Photosynthesis: Metabolic Transport and Cold Lability of Photosynthetic Enzymes

光合作用是一个重要的生物过程，了解其机制及其受植物内部和环境因素的控制非常重要。植物从大气中吸收二氧化碳，并将其同化为有机磷酸盐，用于合成淀粉、蔗糖、氨基酸等。有限数量的高等植物，包括玉米，已经进化出一种将二氧化碳集中在叶子中的机制，这样空气中的低浓度（0.034%）就不会限制它们进行光合作用的能力。这种机制涉及一种叫做c - 4循环的生化途径，这样的植物被称为c - 4植物。C . .植物在高温强光下的光合作用速率非常高。然而，在许多c4植物中，光合作用对中低温（即10至15℃）相当敏感。而少数物种或种族的耐受性更强。在这个项目中，将检查与C.4循环相关的过程（有机化合物的运输和蛋白质作为反应催化剂的功能）对低温的敏感性。在低温下保护过程的因素将在耐冷的C.4植物中进行研究。从这些研究中获得的基本知识将对开发C.4光合作用的机制有价值，从而可以更大规模地用于粮食生产、生物量和城市应用。

Photosynthesis is of fundamental importance as a biological process and it is important to understand its mechanism, and control by factors within the plant and in the environment. Plants take up carbon dioxide from the atmosphere and assimilate it into organic phosphates which are used for synthesizing starch, sucrose, amino acids, etc. A limited number of higher plants, including maize (corn), have evolved a mechanism for concentrating carbon dioxide in their leaves so that the low concentration in the air (0.034%) does not limit their ability to perform photosynthesis. This mechanism involves a biochemical pathway called the C.4 cycle, and such plants are called C.4 plants. C..4 plants achieve very high rates of photosynthesis under high temperature and light intensities. However, in many C.4 plants, photosynthesis is quite sensitive to moderately low temperatures (i.e. 10 to 15.oC while a few species or races are more tolerant. In this project, sensitivity to low temperature will be examined relative to processes associated with the C.4 cycle (transport of organic compounds and function of proteins as catalysts of reactions). Factors which protect the processes under low temperatures will be examined in C.4 plants which are chilling tolerant. Basic knowledge gained from these studies will be of value in exploiting the mechanism of C.4 photosythesis so that it can be used on a larger scale in production of food, biomass and in urban applications.