Changes in the Activities of C4 Pathway Enzymes and Stable Carbon Isotope Discrimination in Flag Leaves of Super High-yield Hybrid Rice

Activities of several key enzymes of C-4 photosynthesis pathway and stable carbon isotope discrimination were investigated in flag leaves of a super high-yield hybrid rice (Oryza sativa L.) cv. Peiai 64S/E32 and a traditional hybrid rice cv. Shanyou 63 at different developing stages. Results show that the activity of PEP carboxylase (PEPCase) increased with age of flag leave; the activity of NADP-malate dehydrogenase (NADP-MDH) increased and reached to a peak value at grain filling stage (68-75 d after transplanting), then fell down; the activity of NADP-MDH in cv. Peiai 64S/E32 was much higher than that in cv. Shanyou 63. Before ripening stage (95 d after transplanting), NADP-malic enzyme activity rose gradually. The level of stable carbon isotope discrimination (Delta(13)C) in flag leaves and grains at different developing stages were similar and exhibited a comparative high value at ripening stage. The average Delta(13)C in leaf of cv. Peiai 64S/E32 during different developing stages was 0.43parts per thousand more than that in cv. Shanyou 63.

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.

002C-3 protects the brain against ischemia-reperfusion injury by inhibiting autophagy and stimulating CaMKK/CaMKIV/HDAC4 pathways in mice

This study was designed to investigate the effect of 002C-3, a derivative of magnolol, on transient cerebral middle occlusion （tMCAO） in a mice model and to identify the underlying mechanisms. 002C-3 （100 and 150 pg/kg, i.v. after ending occlusion） significantly reduced neurological deficit scores, infarct volumes, and brain water contents after 1.5 h MCAO and 24 h reperfusion. 002C-3 （75 150μg/kg） decreased the exudation of Evans blue from brain capillaries. 002C-3 （100 μg/kg） significantly inhibited the activity of MMP-9 and MMP-2 in the injured hemisphere. 002C-3 decreased the expression of autophagy-associated proteins, Beclin-1 and LC3B-Ⅱ, and increased the level of p62 in injured hemisphere. 002C-3 （100 pg/kg） significantly increased the expression of p-CaMKIV and p-HDAC4 in injured hemisphere. In conclusion, 002C-3 shows a neuroprotective effect on tMCAO injury in mice, and its mechanisms may be associated with alleviation of blood-brain barrier damage caused by the activation of MMPs, inhibition of autophagy, and stimulation of calcium signals related to cell survival. These findings suggest that 002C-3 is a neuroprotective agent that acts on multiple pathways.

Progress in the Breeding of Soybean for High Photosynthetic Efficiency

Studies for many years have indicated that the seed yield of (Glycine max L. Merr.) soybean can be increased by increasing photosynthetic efficiency. The yield of cultivars with high photosynthetic efficiency (HPE) increased by 30% - 40% in comparison with the cultivars with normal photosynthetic efficiency, indicating that the breeding of soybean by increasing RPE may have a bright prospect. HPE breeding can be used as the temporal monitoring in the breeding process to avoid the divergency of the predetermined goal, although HPE breeding does not shorten the breeding time. It was observed that limited C-4 pathway exists in soybean leaf and pod, suggesting that by increasing the genetic expression of some C-4 enzymes in C-3 crops through traditional or genetic engineering techniques, new breakthroughs in increasing the photosynthetic efficiency of C-3 plant may be practicable in the future.