Journal of Biotechnology & Biomaterials
Open Access

Abstract

Photosynthesis, the process through which plants convert solar energy to chemical energy by harvesting sunlight and transfer the excited energy from photosystems (PS) PSII and PSI, which are membrane protein complexes that helps in primary photochemical reactions. In general abiotic stress affects the plant photosynthesis particularly salinity stress. There are number of studies on salt effects on photosynthesis of prokaryotic and eukaryotic species which were short term treatment of different concentrations of salt. Here we have grown the green algae C.reinhardtii cells directly in the medium containing NaCl with different concentrations (50 mM, 100mM, and 150mM) which is more close to the natural condition. The impact of high salt concentrations on the structural organization of photosynthetic apparatus in C.reinhardtii was studied. Confocal microscopy data have revealed the morphology of the cells indicating that salt stress had delayed the cell division. Electron transport processes were investigated using OJIP curves which reveals that both donor and acceptor side of PSII were impaired at moderate concentrations of NaCl (100,150 mM).The chlorophyll a emission peak in low temperature fluorescence measurements (77K) was reduced in increasing salt stress grown cells indicating that structural changes at the level of PSII and PSI had occurred. Further, circular dichroism (CD) spectrum in the visible region associated with the strongly coupled chlorophyll dimers showed reduction in intensity, indicating that pigment?pigment interactions were altered. Thylakoid protein complexes have been characterized using BN PAGE where many of the protein complexes were down regulated in high salt conditions indicating that protein-protein and pigment-protein interactions have changed. Further, western blot analysis of thylakoids with PSII core and light harvesting complex antibodies have shown that antenna proteins CP47, 43 along with Lhc components Lhcb1, Lhcb4 were reduced which indicates that both core and Lhc antenna are equally sensitive to the above optimum salt concentrations. This damage may be due to reactive oxygen species generated in chloroplast.

Biography

Satyabala Neelam completed her M.Tech in Biotechnology in the year 2009 from University of Hyderabad, Hyderabad, Andhra Pradesh. She is pursuing her Ph.D in Department of Biochemistry, under Dr. S. Rajagopal, Reader, Department of Plant sciences, University of Hyderabad, Hyderabad India.