Effect of Soil Drought on C4 Photosynthetic Enzyme Activities of Flag Leaf and Ear in Wheat

The activities of RuBPC and C4 photosynthetic enzymes in ear and flag leaf blade were examined in wheat. The results showed that photosynthesis of ear was less sensitive to soil drought than that of flag leaf, and decrease of CO2 assimilation in flag leaf blade with water stress was more than that in ear. Compared with flag leaf, ear organs (awn, glume and lemma) had higher C4 enzyme activities and lower RuBPC activity. Under moderate water-stress, the increase of C4 enzyme activities was induced, and the increase was higher in ear than in flag leaf. Under severe water-stress, relatively higher C4 enzyme activities were still maintained in ear, rather than that in flag leaf. It suggests that high activities of C4 enzymes in ear may contribute to its high tolerance of photosynthesis to water-stress.

Species- and Habitat-variability of Photosynthesis, Transpiration and Water Use Efficiency of Different Plant Species in Maowusu Sand Area

Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in the Maowusu Sand Area were analyzed and the relation among these characteristics and the resource utilization efficiency, taxonomic categories and growth forms of the species were assessed. The results showed that species from Chenopodiaceae, Gramineae, Leguminosae which possessed the C 4 photosynthesis pathway, or C 3 pathway and also with nitrogen_fixation capacities had higher or the highest P n values, i.e., 20～30 μmol CO 2·m -2 ·s -1 , while that of evergreen shrub of Pinaceae had the lowest P n values, i.e., 0～5 μmol CO 2·m -2 ·s -1 . Those species from Compositae, Scrophulariaceae, and Gramineae with C 3 pathway but no N_fixation capacity had the highest E rates, i.e., 20～30 mmol H 2O·m -2 ·s -1 and again the evergreen shrub together with some species from Salicaceae and Compositae had the lowest E rates, i.e., 0～5 mmol H 2O·m -2 ·s -1 . Species from Leguminosae, Gramineae and Chenopodiaceae with C 4 pathway or C 3 pathway with N_fixation capacity, both shrubs and grasses, generally had higher WUE . However, even the physiological traits of the same species were habitat_ and season_specific. The values of both P n and E in late summer were much higher than those in early summer, with average increases of 26%, 40% respectively in the four habitats. WUE in late summer was, however, 12% lower. Generally, when the environments became drier as a result of habitats changed, i.e., in the order of wetland, lowland, fixed sand dune and shifting sand dune, P n and E decreased but WUE increased.

Activities of principal photosynthetic enzymes in green macroalga Ulva linza:functional implication of C_4 pathway in CO_2 assimilation

The green-tide-forming macroalga Ulva linza was profiled by transcriptome sequencing to ascertain whether the alga carries both C3 and C4 photosynthesis genes.The key enzymes involved in C4 metabolism including pyruvate orthophosphate dikinase(PPDK),phosphoenolpyruvate carboxylase(PEPC),and phosphoenolpyruvate carboxykinase(PCK) were found.When measured under normal and different stress conditions,expression of rbcL was higher under normal conditions and lower under the adverse conditions,whereas that of PPDK was higher under some adverse conditions,namely desiccation,high salinity,and low salinity.Both ribulose-1,5-biphosphate carboxylase(RuBPCase) and PPDK were found to play a role in carbon fixation,with significantly higher PPDK activity across the stress conditions.These results suggest that elevated PPDK activity alters carbon metabolism in U.linza leading to partial operation of the C4 carbon metabolism,a pathway that,under stress conditions,probably contributes to the hardy character of U.linza and thus to its wide distribution.

Hydrogen sulfide protects against high glucose-induced H9c2 cardiomyocyte injury and inflammatory response by inhibiting ROS-TLR4 pathway

Objective To investigate whether exogenous hydrogen sulfide（H2S）protects high glucose（HG）-inducedH9c2 cardiomyocyte injury and inflammation response by inhibiting reactive oxygen species（ROS）-Toll-like receptor 4（TLR4）pathway.Methods Cell counter kit-8（CCK-8）assay was used to measure the cell viability,