Ecological Significance of the Interaction of Photosynthesis Light and Dark Processes

The kinetics of 14C incorporation into glycolate was studied after changing the export of photosynthetic products from the leaf. It has been shown that the ribulose-bisphosphate-oxygenase pathway of glycolate formation works in the stationary state of the plant. An excess of photosyntates or a decrease in the amount of light primary products, as well as nitrates in the leaves, immediately turns on the transketolase pathway of glycolate formation. In this case, part of the oxygen formed in the photochemical reactions of chloroplasts ceases to be released from the leaf. After oxygen receives an electron from ferredoxin in the electron transport chain of chloroplasts, it starts (through photorespiration) the formation of non-carbohydrate photosyntates and metabolic processes in the cytoplasm. It was concluded that the main function of photorespiration in the regulation of photosynthesis is maintaining a balance between light and dark processes of photosynthesis on change of living conditions.

Understanding source-sink interactions: Progress in model plants and translational research to crops

Agriculture is facing a massive increase in demand per hectare as a result of an ever-expanding population and environmental deterioration.While we have learned much about how environmental conditions and diseases impact crop yield,until recently considerably less was known concerning endogenous factors,including within-plant nutrient allocation.In this review,we discuss studies of source-sink interactions covering both fundamental research in model systems under controlled growth conditions and how the findings are being translated to crop plants in the field.In this respect we detail efforts aimed at improving and/or combining C3,C4,and CAM modes of photosynthesis,altering the chloroplastic electron transport chain,modulating photorespiration,adopting bacterial/algal carbon-concentrating mechanisms,and enhancing nitrogen-and water-use efficiencies.Moreover,we discuss how modulating TCA cycle activities and primary metabolism can result in increased rates of photosynthesis and outline the opportunities that evaluating natural variation in photosynthesis may afford.Although source,transport,and sink functions are all covered in this review,we focus on discussing source functions because the majority of research has been conducted in this field.Nevertheless,considerable recent evidence,alongside the evidence from classical studies,demonstrates that both transport and sink functions are also incredibly important determinants of yield.We thus describe recent evidence supporting this notion and suggest that future strategies for yield improvement should focus on combining improvements in each of these steps to approach yield optimization.

Forecasting of Asian dust storm that occurred on May 10-13, 2011, using an ensemble-based data assimilation system

An ensemble-based assimilation system that used the MASINGAR ink-2 （Model of Aerosol Species IN the Global AtmospheRe Mark 2） dust forecasting model and satellite-derived aerosol optical thickness （AOT） data. processed in the JAXA （Japan Aerospace Exploration Agency） Satellite Monitoring for Environmental Studies （JASMES） system with MODIS （Moderate Resolution Imaging Spectroradiometer） observations. was used to quantify the impact of assimilation on forecasts of a severe Asian dust storm during May 10-13. 2011. The modeled bidirectional reflectance function and observed vegetation index employed in JASMES enable AOT retrievals in areas of high surface reflectance, making JASMES effective for dust forecasting and early warning by enabling assimilations in dust storm source regions. Forecasts both with and without assimilation were validated using PM^0 observations from China, Korea, and Japan in the TEMM WG1 dataset. Only the forecast with assimilation successfully captured the contrast between the core and tail of the dust storm by increasing the AOT around the core by 70-150% and decreasing it around the tail by 20-30% in the 18-h forecast. The forecast with assimilation improved the agreement with observed PMlo concentrations, but the effect was limited at downwind sites in Korea and Japan because of the lack of observational constraints for a mis-forecasted dust storm due to cloud.