Inhibition of quantum yield of PS II electron transport in Spirulina platensis by osmotic stress may be explained mainly by an increase in the proportion of the QB-non-reducing PS II reaction centres

Lu, Congming; Zhang, Jianhua; Vonshak, Avigad

doi:10.1071/pp98043

Cited by 15 publications

(7 citation statements)

References 20 publications

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“…Fluorescence can provide insights into the ability of a plant to tolerate environmental stresses and into the extent to which those stresses have damaged the photosynthetic apparatus (Fracheboud et al 1999;Maxwell and Johnson 2000). Previous studies showed that severe desiccation led to a decrease in F v /F m (Chen and Hsu 1995) and UPSII (Lu et al 1998). In this experiment, UPSII and F v /F m of treated ramets disconnected from untreated ramets decreased with increasing soil water contrast, which showed that drought stress may increase under high water contrast.…”

Section: Discussionmentioning

confidence: 50%

Photosynthetic response of Fragaria orientalis in different water contrast clonal integration

Zhang

Luo

et al. 2008

Ecological Research

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The capacity to exchange resources and nonresource agents is one of the most outstanding features of clonal plants. Contrast between patches in a heterogeneous environment is the main external driving force behind integration effects. It was hypothesized, on the basis of the source-sink hypothesis, that assimilate demand from drought-stressed ramets will result in enhancement of the photosynthesis of well-watered ramets by a mechanism of feedback regulation, that the negative effect of drought on the photosynthesis of drought-stressed ramets will be ameliorated by physiological integration, and that these effects will be enhanced by increasing contrast. A pot experiment was conducted with clonal fragments consisting of two interconnected ramets of Fragaria orientalis. In the experiment, both the connected and the disconnected clonal fragments were divided into three water contrast groups: (1) homogeneous (no contrast) group; (2) low-contrast group; (3) high-contrast group. The photosynthesis and stress tolerance of drought-stressed ramets did not decrease under the support of well-watered ramets when they were connected, allowing clones to maintain their performance in less favorable environments. But the photosynthesis and stress tolerance of drought-stressed ramets decreased with increasing drought-stress when stolons were disconnected. With a feedback regulation process, the photosynthesis of well-watered ramets connected to droughtstressed ramets was enhanced by the latter, which can compensate, at least partially, for the cost of maintaining the stressed ramets. Drought-stressed ramets gained more benefits in a high-contrast environment than in a lowercontrast environment; this can enhance the survival of drought-stressed ramets in unfavorable habitats, especially stressed patches that would otherwise be unexploitable by independent ramets. But photosynthesis of well-watered ramets did not increase with increasing water availability contrast. It can be concluded that photosynthesis and stress tolerance of F. orientalis was affected by clonal integration and by contrasts of water availability.

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Section: Discussionmentioning

confidence: 50%

Photosynthetic response of Fragaria orientalis in different water contrast clonal integration

Zhang

Luo

et al. 2008

Ecological Research

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“…Vonshak et al (1988Vonshak et al ( , 1995Vonshak et al ( , 1996, Zeng and Vonshak (1998), Lu et al (1998 and Vonshak (1999, 2002) have shown that an increase in salt concentration leads to the decrease of the specific growth rate, photosynthetic efficiency, maximum rate of photosynthesis, phycobilin/Chl a ratio and PSII activity. Conversely, dark respiration activity, compensation points and PSI activity are increased.…”

Section: Discussionmentioning

confidence: 96%

“…In particular, photosynthetic adaptation against salt stress seems to be associated with the modification of energy collector complexes, antennas, or reaction centers. These modifications occur essentially in PS II (Vonshak et al 1996;Lu et al 1998Vonshak 1999, 2002). According to , enhanced respiration rates induce a decrease of energy transfer between phycobilisomes and PSII.…”

mentioning

confidence: 99%

Growth, fluorescence, photosynthetic O2 production and pigment content of salt adapted cultures of Arthrospira (Spirulina) platensis

et al. 2007

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The effect of salt concentration (NaCl) on growth, fluorescence, photosynthetic activities and pigment content of the cyanobacterium Arthrospira platensis has been investigated over 15 days. It has been observed that high NaCl concentration induces an increase of the growth, photosynthetic efficiency (α), phycobilin/chlorophyll ratio and a slight decrease of dark respiration and compensation points. Moreover, high NaCl concentration enhances photosystem II (PSII) activity compared to photosystem I (PSI). Results show that the phycobilin-PSII energy transfer compared to the chlorophyll-PSII (F 695,600 /F 695,440 ) increases. However, data obtained about the maximal efficiency of PSII photochemistry are controversial. Indeed, the Fv/Fm ratio decreases in salt adapted cultures, while at the same time the trapping flux per PSII reaction center (TR 0 /RC) and the probability of electron transport beyond Q A (= 0 ) remain unchanged at the level of the donor and the acceptor sites of PSII. This effect can be attributed to the interference of phycobilin fluorescence with Chl a when performing polyphasic transient measurements.

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“…In the cyanobacterium Arthrospira, many studies have investigated the effects of salinity stress, osmotic stress, and photoinhibition on photosynthesis and PSII photochemistry (Lu et al 1998;Lu and Vonshak 1999a;Zhang et al 2010). However, how high temperature (heat stress) affects photosynthesis in Arthrospira, especially in marine Arthrospira, remains to be elucidated further.…”

Section: Introductionmentioning

confidence: 98%

Effects of heat stress on photosynthetic electron transport in a marine cyanobacterium Arthrospira sp.

Zhang

Liu

2015

J Appl Phycol

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Arthrospira (Spirulina) is widely used as human health food and animal feed. In cultures grown outdoors in open ponds, Arthrospira cells are subjected to various environmental stresses, such as high temperature. A better understanding of the effects of high temperature on photosynthesis may help optimize the productivity of Arthrospira cultures. In this study, the effects of heat stress on photosynthetic rate, chlorophyll a fluorescence transients, and photosystem (PS) II, PSI activities in a marine cyanobacterium Arthrospira sp. were examined. Arthrospira cells grown at 25°C were treated for 30 min at 25 (control), 30, 34, 37, or 40°C in the dark. Heat stress (30-37°C) enhanced net photosynthetic O 2 evolution rate. Heat stress caused over-reduction PSII acceptor side, damage of donor side of PSII, decrease in the energetic connectivity of PSII units, and decrease in the performance of PSII. When the temperature changed from 25 to 37°C, PSII activity decreased, while PSI activity increased, the enhancement of photosynthetic O 2 evolution was synchronized with the increase in PSI activity. When temperature was further increased to 40°C, it induced a decrease in photosynthetic O 2 evolution rate and a more severe decrease in PSII activity, but an increase in PSI activity. These results suggest that PSI activity was the decisive factor determining the change of photosynthetic O 2 evolution when Arthrospira was exposed to a temperature from 25 to 37°C, but then, PSII activity became the decisive factor adjusting the change of photosynthetic O 2 evolution when the temperature was increased to 40°C.

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Inhibition of quantum yield of PS II electron transport in Spirulina platensis by osmotic stress may be explained mainly by an increase in the proportion of the QB-non-reducing PS II reaction centres

Cited by 15 publications

References 20 publications

Photosynthetic response of Fragaria orientalis in different water contrast clonal integration

Photosynthetic response of Fragaria orientalis in different water contrast clonal integration

Growth, fluorescence, photosynthetic O2 production and pigment content of salt adapted cultures of Arthrospira (Spirulina) platensis

Effects of heat stress on photosynthetic electron transport in a marine cyanobacterium Arthrospira sp.

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