Frontiers in plant senescence research: from bench to bank

Abstract

Recent research on senescence in plants has focused on these two domains, that are (1) to make SENSE of senescence at the molecular levels, and based on the molecular findings, (2) to devise ways to inhibit or manipulate senescence for agricultural improvement; in other words, to translate laboratory bench findings to practical applications. And much progress has been made in the past several years. The purpose of this special issue is to review and update the most recent research developments in these frontiers. The visible sign of senescence in leaves and in some fruits is the breakdown of chlorophyll. The underlying biochemical and molecular mechanisms have been very actively investigated and significant progress has been made. Hortensteiner (2012) has now offered an update in this regard. Systems biology is a new holistic approach to many aspects of biomedical and biological processes including plant senescence, and Guo (2012) has summarized the most current understandings of leaf senescence resulting from the use of this approach. Epigenetics represents another most hot area in life science. Humbeck (2012) reviews the current evidence that leaf senescence is regulated through epigenetic processes. Thus, several epigenetic mutants were shown to exhibit a senescence phenotype and the processes to be involved include global chromatin structure changes, senescence-specific histone modifications and changes in DNA methylation. It is well known that senescence can be induced and regulated by an array of environmental cues (such as drought stress, darkness, and extreme temperatures) and endogenous factors (such as reproductive growth, plant growth regulators, and age). How these signals are perceived and transduced has remained as hot topics. Zhang and Zhou (2012) and Jibran et al. (2013) have brought us the recent advances in signal transduction and hormonal regulation integrated with developmental and stress signals. It should be noted that age-related changes or ARCs, has been used by gerontologists and other scientists for many years. In their review, Jibran et al. (2013) have defined ‘‘an ARC as any irreversible change that is strictly dependent on age and thus development’’ and based on several lines of evidence, have proposed that hormonally and environmentally induced leaf senescence processes depend on ARCs. This is an interesting yet debatable hypothesis. In addition to leaf senescence, significant progress has recently also been made in senescence of flowers and fruits. In her review on flower senescence, Rogers (2012) updates research in understanding environmental, developmental and hormonal signals that affect petal senescence. In S.-S. Gan (&) Departments of Horticulture, and Plant Breeding and Genetics, Cornell University, Ithaca, NY 14853, USA e-mail: SG288@cornell.edu