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

Yokotani N, Nakano R, Imanishi S, Nagata M, Inaba A, Kubo Y - J. Exp. Bot. (2009)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Biological Sciences, 7549-1 Yoshikawa, Kibichuo-cho, Okayama, 716-1241 Japan.

ABSTRACT
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.

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Changes in the rate of ethylene production in wild-type and RiEIL fruit. Tomato fruits were harvested 35 d after anthesis and continuously treated with (+) or without (–) 1-MCP. Vertical bars are the SE of three replications.
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fig5: Changes in the rate of ethylene production in wild-type and RiEIL fruit. Tomato fruits were harvested 35 d after anthesis and continuously treated with (+) or without (–) 1-MCP. Vertical bars are the SE of three replications.

Mentions: In order to confirm the independence of the increases in ethylene in transgenic fruit from the positive feedback system, 1-MCP was applied continuously to wild-type and transgenic fruit harvested at the mature green stage (35 DAA). Non-treated wild-type fruit exhibited a typical climacteric pattern in ethylene production during storage (Fig. 5). Interestingly, the pattern and level of ethylene production in non-treated transgenic fruit were almost the same as those in 1-MCP-treated transgenic and wild-type fruit. A similar result was obtained from another transgenic line, RiEIL-10 (Supplementary Fig. S1 at JXB online). Incomplete reduction of ripening ethylene by 1-MCP was also observed by Nakatsuka et al. (1998) and Hoeberichts et al. (2002) in wild-type fruit. In all non-treated transgenic and 1-MCP-treated wild-type and transgenic fruit, LeACS2 and LeACS4 transcripts were at trace levels at harvest but were detected at a certain increased level at the end of storage (Fig. 6).


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

Yokotani N, Nakano R, Imanishi S, Nagata M, Inaba A, Kubo Y - J. Exp. Bot. (2009)

Changes in the rate of ethylene production in wild-type and RiEIL fruit. Tomato fruits were harvested 35 d after anthesis and continuously treated with (+) or without (–) 1-MCP. Vertical bars are the SE of three replications.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724697&req=5

fig5: Changes in the rate of ethylene production in wild-type and RiEIL fruit. Tomato fruits were harvested 35 d after anthesis and continuously treated with (+) or without (–) 1-MCP. Vertical bars are the SE of three replications.
Mentions: In order to confirm the independence of the increases in ethylene in transgenic fruit from the positive feedback system, 1-MCP was applied continuously to wild-type and transgenic fruit harvested at the mature green stage (35 DAA). Non-treated wild-type fruit exhibited a typical climacteric pattern in ethylene production during storage (Fig. 5). Interestingly, the pattern and level of ethylene production in non-treated transgenic fruit were almost the same as those in 1-MCP-treated transgenic and wild-type fruit. A similar result was obtained from another transgenic line, RiEIL-10 (Supplementary Fig. S1 at JXB online). Incomplete reduction of ripening ethylene by 1-MCP was also observed by Nakatsuka et al. (1998) and Hoeberichts et al. (2002) in wild-type fruit. In all non-treated transgenic and 1-MCP-treated wild-type and transgenic fruit, LeACS2 and LeACS4 transcripts were at trace levels at harvest but were detected at a certain increased level at the end of storage (Fig. 6).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Biological Sciences, 7549-1 Yoshikawa, Kibichuo-cho, Okayama, 716-1241 Japan.

ABSTRACT
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.

Show MeSH