Programmed senescence of plant organs

Abstract

The senescence of plant organs associated with reproductive development has been studied extensively during the past century, and it has long been recognized that this type of death is internally programmed. The regulation of organ senescence as well as its biochemical and genetic determinants has been an historically rich area of research. Certain plant hormones have been implicated as regulators or modulators of organ senescence and many of the biochemical pathways associated with the senescence syndrome have been elucidated. The genetic basis of organ senescence has also been well established by the identification of mutations that impair the senescence program and recently, transgenic plants have been used to critically determine the role of specific enzymes and hormonal signals in mediating programmed senescence of plant organs. Here, we review the current understanding of the processes that regulate leaf, flower and fruit senescence, emphasizing the role that programmed organ senescence plays in the adaptive fitness of plants.

A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera

“…However, the 33-kD cysteine proteinase could be involved in the programmed cell death (PCD) response. Cysteine proteinases are expressed during PCD in plants (Beers, 1997;Hadfield and Bennett, 1997;Mittler et al, 1997;Morel and Dangl, 1997;Pennell and Lamb, 1997;Buckner et al, 1998;Groover and Jones, 1999), but those cysteine proteinases differ from the caspases that trigger PCD in animals (Buckner et al, 1998). No plant analogs of the caspases have been identified (Buckner et al, 1998), and it is not known if the cysteine proteinases synthesized by plants during PCD "regulate" or "execute" cell death (Groover and Jones, 1999).…”

The hypersensitive response and the induction of cell death in plants

“…In plants, cell death is also invoked developmentally during xylogenesis, senescence, and reproduction (Hatfield and Bennett, 1997;Fukuda, 1997;Greenberg, 1996;Jones and Dangl, 1996). Here we will address the following key questions:…”

Approches génétiques de la mort cellulaire programmée : succès et questions

“…Ceux-ci peuvent être identifiés dans des organismes différents des animaux (plantes, champignons, Dictyostelium) et les résultats peuvent être extrapolés aux animaux s'il y a conservation phylogénétique. La mort cellulaire chez les plantes suscite maintenant beaucoup d'intérêt [47][48][49][50][51], en particulier pour des raisons agro-économiques. Les molécules caractérisées interviennent surtout dans les voies de signalisation induites lors de la réaction d'hypersensibilité à des pathogènes, et liées à des gènes de résistance [52][53][54], et elles concernent moins les mécanismes de la mort proprement dite, mais cette situation peut évoluer très vite.…”