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Start Over Subject photosystem 1 and 2 activities

1. Effects of phytoplasma [stolbur-subgroup (Bois noir-BN)] on photosynthetic pigments, saccharides, ribulose 1,5-bisphosphate carboxylase, nitrate and nitrite reductases, and photosynthetic activities in field-grown grapevine (Vitis vinifera L. cv. Chardonnay) leaves

Creator:
Bertamini, M. and Nedunchezhian, N.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, chlorophyll, electron transport, donor side, and photosystem 1 and 2 activities
Language:
Multiple languages
Description:
In leaves of field-grown grapevine, the contents of chlorophyll, carotenoids, and soluble proteins and the activities of ribulose-1,5-bisphosphate carboxylase (RuBPC) and nitrate (NR) and nitrite (NiR) reductases were decreased in phytoplasma-infected leaves, but the contents of soluble sugars and total saccharides were markedly increased. In isolated thylakoids, phytoplasma caused marked inhibition of whole chain and photosystem 2 (PS2) activities. The artificial exogenous electron donor, diphenyl carbazide, significantly restored the loss of PS2 activity in infected leaves. and M. Bertamini, N. Nedunchezhian.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Photosynthetic electron transport, photophosphorylation, and antioxidants in two ecotypes of reed (Phragmites communis Trin.) from different habitats

Creator:
Zhu, X. Y., Chen, G. C., and Zhang, C. L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
antioxidant, ascorbate peroxidase, chloroplast, cyclic electron flow, Mg2+-ATPase, natural drought, photosystem 1 and 2 activities, stomatal resistance, superoxide dismutase, and transpiration rate
Language:
Multiple languages
Description:
We compared chloroplast photochemical properties and activities of some chloroplast-localised enzymes in two ecotypes of Phragmites communis, swamp reed (SR, C3-like) and dune reed (DR, C4-like) plants growing in the desert region of north-west China. Electron transport rates of whole electron transport chain and photosystem (PS) 2 were remarkably lower in DR chloroplasts. However, the electron transport rate for PS1 in DR chloroplasts was more than 90 % of the activity similar in the SR chloroplasts. Activities of Mg2+-ATPase and cyclic and non-cyclic photophosphorylations were higher in DR chloroplasts than in the SR ones. The activities of chloroplast superoxide dismutase (SOD) and ascorbate peroxidase (APX), both localised at or near the PS1 complex and serving to scavenge active oxygen around PS1, and the content of ascorbic acid, a special substrate of APX in chloroplast, were all higher in DR chloroplasts. Hence reed, a hydrophytic plant, when subjected to intense selection pressure in dune habitat, elevates its cyclic electron flow around PS1. In consequence, it provides extra ATP required by C4 photosynthesis. Combined high activities of active oxygen scavenging components in DR chloroplasts might improve protection of photosynthetic apparatus, especially PS1, from the damage of reactive oxygen species. This offers new explanation of photosynthetic performance of plant adaptation to long-term natural drought habitat, which is different from those, subjected to the short-term stress treatment or even to the artificial field drought. and X. Y. Zhu, G. C. Chen, C. L. Zhang.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Role of nitrate in photosynthetic electron transport of Chlorella vulgaris

Creator:
Osman, M. El-Anwar H. and El-Naggar, A. H.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chlorophyll fluorescence, DCMU, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, oxygen evolution rate, and photosystem 1 and 2 activities
Language:
Multiple languages
Description:
Addition of nitrate to a suspension of NO3--depleted Chlorella vulgaris cells raised the O2-evolving capacity of the organism by 60%. The rate of O2-evolution under flash irradiation of the depleted cells was drastically reduced, which could be restored by addition of NO3-. The 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB)-insensitive O2-evolution, i.e., photosystem (PS) 2 activity of NO3--depleted cells, showed a 75% stimulation by addition of NO3-. PS1-mediated electron transport was also stimulated (50%) by addition of NO3-. Fluorescence yields of the NO3--depleted cells were significantly reduced. A normal fluorescence response was restored by the addition of NO3-. The fluorescence yield of the NO3--depleted and DCMU-treated-cells increased significantly after addition of NO3- ions, indicating a further reduction of the primary acceptor of PS2 (Q). In addition, the low temperature fluorescence emission spectra showed that energy transfer to PS2 and PS1 was much higher when nitrate was present. Hence nitrate accelerates the light-induced charge transfer from the intact O2-evolving system to the primary electron acceptor of PS2 and stimulates the PS1-mediated electron transport. and M. El-Anwar H. Osman, A. H. El-Naggar.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public