubating samples in BGu medium for 2 h and measuring the oxidation of 2’, 7’-dichlorohydrofluorescein diacetate. The production rate of DCF was 38.11 nmol DCF g (d.wt)-1h-1 in dried field samples and was significantly higher than in fully recovered samples or air-dried samples. The balance between intracellular active oxygen production and the defense system might break down in air-dried and dried field samples. Treatment with exogenous oxidants slowed the photosynthetic recovery especially with singlet oxygen. Oxidative stress might play an important role in desiccation-induced damages to the photosynthetic apparatus.The photosynthetic response of Nostoc flagelliforme to desiccation and rehydration was investigated in this paper.

Mots clés : blue-green alga ;chlorophyll fluorescence ;cyanobacterium;desiccation ;Nostoc flagelliforme ;photosynthesis;PS II activity ;reactive oxygen species ;rehydration;77K fluorescence ;

Présentation (CNKI)

Page publiée le 12 mars 2022