An Antisense Pectin Methylesterase Gene Alters Pectin Chemistry and Soluble Solids in Tomato Fruit

Tieman, Denise M.; Harriman, Robert W.; Ramamohan, G.; Handa, Avtar K.

doi:10.2307/3869525

Cited by 111 publications

(41 citation statements)

References 33 publications

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“…In PME antisense pericarp, the 34-kDa PME isoform was undetectable whereas the 37-kDa polypeptide, which cross-reacts with polyclonal fruit PME antibodies (7), remained unchanged, at all stages of fruit development and ripening. These results are consistent with the earlier report showing that the expression of a fruit-specific PME antisense gene impairs accumulation of the major PME isoforms (7,13).…”

Section: Resultssupporting

confidence: 93%

“…The pericarp was frozen in liquid nitrogen and held at Ϫ80°C until being used for the analysis of methanol and ethanol content or purification of ADH. PME Activity and Immunoblot Analysis-Changes in PME activity and protein were determined as described earlier (6,7).…”

Section: Methodsmentioning

confidence: 99%

“…We have created transgenic tomato fruits with severely impaired expression of PME by introducing a fruit-specific PME antisense gene under the control of cauliflower mosaic virus 35S promoter (7). We compared methanol production in the wildtype and the PME antisense tomato fruits to examine whether the arrest of PME gene expression results in diminished production of methanol.…”

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confidence: 99%

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Pectin Methylesterase Regulates Methanol and Ethanol Accumulation in Ripening Tomato (Lycopersicon esculentum) Fruit

Frenkél¹,

Peters²,

Tieman³

et al. 1998

Journal of Biological Chemistry

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110

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We provide genetic evidence that the production of methanol in tomato fruit is regulated by pectin methylesterase (PME, EC 3.1.1.11), an enzyme that catalyzes demethoxylation of pectins. The role of PME in methanol production in tomato fruit was examined by relating the tissue methanol content to the PME enzymatic activity in wild-type Rutgers and isogenic PME antisense fruits with lowered PME activity. In the wild-type, fruit development and ripening were accompanied by an increase in the abundance of PME protein and activity and a corresponding ripening-related increase in methanol content. In the PME antisense pericarp, the level of methanol was greatly reduced in unripe fruit, and diminished methanol content persisted throughout the ripening process. The close correlation between PME activity and levels of methanol in fruit tissues from wildtype and a PME antisense mutant indicates that PME is the primary biosynthetic pathway for methanol production in tomato fruit. Interestingly, ethanol levels that were low and unchanged during ripening of wild-type tomatoes increased progressively with the ripening of PME antisense fruit. In vitro studies indicate that methanol is a competitive inhibitor of the tomato alcohol dehydrogenase (ADH, EC 1.1.1.1) activity suggesting that ADH-catalyzed production of ethanol may be arrested by methanol accumulation in the wild-type but not in the PME mutant where methanol levels remain low.Methanol is emitted by actively growing plant tissues (1) and ripening fruit (2). A major source of methanol may be pectin methyl esters (3) that are de-esterified to methanol and pectic substances by a PME 1 -catalyzed reaction (4). Although methanol production is correlated with PME activity in germinating seeds or other plant tissues (1), the role of PME in methanol accumulation in plants has not been firmly established (4,5).A developmentally regulated increase in PME gene expression occurs in developing tomato fruit (6) and may be used as a test system to relate PME activity to methanol metabolism. We have created transgenic tomato fruits with severely impaired expression of PME by introducing a fruit-specific PME antisense gene under the control of cauliflower mosaic virus 35S promoter (7). We compared methanol production in the wildtype and the PME antisense tomato fruits to examine whether the arrest of PME gene expression results in diminished production of methanol. Our results show that methanol accumulation in ripening tomato pericarp of either the wild-type or the PME antisense is related to PME activity, suggesting that the PME activity is the primary source of methanol production in tomato fruits. A surprising finding is that the tissue methanol and ethanol content in ripening tomato fruit were inversely related.

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Section: Resultssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Pectin Methylesterase Regulates Methanol and Ethanol Accumulation in Ripening Tomato (Lycopersicon esculentum) Fruit

Frenkél¹,

Peters²,

Tieman³

et al. 1998

Journal of Biological Chemistry

Self Cite

110

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“…Most studies reported so far regarding plant development mainly focused on the relationships of the PME with fruit maturation [2]. However, little is known about the role of this enzyme in other aspects of plant development particularly in cell expansion and maturation of the cell wall [3].…”

Section: Introductionmentioning

confidence: 99%

Molecular cloning and characterisation of a putative pectin methylesterase cDNA in Arabidopsis thaliana (L.)

et al. 1994

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Pectin methylesterase (PME) is a cell wall enzyme that catalyses the de-esterification of pectins leading to fundamental changes which confer new properties to the micro-environment of each cell. In order to elucidate the meaning of PME-mediated changes of pectin in the time course of cell differentiation, we attempted to study the regulation of PME genes in Arabidopsis thaliana. In this report, the first full eDNA sequence showing sequence similarities with other PME genes characterised so far in other plant species has been isolated from an Arabidopsis shoot cDNA library. This ATPMEI eDNA is 1,970 bp long and contains an open reading frame encoding a protein of 64,1 kDa and a basic pI of 8.7 as predicted from the nucleotide sequence. Northern blot analyses denoted changes in the expression level of the ATPME1 mRNA according to plant organs. High mRNA levels were found in young developing organs such as cauline leaves while they were significantly lower in rosette leaves, stems and inflorescences, and almost undetectable in roots. Beside this molecular approach, isoelectrofocusing analyses revealed the occurrence of three PME isoforms in Arabidopsis. Two PME isoforms with pI values of 4.9 and 9.1 were found throughout the plant, but at a higher level in the root, while an other PME isoform with a pI of 5.7 was essentially detected in the inflorescence. The relationship between our observations and the data reported for other plant species is discussed.

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“…However, in these genotypes, the absence of the normal ripening-associated CW metabolism is just one of many processes affected, so it is not possible to conclude that CW metabolism of the mutants per se contributes to reduced pathogen susceptibility (18). Fruit in which the expression of genes encoding CWDEs such as PG and pectin methyl esterase has been suppressed apparently have increased tissue integrity at fully ripe or overripe stages (18)(19)(20)(21). The suppression of the tomato fruit ripeningassociated Exp gene, LeExp1, resulted in firmer fruit with prolonged shelf-life (22), but did not reduce the susceptibility to Botrytis cinerea and Alternaria alternata (4).…”

mentioning

confidence: 99%

The intersection between cell wall disassembly, ripening, and fruit susceptibility to Botrytis cinerea

Cantu

Vicente²,

Greve³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

268

209

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Fruit ripening is characterized by processes that modify texture and flavor but also by a dramatic increase in susceptibility to necrotrophic pathogens, such as Botrytis cinerea. Disassembly of the major structural polysaccharides of the cell wall (CW) is a significant process associated with ripening and contributes to fruit softening. In tomato, polygalacturonase (PG) and expansin (Exp) are among the CW proteins that cooperatively participate in ripening-associated CW disassembly. To determine whether endogenous CW disassembly influences the ripening-regulated increase in necrotropic pathogen susceptibility, B. cinerea susceptibility was assessed in transgenic fruit with suppressed polygalacturonase (LePG) and expansin (LeExp1) expression. Suppression of either LePG or LeExp1 alone did not reduce susceptibility but simultaneous suppression of both dramatically reduced the susceptibility of ripening fruit to B. cinerea, as measured by fungal biomass accumulation and by macerating lesion development. These results demonstrate that altering endogenous plant CW disassembly during ripening influences the course of infection by B. cinerea, perhaps by changing the structure or the accessibility of CW substrates to pathogen CW-degrading enzymes. Recognition of the role of ripening-associated CW metabolism in postharvest pathogen susceptibility may be useful in the design and development of strategies to limit pathogen losses during fruit storage, handling, and distribution.expansin ͉ polygalacturonase ͉ tomato ͉ plant pathogen

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An Antisense Pectin Methylesterase Gene Alters Pectin Chemistry and Soluble Solids in Tomato Fruit

Cited by 111 publications

References 33 publications

Pectin Methylesterase Regulates Methanol and Ethanol Accumulation in Ripening Tomato (Lycopersicon esculentum) Fruit

Pectin Methylesterase Regulates Methanol and Ethanol Accumulation in Ripening Tomato (Lycopersicon esculentum) Fruit

Molecular cloning and characterisation of a putative pectin methylesterase cDNA in Arabidopsis thaliana (L.)

The intersection between cell wall disassembly, ripening, and fruit susceptibility to Botrytis cinerea

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