Dark-induced leaf senescence: new insights into a complex light-dependent regulatory pathway.

563 I. 563 II. 564 III. 564 IV. 565 V. 565 VI. 567 VII. 567 568 References 568 SUMMARY: Leaf senescence - the coordinated, active process leading to the organized dismantling of cellular components to remobilize resources - is a fundamental aspect of plant life. Its tight regulation is essential for plant fitness and has crucial implications for the optimization of plant productivity and storage properties. Various investigations have shown light deprivation and light perception via phytochromes as key elements modulating senescence. However, the signalling pathways linking light deprivation and actual senescence processes have long remained obscure. Recent analyses have demonstrated that PHYTOCHROME-INTERACTING FACTORS (PIFs) are major transcription factors orchestrating dark-induced senescence (DIS) by targeting chloroplast maintenance, chlorophyll metabolism, hormone signalling and production, and the expression of senescence master regulators, uncovering potential molecular links to the energy deprivation signalling pathway. PIF-dependent feed-forward regulatory modules might be of critical importance for the highly complex and initially light-reversible DIS induction.