The Possible Relationship between Ethylene and Polyamine Metabolism during the Flower Opening and Senescence, and their Effect on Flower Longevity in Hibiscus syriacus L.

Abstract

In the higher plants, S-adenosylmethionine (SAM) synthesized from methionine serves as a common substrate for the biosynthesis of ethylene and polyamine. To clarify the relationship of ethylene and polyamine metabolism during the anthesis and senescence of Hibiscus syriacus L. flowers, ethylene production and changes in the concentration of 1-aminocyclopropane-1-carboxylic acid (ACC), ACC-conjugate, and polyamines in the petal were examined. A very low level of ACC was detected in the petal, and a very low ethylene evolution was observed, even before flower opening. Ethylene production greatly increased just around the beginning of petal in-rolling and paralleled an increase of ACC-conjugate in the petal. With regard to polyamine concentration, spermine decreased with petal senescence in contrast to the sharp rise in ethylene production. Aminoethoxyvinylglycine, which is a potent inhibitor of ACC synthesis from SAM and thereby represses ethylene formation, extended the flower longevity and maintained a high spermine concentration in the petal. In contrast, methylglyoxal-bis (guanylhydrazone), which is a potent inhibitor of SAM decarboxylation and also inhibits spermine biosynthesis, promoted ethylene production and shortened the flower longevity. These findings suggest that a competition for SAM between ethylene and polyamine biosynthesis may play a key role in determining flower longevity in H. syriacus L.

Effects of various chemical agents and early ethylene production on floral senescence of Hibiscus syriacus L.

“…Difluoromethylornithine (DFMO) and cyclohexylamine (CHA), an inhibitor of PUT and SPD, had no effects on flower longevity. The promotion of senescence by SPM and MGBG treated before full bloom was also observed with the rise in endogenous ethylene production in our previous study (Seo et al 2007a). Polyamines had no effect on the retardation of senescence, and their biosynthesis inhibitors did not affect flower senescence, with the exception of MGBG.…”

“…Furthermore, AVG, which is a potent inhibitor of ACC synthesis and greatly represses ethylene formation, extended the flower longevity. In our previous study, we observed that ethylene production sharply increased with flower senescence and that treatment with ACC and ethephon promoted ethylene production and shortened flower longevity, while AVG strikingly retarded flower life (Seo et al 2007a). Clearly, ethylene plays a key role in determining flower longevity in the H. syriacus L. flower.…”

“…syriacus L. is very sensitive to ethylene and flower senescence is closely related to its production (Seo et al 2007a). Then, we examined ethylene production during flower opening by SPM, MGBG and CHI treatments that had been promoted flower senescence (Fig.…”

“…However, there have been few physiological and biochemical studies on the senescence process of this ephemeral flower compared with those on the vase-life of various cut flowers. There have been reports on the metabolism of ethylene and polyamines during flower senescence (Chae et al 1995;Seo et al 2007a) and changes in polyamine and ACC concentration in floral organs (Seo et al 2007b). Some studies of ephemeral flowers have also suggested that the action of ethylene to initiate senescence in these flowers differs from that in carnation, which have a long flower life (Woodson et al 1985).…”

“…Furthermore, their biosynthesis is closely linked to ethylene through the common precursor, S-adenosyl-L-methionine (SAM) (Kushad and Dumbroff 1991;Pandey et al 2000). It has been reported that polyamine application both extends (Lee et al 1997;Wang and Baker 1980) and shortens flower longevity (Downs and Lovell 1986;Seo et al 2007a).…”