Ripening-associated ethylene biosynthesis in tomato fruit is autocatalytically and developmentally regulated

Naoki Yokotani, Ryohei Nakano, Shunsuke Imanishi, Masayasu Nagata, Akitsugu Inaba, Yasutaka Kubo

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99 Citations (Scopus)


To investigate the regulatory mechanism(s) of ethylene biosynthesis in fruit, transgenic tomatoes with all known LeEIL genes suppressed were produced by RNA interference engineering. The transgenic tomato exhibited ethylene insensitivity phenotypes such as non-ripening and the lack of the triple response and petiole epinasty of seedlings even in the presence of exogenous ethylene. Transgenic fruit exhibited a low but consistent increase in ethylene production beyond 40 days after anthesis (DAA), with limited LeACS2 and LeACS4 expression. 1-Methylcyclopropene (1-MCP), a potent inhibitor of ethylene perception, failed to inhibit the limited increase in ethylene production and expression of the two 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) genes in the transgenic fruit. These results suggest that ripening-associated ethylene (system 2) in wild-type tomato fruit consists of two parts: a small part regulated by a developmental factor through the ethylene-independent expression of LeACS2 and LeACS4 and a large part regulated by an autocatalytic system due to the ethylene-dependent expression of the same genes. The results further suggest that basal ethylene (system 1) is less likely to be involved in the transition to system 2. Even if the effect of system 1 ethylene is eliminated, fruit can show a small increase in ethylene production due to unknown developmental factors. This increase would be enough for the stimulation of autocatalytic ethylene production, leading to fruit ripening.

Original languageEnglish
Pages (from-to)3433-3442
Number of pages10
JournalJournal of experimental botany
Issue number12
Publication statusPublished - Aug 2009


  • ACS
  • Ethylene
  • Fruit ripening
  • LeEIL
  • Tomato

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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