Senescing leaves possess potential for stress adaptation: the developing leaves acclimated to high light exhibit increased tolerance to osmotic stress during senescence.

Plants may experience environmental stress factors operating in nature either simultaneously or in sequence. In the study, we have acclimated the developing primary leaves of wheat seedlings to high light stress and examined their photosynthetic response to polyethylene glycol (PEG) mediated osmotic stress during different developmental phases including senescence. The high light acclimated leaves show higher level of total carotenoids as compared to their non-acclimated counterparts experiencing osmotic stress during senescence.

Topology and photoprotective role of carotenoids in photosystem II of chloroplast: a hypothesis.

On the basis of existing evidence, a model is proposed for the topology of carotenoids in photosystem II (PS II) of chloroplasts. suggesting their possible roles in the photoprotection and stability of PS II complex. The presence of one cis and one trans beta-carotene at reaction centre II (RC II), with different photoprotective functions, is suggested.