Senescence is a key process that underpins many important agronomic traits including yield outcomes and pre- and post-harvest quality.
Senescence is a highly regulated and organized process during which macromolecules of the mature green leaf are dismantled and remobilised
for further use by the plant, either for new growth or for deposition indeveloping seeds. Efficient senescence is essential for the overall success of the plant and its following generations; however, premature senescence, induced by stress, leads to reduced yield and quality of crop plants. Abiotic stress is estimated to be the primary cause of crop loss worldwide, with the potential to cause a reduction of more than 50% in the average yield of the main crops. In general, leaf senescence is characterized by the breakdown of macromolecules and the mobilization of nutrients out of the senescing tissues. The rapid loss of chlorophyll, the lowering of protein and RNA levels or the leakiness of the cell membranes are used as senescence markers. The selective activation of gene expression but also the decrease of certain RNAs and/or proteins is likely to initiate and regulate this process. Despite the importance of the senescence processes in plants, our knowledge on regulatory mechanisms of senescence is still poor.