Эволюционные аспекты формирования фотосинтеза
Aims. The photosynthesis evolution in connection with climate changes and CO2 content in Earth atmosphere in different geological periods and in last ages is considered. The C3–type of photosynthesis is more ancient and appeared in period of plant adaptation to life in land and genesis of vascular plants 300 million years ago. The large amount of modern plant species remained the C3–type of photosynthesis that was effective under low temperatures, humidity and illumination conditions. The C4–type of photosynthesis was formed under damp and hot climate and decreasing CO2 content in atmosphere. Methods. The leaves of this type plants have the specific type of structure and high effectiveness of photosynthetic processes under temperatures higher than 25–30 °C. Effectiveness of C3–type of photosynthesis under high temperature conditions decreases through shift of Rubisco from carboxylation to oxygenation reaction, enhancing photorespiration and CO2 losses. Results. The development of industrialization led to increasing of CO2 content in air that increased the rate of photosynthetic gaseous exchange, stimulated increase of plant weight, leaves square, quantity of mesophyll cells and chloroplasts in C3 and C4–plants. The relation of carboxylation and oxygenation of Rubisko reaction rates under constant gaze structure of atmosphere and temperature determined by specificity of species but could considerably fluctuate between under changes of relation CO2 / O2 and temperature in microspace.
Key words: photosynthesis, evolution, CO2 content, C3 and C4–plants.