PARENT SESSION
Posters P3B Photosynthetic acclimation: Ecophysiology, diverse environments. Abstracts (479-522)

Induction of C₄-photosynthesis enzymes in C₃-plants. Novruz Guliyev^*,1, Esmer Abdullaeva¹, Shahniyar Bayramov¹, Jalal Aliyev¹, ¹ Institute of Botany of Azerbaijan National Academy of Sciences, Baku, Azerbaijan

ABSTRACT- The activity of C₄-photosynthesis enzymes was found to be low in etiolated C₃-plants. After their illumination the activity of these enzymes was induced. Inhibitors of protein synthesis - cycloheximide and chloramphenicol - less or more influenced on induction of the C₄-photosynthesis enzymes by light. Water stress was determined to induce the activity of C4-photosynthesis enzymes in different wheat genotypes. In drought conditions the activity of C₄-photosynthesis enzymes increased both in leaves and ear elements of wheat genotypes. But this increase was more apparent in drought-tolerant genotypes. The activity of C₄-photosynthesis enzymes of wheat seedlings grown in chamber also increased but this increase was insignificant in comparison with one in the more mature plants grown under field conditions. The increase of C₄-photosynthesis enzyme activities in different wheat genotypes under drought conditions strengthens organic dicarbonic acid synthesis, increases CO₂ concentration in carboxylating center and thus partially prevents the decrease of the photosynthetic carbon assimilation. The activity of PEPC and NAD-MDH increased under water stress more than the others that confirm a significant role of these enzymes in formation of the dicarbonic acid during drought. NAD-MDH activity in C₃-plants was always many times higher than the activity of NADP-MDH. The effect of light, different temperature and effectors on activity of C₄-photosynthesis enzymes in vitro was also studied. It was found that the NADP-MDH to be induced by light more than the other enzymes. PEPC was more sensitive to high temperature than the other C₄-photosynthesis enzymes. The study of effectors that influence on PEPC activity of leaves and ear elements of wheat shows that grain enzyme was more similar to PEPC from C₄-plants. A moderate salt stress was also determined to cause an increase of the activity of some C₄-photosynthesis enzymes in C₃-plants. The results obtained prove that C₄-photosynthesis enzymes in C₃-plants play a certain role in their adaptation to extreme conditions.

KEY WORDS: drought, adaptation, wheat genotypes, C₄-enzymes activity