| Budget Amount *help |
¥3,810,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥510,000)
Fiscal Year 2007: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2006: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Ethylene is a key regulatory molecule for ripening and senescence and it is thought to regulate ripening of climacteric fruits. On the other hand, polyamines, mainly putrescine (Put), spermidine (Spd) and spermine (Spm), have also been implicated as having roles in fruit ripening and senescence. The interesting issue is the fact that polyamine and ethylene biosynthetic pathways are linked by sharing a common precursor S-adenosylmethionine (SAM). Therefore, the opposite physiological actions for polyamine and ethylene, inhibiting and promoting senescence, respectively, have been ascribed to the shifting demand for SAM.
Therefore, we investigated the effects of inhibition for ethylene pathway on the polyamine biosynthesis using 1-methylcyclopropene (1-MCP) in apple fruits ('Orin'). Furthermore, we studied the effects of inhibition for polyamine pathway on the ethylene production using methylglyoxal (bis-guanylhydrazone) (MGBG), a potent inhibitor for S-adenosylmethionine decarboxylase (SAMDC).
The results demonstrated a transient antagonistic relationship between polyamine and ethylene at the early stage after both 1-MCP and MGBG treatments ; induction of polyamine, especially Spd biosynthesis and enhanced production of ethylene were observed by 1-MCP and MGBG respectively. This, however, disappeared at the later stage possibly due to the polyamine homeostasis mechanism. Taken together with our results, the authors suggested that temporal antagonistic effect, which is induced by the response to the inhibitors, may be present in apple fruits, but such antagonistic effect disappeared with time after treatment, possibly due to the highly homeostatic regulation of both polyamine and ethylene pathways.
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