Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit

The ultrastructural impact of low ethylene biosynthesis (less than 0.5% of normal levels) was evaluated in transgenic (A11.1) tomatoes (Lycopersicon esculentumMill.) expressing an antisense 1-aminocyclopropane-1-carboxylic acid synthase (ACC-S) transgene by means of transmission and environmental sc...

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Autores principales: Sozzi, Gabriel Oscar, Castro, María Agueda
Publicado: 2001
Materias:
cell wall enzymes
ethylene
firmness
Lycopersicon esculentum
organelles
pigments
ripening
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10820132_v7_n1_p59_Sozzi
http://hdl.handle.net/20.500.12110/paper_10820132_v7_n1_p59_Sozzi
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_10820132_v7_n1_p59_Sozzi
record_format dspace
spelling paper:paper_10820132_v7_n1_p59_Sozzi2023-06-08T16:05:50Z Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit Sozzi, Gabriel Oscar Castro, María Agueda cell wall enzymes ethylene firmness Lycopersicon esculentum organelles pigments ripening The ultrastructural impact of low ethylene biosynthesis (less than 0.5% of normal levels) was evaluated in transgenic (A11.1) tomatoes (Lycopersicon esculentumMill.) expressing an antisense 1-aminocyclopropane-1-carboxylic acid synthase (ACC-S) transgene by means of transmission and environmental scanning electron microscopy. In 48-day mature green fruit, no significant ultrastructural differences were found between transgenic and control tomatoes. In 78-day control fruit, which were overripe and showed deteriorated texture, many areas of the cytoplasm were devoid of structures, and micrographs showed cell collapse with folding and dissolution of the cell wall. On the other hand, in 90-day transgenic fruit, which were firm and not ripe, the cytoplasm showed a relatively high electron density. Plastids retained remnants of chloroplast thylakoids along with significant amounts of osmiophylic plastoglobuli, but lycopene was not detected. Conspicuous starch granules were observed in mature green transgenic tomatoes, but were not detected in 90-day chlorochromoplasts. Electron-dense regions reflecting the integrity of the middle lamella alternated with other partially degraded regions. This incipient dissolution of the middle lamella pectic polymers may be attributable to nonenzymatic deaggregation or to cell-wall hydrolases which could be ethylene independent or responsive to very low levels of ethylene. Besides, cells were attached along extended contact areas and appeared turgid. This feature may provide an explanation of firmness retention that does not solely involve cell walls. Disruption of the middle lamella and development of lycopene crystalloids were observed when exogenous ethylene (12 ppm) was applied. © 2001, Sage Publications. All rights reserved. Fil:Sozzi, G.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Castro, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2001 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10820132_v7_n1_p59_Sozzi http://hdl.handle.net/20.500.12110/paper_10820132_v7_n1_p59_Sozzi
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic cell wall enzymes
ethylene
firmness
Lycopersicon esculentum
organelles
pigments
ripening
spellingShingle cell wall enzymes
ethylene
firmness
Lycopersicon esculentum
organelles
pigments
ripening
Sozzi, Gabriel Oscar
Castro, María Agueda
Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
topic_facet cell wall enzymes
ethylene
firmness
Lycopersicon esculentum
organelles
pigments
ripening
description The ultrastructural impact of low ethylene biosynthesis (less than 0.5% of normal levels) was evaluated in transgenic (A11.1) tomatoes (Lycopersicon esculentumMill.) expressing an antisense 1-aminocyclopropane-1-carboxylic acid synthase (ACC-S) transgene by means of transmission and environmental scanning electron microscopy. In 48-day mature green fruit, no significant ultrastructural differences were found between transgenic and control tomatoes. In 78-day control fruit, which were overripe and showed deteriorated texture, many areas of the cytoplasm were devoid of structures, and micrographs showed cell collapse with folding and dissolution of the cell wall. On the other hand, in 90-day transgenic fruit, which were firm and not ripe, the cytoplasm showed a relatively high electron density. Plastids retained remnants of chloroplast thylakoids along with significant amounts of osmiophylic plastoglobuli, but lycopene was not detected. Conspicuous starch granules were observed in mature green transgenic tomatoes, but were not detected in 90-day chlorochromoplasts. Electron-dense regions reflecting the integrity of the middle lamella alternated with other partially degraded regions. This incipient dissolution of the middle lamella pectic polymers may be attributable to nonenzymatic deaggregation or to cell-wall hydrolases which could be ethylene independent or responsive to very low levels of ethylene. Besides, cells were attached along extended contact areas and appeared turgid. This feature may provide an explanation of firmness retention that does not solely involve cell walls. Disruption of the middle lamella and development of lycopene crystalloids were observed when exogenous ethylene (12 ppm) was applied. © 2001, Sage Publications. All rights reserved.
author Sozzi, Gabriel Oscar
Castro, María Agueda
author_facet Sozzi, Gabriel Oscar
Castro, María Agueda
author_sort Sozzi, Gabriel Oscar
title Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
title_short Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
title_full Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
title_fullStr Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
title_full_unstemmed Ripening-Associated Microstructural Changes in Antisense ACC Synthase Tomato Fruit
title_sort ripening-associated microstructural changes in antisense acc synthase tomato fruit
publishDate 2001
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_10820132_v7_n1_p59_Sozzi
http://hdl.handle.net/20.500.12110/paper_10820132_v7_n1_p59_Sozzi
work_keys_str_mv AT sozzigabrieloscar ripeningassociatedmicrostructuralchangesinantisenseaccsynthasetomatofruit
AT castromariaagueda ripeningassociatedmicrostructuralchangesinantisenseaccsynthasetomatofruit
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