High growth temperatures and high soil nitrogen do not alter differences in CO assimilation between invasive Phalaris arundinacea (reed canarygrass) and Carex stricta (tussock sedge).

Premise Of The Study: Global change in temperature and soil nitrogen availability could affect plant community composition, potentially giving an advantage to invasive species compared to native species. We addressed how high temperatures affected CO assimilation parameters for invasive Phalaris arundinacea and a sedge, Carex stricta, it displaces, in natural and controlled environments.

Methods: Photosynthetic parameters were measured in a wetland in Indiana, USA during the abnormally warm year of 2012.

Constitutively overexpressing a tomato fructokinase gene (LeFRK1) in cotton (Gossypium hirsutum L. cv. Coker 312) positively affects plant vegetative growth, boll number and seed cotton yield.

Increasing fructokinase (FRK) activity in cotton (Gossypium hirsutum L.) plants may reduce fructose inhibition of sucrose synthase (Sus) and lead to improved fibre yield and quality. Cotton was transformed with a tomato (Solanum lycopersicum L.

Plasticity of nitrogen allocation in the leaves of the invasive wetland grass, Phalaris arundinacea and co-occurring Carex species determines the photosynthetic sensitivity to nitrogen availability.

Phalaris arundinacea displaces the slower-growing, native sedge, Carex stricta, where nitrogen availability is high. Our aim was to address whether morphological and physiological traits associated with carbon gain for P. arundinacea and C.

Expression of AtSAP5 in cotton up-regulates putative stress-responsive genes and improves the tolerance to rapidly developing water deficit and moderate heat stress.

The regulation of gene expression is a key factor in plant acclimation to stress, and it is thought that manipulation of the expression of critical stress-responsive genes should ultimately provide increased protection against abiotic stress. The aim of this study was to test the hypothesis that the ectopic expression of the AtSAP5 (AT3G12630) gene in transgenic cotton (Gossypium hirsutum, cv. Coker 312) will improve tolerance to drought and heat stress by up-regulating the expression of endogenous stress-responsive genes.

The differential response of photosynthesis to high temperature for a boreal and temperate Populus species relates to differences in Rubisco activation and Rubisco activase properties.

Significant inhibition of photosynthesis occurs at temperatures only a few degrees ( View Article and Find Full Text PDF

Soil bacteria augment Arabidopsis photosynthesis by decreasing glucose sensing and abscisic acid levels in planta.

Photosynthesis is regulated by environmental factors as well as endogenous sugar signals. Whereas light-driven sugar biosynthesis is essential for terrestrial organisms, as well as belowground microflora, whether and how soil symbionts regulate photosynthesis has yet to be reported. Here, we show that the plant growth-promoting soil bacterium Bacillus subtilis GB03 augments photosynthetic capacity by increasing photosynthetic efficiency and chlorophyll content in Arabidopsis.

The Arabidopsis ascorbate peroxidase 3 is a peroxisomal membrane-bound antioxidant enzyme and is dispensable for Arabidopsis growth and development.

Ascorbate peroxidase (APX) exists as several isoforms that are found in various compartments in plant cells. The cytosolic and chloroplast APXs appear to play important roles in antioxidation metabolism in plant cells, yet the function of peroxisomal APX is not well studied. In this study, the localization of a putative peroxisomal membrane-bound ascorbate peroxidase, APX3 from Arabidopsis, was confirmed by studying the green fluorescent protein (GFP)-APX3 fusion protein in transgenic plants.

The role of antioxidant enzymes in photoprotection.

The enzymatic component of the antioxidant system is discussed as one of the defensive mechanisms providing protection against excessive light absorption in plants. We present an analysis of attempts to improve stress tolerance by means of the creation of transgenic plants with elevated antioxidant enzyme activities and conclude that the effect of such transgenic manipulation strongly depends on the manner in which the stress is imposed. The following factors may diminish the differences in photosynthetic performance between transgenic plants and wild type under field conditions: effective functioning of the thermal dissipation mechanisms providing a primary line of defense against excessive light, long-term adjustments of the antioxidant system and other photoprotective mechanisms, the relatively low level of control over electron transport exerted by the Water-Water cycle, especially under warm conditions, and a decrease in the content of the transgenic product during leaf aging.

Compensation for PSII photoinactivation by regulated non-photochemical dissipation influences the impact of photoinactivation on electron transport and CO2 assimilation.

The extent to which PSII photoinactivation affects electron transport (PhiPSII) and CO2 assimilation remains controversial, in part because it frequently occurs alongside inactivation of other components of photosynthesis, such as PSI. By manipulating conditions (darkness versus low light) after a high light/low temperature treatment, we examined the influence of different levels of PSII inactivation at the same level of PSI inactivation on PhiPSII and CO2 assimilation for Arabidopsis. Furthermore, we compared PhiPSII at high light and optimum temperature for wild-type Arabidopsis and a mutant (npq4-1) with impaired capacities for energy dissipation.

Expression of an Arabidopsis vacuolar sodium/proton antiporter gene in cotton improves photosynthetic performance under salt conditions and increases fiber yield in the field.

Drought and salinity are two major limiting factors in crop productivity. One way to reduce crop loss caused by drought and salinity is to increase the solute concentration in the vacuoles of plant cells. The accumulation of sodium ions inside the vacuoles provides a 2-fold advantage: (i) reducing the toxic levels of sodium in cytosol; and (ii) increasing the vacuolar osmotic potential with the concomitant generation of a more negative water potential that favors water uptake by the cell and better tissue water retention under high soil salinity.

Long-term night chilling of cotton (Gossypium hirsutum) does not result in reduced CO assimilation.

The aim of this study was to characterise the response of CO assimilation (A) of cotton (Gossypium hirsutum L.) to short- and long-term exposures to night chilling. We hypothesised that short-term exposures to night chilling would induce reductions in g and, therefore, A during the following days, while growth of cotton plants for several weeks in cool night conditions would cause elevated leaf carbohydrate content, leading to the down-regulation of the capacity for A.

Overexpression of the Arabidopsis 14-3-3 protein GF14 lambda in cotton leads to a "stay-green" phenotype and improves stress tolerance under moderate drought conditions.

The Arabidopsis gene GF14 lambda that encodes a 14-3-3 protein was introduced into cotton plants to explore the physiological roles that GF14 lambda might play in plants. The expression level of GF14 lambda under the control of the cauliflower mosaic virus 35S promoter varied in transgenic cotton plants, and lines that expressed GF14 lambda demonstrated a "stay-green" phenotype and improved water-stress tolerance. These lines wilted less and maintained higher photosynthesis than segregated non-transgenic control plants under water-deficit conditions.

Predicting the extent of photosystem II photoinactivation using chlorophyll a fluorescence parameters measured during illumination.

The temperature dependence of the relationship between the decline in activity of photosystem II (PSII) and a chlorophyll a fluorescence parameter combining the excitation pressure (1-qP) and efficiency of excitation energy capture by open PSII reaction centers in the light-acclimated state (Fv'/Fm') was investigated in cotton leaves. A formula for the prediction of PSII inactivation is proposed on the basis of the results obtained. By comparison of the predicted and actual levels of PSII photoinactivation, the rate of PSII recovery was estimated from chlorophyll a fluorescence parameters measured during the day for attached cotton leaves exposed to suboptimal morning temperatures in a greenhouse.

Transgenic overproduction of glutathione reductase does not protect cotton, Gossypium hirsutum (Malvaceae), from photoinhibition during growth under chilling conditions.

In some studies, tissues from plants that have been genetically transformed to overproduce antioxidant enzymes sustain less damage when abruptly exposed to short-term chilling in the laboratory. However, few studies have examined the performance of transgenic plants during longer-term growth under chilling conditions. We compared growth of transgenic cotton that overproduces glutathione reductase (GR+; ∼40-fold overproduction) to growth of the wild type in a controlled environment chamber as leaf temperature was lowered from 28° to 14°C over 9 d and for a subsequent 9-d period at 14°C.

Elevated chloroplastic glutathione reductase activities decrease chilling-induced photoinhibition by increasing rates of photochemistry, but not thermal energy dissipation, in transgenic cotton.

The effect of the overproduction of glutathione reductase (GR+) in cotton (Gossypium hirsutum L. cv.Coker 312) chloroplasts on the response of photosynthetic parameters to chilling in the light was examined.

Enhanced photochemical light utilization and decreased chilling-induced photoinhibition of photosystem II in cotton overexpressing genes encoding chloroplast-targeted antioxidant enzymes.

The aim of this study was to determine whether increases in stromal superoxide dismutase (SOD; EC 1.15.1.