Role of polyamines and ethylene as modulators of plant senescence

Abstract

Under optimal conditions of growth, senescence, a terminal phase of development, sets in after a certain physiological age. It is a dynamic and closely regulated developmental process which involves an array of changes at both physiological and biochemical levels including gene expression. A large number of biotic and abiotic factors accelerate the process. Convincing evidence suggests the involvement of polyamines (PAs) and ethylene in this process. Although the biosynthetic pathways of both PAs and ethylene are interrelated, S-adenosylmethionine (SAM) being a common precursor, their physiological functions are distinct and at times antagonistic, particularly during leaf and flower senescence and also during fruit ripening. This provides an effective means for regulation of their biosynthesis and also to understand the mechanism by which the balance between the two can be established for manipulating the senescence process. The present article deals with current advances in the knowledge of the interrelationship between ethylene and PAs during senescence which may open up new vistas of investigation for the future.

Relationships between polyamines, ethylene, osmoprotectants and antioxidant enzymes activities in wheat seedlings after short-term PEG- and NaCl-induced stresses

“…This correlation represents a feedback of the inhibition of the enzyme action in one pathway and of enzyme activation in the other pathway (Pandey et al 2000). Ethylene inhibited the activities of arginine decarboxylase and SAM decarboxylase thus reducing PAs contents (Bouchereau et al 1999).…”

The physiological, transcriptional and genetic responses of an ozone- sensitive and an ozone tolerant poplar and selected extremes of their F 2 progeny

“…S-adenosyl methionine (SAM) is the precursor molecule to both polyamines and ethylene (Langebartels et al, 1991;Pandey et al, 2000), both of which are thought to be involved in the response to ozone (Langebartels et al, 1991;Overmyer et al, 2005). It is of interest, therefore, that SAM Synthetase (SAMS) co-located to QTL for both late and early season visible damage on LG II.…”

“…It is of interest, therefore, that SAM Synthetase (SAMS) co-located to QTL for both late and early season visible damage on LG II. Pandey et al (2000) put forward a hypothesis for the interacting role of polyamines and ethylene in the control of senescence, with ethylene acting as a positive regulator and polyamines as a negative regulator. The authors suggested a model in which polyamine and ethylene biosynthetic pathways Table 5 50 most significant differentially expressed genes in common to P. deltoides and P. trichocarpa after exposure to 9 hrs 200 nL L À1 ozone.…”

Flowering and Production Improvement Studies of Mango cv. Banganpalli in Relation to Plant Growth Regulators and Chemicals

“…Polyamines form a class of aliphatic amines that are ubiquitous in living organisms and are known to have role in a wide range of biological processes including plant growth and development (Pandey et al, 2000). Putrescine, spermidine and spermine are the major forms of polyamines which are biosynthesised from orginine or ornithine.…”