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Co-ordination of early and late ripening events in apples is regulated through differential sensitivities to ethylene.

Johnston JW, Gunaseelan K, Pidakala P, Wang M, Schaffer RJ - J. Exp. Bot. (2009)

Bottom Line: In this study, it is shown that anti-sense suppression of Malus domestica 1-AMINO-CYCLOPROPANE-CARBOXYLASE OXIDASE (MdACO1) resulted in fruit with an ethylene production sufficiently low to be able to assess ripening in the absence of ethylene.A sustained exposure to ethylene was required to maintain ripening, indicating that the role of ethylene may go beyond that of ripening initiation.These results suggest a conceptual model for the control of individual ripening characters in apple, based on both ethylene dependency and sensitivity.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute For Plant & Food Research Limited, Private Bag 92169, Auckland, New Zealand.

ABSTRACT
In this study, it is shown that anti-sense suppression of Malus domestica 1-AMINO-CYCLOPROPANE-CARBOXYLASE OXIDASE (MdACO1) resulted in fruit with an ethylene production sufficiently low to be able to assess ripening in the absence of ethylene. Exposure of these fruit to different concentrations of exogenous ethylene showed that flesh softening, volatile biosynthesis, and starch degradation, had differing ethylene sensitivity and dependency. Early ripening events such as the conversion of starch to sugars showed a low dependency for ethylene, but a high sensitivity to low concentrations of ethylene (0.01 microl l(-1)). By contrast, later ripening events such as flesh softening and ester volatile production showed a high dependency for ethylene but were less sensitive to low concentrations (needing 0.1 microl l(-1) for a response). A sustained exposure to ethylene was required to maintain ripening, indicating that the role of ethylene may go beyond that of ripening initiation. These results suggest a conceptual model for the control of individual ripening characters in apple, based on both ethylene dependency and sensitivity.

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Related in: MedlinePlus

Response curves of different ripening characters for MdACO1as fruit treated with different concentrations of ethylene. Flesh firmness (A) starch pattern index (B), skin background colour (C), soluble solids concentration (D), titratable acidity (E), total volatiles (F), and individual volatiles (G–L). Each point depicts the mean of 14 fruit.
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fig4: Response curves of different ripening characters for MdACO1as fruit treated with different concentrations of ethylene. Flesh firmness (A) starch pattern index (B), skin background colour (C), soluble solids concentration (D), titratable acidity (E), total volatiles (F), and individual volatiles (G–L). Each point depicts the mean of 14 fruit.

Mentions: To establish the level of ethylene needed to induce a ripening response, MdACO1as lines were exposed continuously to a range of ethylene concentrations from 0.01 to 1000 μl l−1 for 14 d at 20 °C. Ethylene response curves were then produced for the six main ripening traits and for the six dominant volatiles (Fig. 4). While there was no clear response to ethylene for titratable acidity and soluble solids concentration, distinct response curves were established for volatile production, firmness, skin background colour, and starch clearance. The general pattern for these curves was sigmoidal, with little or no change in ripening at low concentrations, followed by a rapid increase in response from 0.1 to 10 μl l−1, and little or no change thereafter at which point the process was saturated. However, there were subtle differences in the responses of individual ripening traits, where the majority of the response occurred between 0.1 and 10 μl l−1 for softening, background colour and total volatiles, while in contrast a lower range of 0.01 to 1 μl l−1 was required for starch clearance. Results from the 0.01 and 0.1 μl l−1 ethylene concentrations were indistinguishable from the no-ethylene treatment controls for volatiles, firmness, and background colour suggesting that these concentrations are below the response threshold for these processes. A small increase in starch degradation was observed for the 0.01 μl l−1 ethylene-treated fruit, suggesting a lower response threshold for this trait.


Co-ordination of early and late ripening events in apples is regulated through differential sensitivities to ethylene.

Johnston JW, Gunaseelan K, Pidakala P, Wang M, Schaffer RJ - J. Exp. Bot. (2009)

Response curves of different ripening characters for MdACO1as fruit treated with different concentrations of ethylene. Flesh firmness (A) starch pattern index (B), skin background colour (C), soluble solids concentration (D), titratable acidity (E), total volatiles (F), and individual volatiles (G–L). Each point depicts the mean of 14 fruit.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2692014&req=5

fig4: Response curves of different ripening characters for MdACO1as fruit treated with different concentrations of ethylene. Flesh firmness (A) starch pattern index (B), skin background colour (C), soluble solids concentration (D), titratable acidity (E), total volatiles (F), and individual volatiles (G–L). Each point depicts the mean of 14 fruit.
Mentions: To establish the level of ethylene needed to induce a ripening response, MdACO1as lines were exposed continuously to a range of ethylene concentrations from 0.01 to 1000 μl l−1 for 14 d at 20 °C. Ethylene response curves were then produced for the six main ripening traits and for the six dominant volatiles (Fig. 4). While there was no clear response to ethylene for titratable acidity and soluble solids concentration, distinct response curves were established for volatile production, firmness, skin background colour, and starch clearance. The general pattern for these curves was sigmoidal, with little or no change in ripening at low concentrations, followed by a rapid increase in response from 0.1 to 10 μl l−1, and little or no change thereafter at which point the process was saturated. However, there were subtle differences in the responses of individual ripening traits, where the majority of the response occurred between 0.1 and 10 μl l−1 for softening, background colour and total volatiles, while in contrast a lower range of 0.01 to 1 μl l−1 was required for starch clearance. Results from the 0.01 and 0.1 μl l−1 ethylene concentrations were indistinguishable from the no-ethylene treatment controls for volatiles, firmness, and background colour suggesting that these concentrations are below the response threshold for these processes. A small increase in starch degradation was observed for the 0.01 μl l−1 ethylene-treated fruit, suggesting a lower response threshold for this trait.

Bottom Line: In this study, it is shown that anti-sense suppression of Malus domestica 1-AMINO-CYCLOPROPANE-CARBOXYLASE OXIDASE (MdACO1) resulted in fruit with an ethylene production sufficiently low to be able to assess ripening in the absence of ethylene.A sustained exposure to ethylene was required to maintain ripening, indicating that the role of ethylene may go beyond that of ripening initiation.These results suggest a conceptual model for the control of individual ripening characters in apple, based on both ethylene dependency and sensitivity.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute For Plant & Food Research Limited, Private Bag 92169, Auckland, New Zealand.

ABSTRACT
In this study, it is shown that anti-sense suppression of Malus domestica 1-AMINO-CYCLOPROPANE-CARBOXYLASE OXIDASE (MdACO1) resulted in fruit with an ethylene production sufficiently low to be able to assess ripening in the absence of ethylene. Exposure of these fruit to different concentrations of exogenous ethylene showed that flesh softening, volatile biosynthesis, and starch degradation, had differing ethylene sensitivity and dependency. Early ripening events such as the conversion of starch to sugars showed a low dependency for ethylene, but a high sensitivity to low concentrations of ethylene (0.01 microl l(-1)). By contrast, later ripening events such as flesh softening and ester volatile production showed a high dependency for ethylene but were less sensitive to low concentrations (needing 0.1 microl l(-1) for a response). A sustained exposure to ethylene was required to maintain ripening, indicating that the role of ethylene may go beyond that of ripening initiation. These results suggest a conceptual model for the control of individual ripening characters in apple, based on both ethylene dependency and sensitivity.

Show MeSH
Related in: MedlinePlus