Chloroplast retrograde signalling is ultimately dependent on the
function of the photosynthetic light reactions and not only
guides the acclimation of the photosynthetic apparatus to
changing environmental and metabolic cues, but has a much
wider influence on the growth and development of plants. New
information generated during the past few years about
regulation of photosynthetic light reactions and identification of
the underlying regulatory proteins has paved the way towards
better understanding of the signalling molecules produced in
chloroplasts upon changes in the environment. Likewise, the
availability of various mutants lacking regulatory functions has
made it possible to address the role of excitation energy
distribution and electron flow in the thylakoid membrane in
inducing the retrograde signals from chloroplasts to the
nucleus. Such signalling molecules also induce and interact
with hormonal signalling cascades to provide comprehensive
information from chloroplasts to the nucleus.