Comparison of leaf senescence regulation between distantly related plant species uncovers knowledge gaps and opportunities for plant improvement strategies

Abstract

Leaf senescence is a destructive process that allows the efficient recycling of nutrients from dying leaves to growing parts of the plant. It is the final stage of leaf development that can be induced in response to stress. This makes leaf senescence an adaptive process that is highly beneficial for whole plant survival under unpredictable environmental conditions. Thus, the manipulation of this process has the potential to improve crop plants to become more climate resilient. In this review we compare leaf senescence processes between distantly related species to identify knowledge gaps and opportunities for plant improvement strategies. We describe that main signalling pathways controlled by carbohydrates, reactive oxygen species and hormones are conserved. However, the role of ethylene in age-induced leaf senescence in cereals is obscure. Moreover, downstream senescence regulatory signalling events are largely unknown, and these may be considerably different between members of annual dicots and cereals. Because leaf senescence regulation is so intricately connected to basic metabolic and developmental processes, we propose to increase research efforts to discover natural variation in senescence regulation and pinpoint gene variants that are tried and tested in nature.