Ultraviolet-A induced changes in photosystem II of thylakoids: effects of senescence and high growth temperature
L Nayak1, B Biswal, N K Ramaswamy
1School of Life Sciences, Sambalpur University, Jyoti Vihar, Sambalpur, India.
Abstract:
Ultraviolet-A (UV-A) radiation induced changes in photosystem II (PS II) of senescing leaves of wheat seedlings were investigated. UV-A radiation did not show any significant effect on the level of photosynthetic pigments. However, the decline in F(v)/F(m) and oxygen evolution rate indicated the damaging effect of the radiation on primary photochemistry of PS II. Modification at the Q(B)-binding site was inferred from the observed downshift of peak temperature of thermoluminescence (TL) B-bands. The UV-A induced changes in PS II of chloroplasts from senescing leaves were found to be synergistically accelerated by high growth temperature.
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