Photosystem II photoinhibitionrepair
cycle, for example, has arisen vital in protecting also Photosystem I against light-induced damage.
Availability of highly sophisticated genetic, biochemical and biophysical tools has greatly expanded
the catalog of components that carry out photoprotective functions in plants. On thylakoid membranes,
these components encompass a network of overlapping systems that allow delicate regulation of linear
and cyclic electron transfer pathways, balancing of excitation energy distribution between the two
photosystems and dissipation of excess light energy in the antenna system as heat. An increasing number
of reports indicate that the above mentioned mechanisms also mediate important functions in the
regulation of biotic stress responses in plants. Particularly the handling of excitation energy in the light
harvesting II antenna complexes appears central to plant immunity signaling. Comprehensive understanding
of the underlying mechanisms and regulatory cross-talk, however, still remain elusive.