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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.

Show MeSH
The expression of ACS genes in wild-type and RiEIL tomato fruit during development and ripening. Expression of each ACS gene was measured by real-time quantitative RT-PCR analysis. The relative quantity of each ACS mRNA was expressed as a percentage of LeACS2 at 40 DAA. Vertical bars are the SE of three replications. In some cases, the bars are too small to see.
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fig4: The expression of ACS genes in wild-type and RiEIL tomato fruit during development and ripening. Expression of each ACS gene was measured by real-time quantitative RT-PCR analysis. The relative quantity of each ACS mRNA was expressed as a percentage of LeACS2 at 40 DAA. Vertical bars are the SE of three replications. In some cases, the bars are too small to see.

Mentions: In order to determine the ACS genes responsible for the increase in the ethylene production in transgenic fruit, real-time RT-PCR analysis was performed. Expression levels of LeACS1A and LeACS6 were relatively low in both wild-type and RiEIL-18 fruit (Fig. 4), in agreement with Barry et al. (2000) and Nakatsuka et al. (1998). In wild-type fruit, transcripts of LeACS2 and LeACS4 increased dramatically with a burst of ripening-associated ethylene production (Fig. 4). In transgenic fruit, LeACS2 and LeACS4 transcripts increased with the increase of ethylene production, although the levels were considerably lower than in wild-type fruit.


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)

The expression of ACS genes in wild-type and RiEIL tomato fruit during development and ripening. Expression of each ACS gene was measured by real-time quantitative RT-PCR analysis. The relative quantity of each ACS mRNA was expressed as a percentage of LeACS2 at 40 DAA. Vertical bars are the SE of three replications. In some cases, the bars are too small to see.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: The expression of ACS genes in wild-type and RiEIL tomato fruit during development and ripening. Expression of each ACS gene was measured by real-time quantitative RT-PCR analysis. The relative quantity of each ACS mRNA was expressed as a percentage of LeACS2 at 40 DAA. Vertical bars are the SE of three replications. In some cases, the bars are too small to see.
Mentions: In order to determine the ACS genes responsible for the increase in the ethylene production in transgenic fruit, real-time RT-PCR analysis was performed. Expression levels of LeACS1A and LeACS6 were relatively low in both wild-type and RiEIL-18 fruit (Fig. 4), in agreement with Barry et al. (2000) and Nakatsuka et al. (1998). In wild-type fruit, transcripts of LeACS2 and LeACS4 increased dramatically with a burst of ripening-associated ethylene production (Fig. 4). In transgenic fruit, LeACS2 and LeACS4 transcripts increased with the increase of ethylene production, although the levels were considerably lower than in wild-type fruit.

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