Suppression of Ca2+-Influx after ACC-uptake by spermine inVigna radiata

Abstract

Exogenous ACC-induced ethylene production in mung bean hypncotyl segments was severely inhibited by the treatment of spermine in a 6 hr incubation. In protoplasts acquired from the same tissues and pretreated with ACC, the concentration of cytosolic Ca 2~ was increased after the addition of exogenous Ca :+. However, this increase of Ca z+ concentration was strongly suppressed by spermine. In previous studies, an artifical increase of Ca 2+ influx by the treatment of a Ca2 § stimulated ACC-induced ethylene production. The inhibitory effect of spermine on ACC-induced ethylene production was more prominent than that of putrescine which has fewer NH ~ § groups than spermine. In addition, spermine more prominently suppressed ACC-induced ethylene production in protoplasts in which tewer Ca z~ ions were released from CaZ § organelles. Also, the amount of transcript of ACC-oxidase which converts ACC to ethylene was decreased by the treatment of spermine. However, this reduction resulted only through the suppression of ethylene production in a 2 hr incubation of mung bean segments. On the basis of these results, we suggest that there is a coupling of ACC-uptake to the increase of cylosolic Ca 2~ concentration. In addition, the reduction of exogenous ACC-induced ethylene production by spermine could have resulted, at least partially, from reducing the Ca 2~ influx which stimulates A('C-oxidase activity.

Effect of far infrared rays emitted from the calcined ceramics on ethylene production in mungbean hypocotyls

“…Woodson et al (1992) suggested that ACC oxidase activity increased in an autostimulatory manner in the carnation flower. In addition, Lee et al (1997) showed that ACCoxidase was increased by the promoted ethylene production between 60 min and 120 min in mungbean hypocotyl protoplasts. Therefore, further experiments are needed to focus on the regulation of ACC oxidase activity by far infrared ray at the molecular level.…”

“…Kim and Yang (1994) isolated 0.9 kb ACC-oxidase cDNA in mungbean hypocotyls. Using this cDNA, Lee et al (1997) showed regulation of the ACC-oxidase transcript by ethylene. They suggested that a latent period was required to increase the amount of ACC-oxidase transcript by the treatment of spermin, which inhibits ethylene production.…”