COMPARATIVE ANALYSES OF PHOTOSYNTHETIC PARAMETERS AND AGPase ACTIVITY OF WILD TYPE AND TRANSGENIC Oryza sativa L. PLANTS

Abstract

In the current study, we aim to determine the photosynthetic activity of transgenic rice which have different ADP-glucose pyrophosphorylase (AGPase) mutations and wild rice plants (Oryza sativa L.) and comparative analysis of amount of pigment and AGPase enzyme activity. Wild type and transgenic rice plants which have IV, QC and IVQC mutations which containing different amino acid content with the AGPase large subunits were grown in the climate chambers adjusted to long day conditions. Chlorophyll fluorescence measurements and photosynthesis capacity calculations were performed on live leaves of mutant and wild rice plants by using portable photosynthesis device. Chlorophyll a, chlorophyll b, chlorophyll a/b and total chlorophyll content were calculated and the comparison of starch quantities was obtained by using starch iodine staining method. In addition, AGPase kinetic parameters in the leaves were determined by enzyme kinetic characterization. Chlorophyll pigment analysis showed no significant difference in chlorophyll a, chlorophyll b, chlorophyll a/b and total chlorophyll contents of leaves and in photosynthetic fluorescence measurements in wild and transgenic plants. However, the partially purified QC mutant AGPase enzymes in AGPase kinetic characterization showed higher binding affinity to ATP and G1P substrates than wild-type and other mutant AGPase enzymes. In the iodine staining method, the QC mutant plant leaves were assigned wild type and higher amount of starch than the other mutants. As a result; the AGPase structure of the QC mutant transgenic rice plants exhibited a more stable character and increased starch starch content. It is thought that these data will shed light on the physiological and morphological studies of the third generation transgenic plants to be obtained in the future.