Thermoluminescence in chloroplasts as an indicator of alterations in photosystem 2 reaction centre by biotic and abiotic stresses

Thermoluminescence (TL) in green plants arises from charge recombination of charged molecules in the reaction centre (RC) of photosystem 2 (PS2) in ch loroplasts. The TL technique is used for detection of alterations in the ar chitecture of PS2 RCs. The donor side 'S-states' and the acceptor side quin one Molecules (QA and QB) are involved the charge recombination processes o f PS2. High temperature (70-75 degreesC) glow peaks are also used to detect non-photo synthetic peroxidation processes in thylakoid membranes. The TL peaks with their characteristic charge recombination can be utilised for th e study of chloroplast development, ageing, chemical, biotic, and abiotic s tress induced alterations in the PS2 RC and for the study of the primary ph otochemical events of photosynthesis. The technique has been used successfu lly in the characterisation of transgenic plants in the study of geneticall y engineered organisms.