Year: 2022

ANCIENT PROCESS. "It is not surprising that plants have evolved mechanisms for dealing with obsolete organ systems. The shedding of leaves by the process of abscission is a very ancient trait - fossils from as early as the Devonian period (i.e., -400 million years ago) show evidence of abscission scars." https://lnkd.in/dNWP3KD View in LinkedIn

SENESCENCE SYNDROME. "However, photosynthetic organs are rich in nutrients, which would be lost without mechanisms that salvage them before the obsolete organs are cast off. We refer to this salvage process as the senescence syndrome." https://lnkd.in/dNWP3KD View in LinkedIn

SOMATIC DECLINE. "After fertilization and as the seeds mature, the somatic tissues of the plant become increasingly senescent. However, if reproduction is delayed, anatomically definable vegetative meristems can initiate in axils of older leaves." https://lnkd.in/dNWP3KD View in LinkedIn

REDIRECTED ENERGY. "In theory, the progressive senescence of existing somatic tissues reflects the minimum energy spent on maintenance of these tissues - energy that is thus available for seed development." https://lnkd.in/dNWP3KD View in LinkedIn

PLUNDERING THE LEAF SOURCES. ">50% of the protein and 70% of the lipid is associated with the chloroplasts.Consequently, the initial stages of the senescence syndrome involve a breakdown of membrane structure within the chloroplast." https://lnkd.in/dNWP3KD View in LinkedIn

SPARED UNTIL LAST. "Autolytic changes in the cell do not extend injtially to the mitochondria or nucleus, both of which remain unaffected until very late in the process of senescence." https://lnkd.in/dNWP3KD View in LinkedIn

NET LOSS. "The loss of macromolecular constituents during plant tissue senescence is not associated with a concomitant rise in metabolite levels but rather with a decline in total carbon and nitrogen within the tissue. Indeed, the implied transport of metabolites out of the leaf has been substantiated in a number of cases." https://lnkd.in/dNWP3KD View in LinkedIn

SELF-SACRIFICE. "In this sense, the senescing leaf continues to function as a source of nutrients to the whole plant, but only at the expense of its own ability to survive." https://lnkd.in/dNWP3KD View in LinkedIn

DISMEMBERING TEAM. "The hydrolysis of proteins and nucleic acids that accompanies senescence must be mediated by proteases and nucleases, respectively. Transaminases may function to shunt nitrogen into the most common mobile forms, glutamine and asparagine, and mobilization of lipids released from thylakoid membranes presumably requires conversion to sugars through the glyoxylate cycle." https://lnkd.in/dNWP3KD View in LinkedIn

GENE DRIVEN. "It is clear that the senescence syndrome is a genetically controlled process that requires continuing gene expression." https://lnkd.in/dNWP3KD View in LinkedIn