The cyanobacterium Synechocystis sp. PCC 6803 carries out oxygenic photosynthesis analogous to higher plants. Its photosystem I contains seven different polypeptide subunits. The cartridge mutagenesis technique was used to inactivate the psaD gene which encodes subunit II of photosystem I. A mutant strain lacking subunit II was generated by transforming wild type cells with cloned DNA in which ...

In green plant-like photosynthesis, oxygen evolution is catalyzed by a thylakoid membrane-bound protein complex, photosystem II. Cytochrome b559, a protein component of the reaction center of this complex, is absent in a genetically engineered mutant of the cyanobacterium, Synechocystis 6803 [Pakrasi, H.B., Williams, J.G.K., and Arntzen, C.J. (1988). EMBO J. 7, 325-332]. In this mutant, the gen...

Pineapple (Ananas comosus) is a horticultural species of the Bromeliaceae family high socioeconomic interest, widely cultivated around world. The multiplication pineapple seedlings in field can be time-consuming, requiring significant labor investment. objective this study was to evaluate performance continuous and temporary immersion systems micropropagation scale-up species. Shoots were obtai...

Radix Isatidis (Isatis indigotica Fort.) is one of the most important traditional Chinese medicine plants. However, there is no suitable herbicide used for weed control in Radix Isatidis field during postemergence stage. To explore the safety of sulfonylurea herbicide nicosulfuron on Radix Isatidis (Isatis indigotica Fort.) seedlings and the photosynthetic physiological response of the plant to...

Basil (Ocimum basilicum L.) is one of the most important medicinal and aromatic plants. Light intensity an indispensable factor for plants due to its effect on photosynthesis physiological processes. Here, we investigated impact light intensities harvesting times green purple basil. The experiment involved subjecting three different levels sunlight 12 days: complete—100%, 50%, 30%—sunlight. In ...

Cucumber is generally a thermophilic species; however, cultivars have been selected for higher yield during winter cultivation in unheated glasshouses in temperate regions. We tested whether photosynthesis in these varieties had greater chilling tolerance. There was no difference in the instantaneous reduction of photosynthesis at low temperature between four winter glasshouse and four summer f...

In this research, twenty-two selected almond hybrids with their parents ‘A1-99’ (drought-sensitive) and ‘Tuono’ (relatively tolerant against drought), were investigated for screening drought tolerance using some morphological and physiological traits. This research was carried out in a complete randomized design with three replications at the Temperate Fruit Research Center of Horticultural Sci...

I Summary During evolution, most genes of the cyanobacterial ancestor of plastids were transferred to the nuclear genome of the host cell (endosymbiosis). Consequently, to maintain the physiological properties of plastids, new regulatory elements and protein import machineries have evolved. For proper assembly of the photosystem II complex, whose core proteins are still plastid encoded, several...

(1) Thylakoids isolated from leaves of two salt-tolerant higher plant species were found to require high (greater than 250 mM) concentrations of C! for maximal rates of photosynthetic 02 evolution and maximum variable chlorophyll a fluorescence yield. These activities were also tolerant to extremely high (2-3 M) salt concentrations. Their pH dependence was markedly different in the absence and ...

The first step of photosynthesis in plants is the absorption of sunlight by pigments in the antenna complexes of photosystem II (PSII), followed by transfer of the nascent excitation energy to the reaction centers, where long-term storage as chemical energy is initiated. Quantum mechanical mechanisms must be invoked to explain the transport of excitation within individual antenna. However, it i...