Postharvest evaluation of transgenic tomatoes with reduced levels of polygalacturonase: processing, firmness and disease resistance

Kramer, Matthew; Sanders, Rick; Bolkan, Hassan; Waters, C D; Sheeny, Raymond E.; Hiatt, William R.

doi:10.1016/0925-5214(92)90007-c

Cited by 151 publications

(89 citation statements)

References 21 publications

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“…It is generally assumed that self-disassembly of the fruit wall contributes to susceptibility because many of the fruit CWDEs that participate in fruit wall metabolism also are produced by the invading pathogens and secreted into fruit tissues (16). Ripeningimpaired tomato fruit with the Nr or nor mutations show reduced ripening-associated softening and decreased susceptibility to patho- gens (17,18). 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).…”

mentioning

confidence: 90%

“…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%

“…Ripeningimpaired tomato fruit with the Nr or nor mutations show reduced ripening-associated softening and decreased susceptibility to patho- gens (17,18). 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).…”

mentioning

confidence: 99%

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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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confidence: 90%

mentioning

confidence: 99%

mentioning

confidence: 99%

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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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“…Additionally, the extensive depolymerization and release of uronic acids, in predominately oligomeric form, from tomato pericarp discs is largely a cut-surface (wound) phenomenon and is dependent on the presence of buffers of suitable pH and ionic strength (Huber and Lee, 1989). Severa1 investigators have reported that juice from PG antisense fruit was of significantly higher viscosity than juice from the untransformed fruit (Kramer et al, 1990;Schuch et al, 1991;Kramer et al, 1992). These observations indicate that the environment provided by the release of endogenous cellular fluids is favorable for enhancing polyuronide depolymerization and, therefore, accentuating differences in the PG antisense versus normal tomato lines.…”

Section: Possible Role Of Polyuronide Depolymerization and Pc In Ripementioning

confidence: 99%

“…With one exception (Kramer et al, 1992), introduction of PG antisense constructs into various tomato lines has had little effect on fruit characteristics until the late stages of ripening (Kramer et al, 1990;Schuch et al, 1991). Schuch et al (1991) observed that the reduced PG levels (>99% reduction) in tomato fruit containing the PG antisense gene, although not influencing firmness as assessed by whole fruit compression, resulted in a much reduced susceptibility to cracking, decay, and other damage, particularly during simulated transport studies.…”

Section: Possible Role Of Polyuronide Depolymerization and Pc In Ripementioning

confidence: 99%

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

1993

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Avocado (Persea americana) fruit experience a rapid and extensive loss of firmness during ripening. In this study, we examined whether the chelator solubility and molecular weight of avocado polyuronides paralleled the accumulation of polygalacturonase (PC) activity and loss in fruit firmness. Polyuronides were derived from ethanolic precipitates of avocado mesocarp prepared using a procedure to rapidly inactivate endogenous enzymes. During ripening, chelator (cyclohexane-trans-l,2-diamine tetraacetic acid [CDlA])-soluble polyuronides increased from approximately 30 to 40 pg of galacturonic acid equivalents (mg alcohol-insoluble solids)-' in preripe fruit to 150 to 170 pg mg-' in postclimacteric fruit. In preripe fruit, chelator-extractable polyuronides were of high molecular weight and were partially excluded from Sepharose CL-26-300 gel filtration media. Avocado polyuronides exhibited marked downshifts in molecular weight during ripening. At the postclimacteric stage, nearly all chelator-extractable polyuronides, which constituted from 75 to 90% of total cell wall uronic acid content, eluted near the total volume of the filtration media. Rechromatography of low molecular weight polyuronides on BioCel P-4 disclosed that oligomeric uronic acids are produced in vivo during avocado ripening. l h e gel filtration behavior and pattern of depolymerization of avocado polyuronides were not influenced by the polyuronide extraction protocol (imidazole versus CDTA) or by chromatographic conditions designed to minimize interpolymeric aggregation. Polyuronides from ripening tomato (fycopersicon esculentum) fruit extracted and chromatographed under conditions identical with those used for avocado polyuronides exhibited markedly less rapid and less extensive downshifts in molecular weight during the transition from mature-green to fully ripe. Even during a 9-d period beyond the fully ripe stage, tomato fruit polyuronides exhibited limited additional depolymerization and did not include oligomeric species. A comparison of the data for the avocado and tomato fruit indicates that downshifts in polyuronide molecular weight are a prominent feature of avocado ripening and may also explain why molecular down-regulation of PC (EC 3.2.1.15) in tomato fruit has resulted in minimal effects on fruit performance until the terminal stages of ripening.Avocado fruit soften extensively during ripening, with mesocarp firmness, measured in terms of resistance to penetration, exceeding 450 N at the preripe stage and decreasing severa1 orders of magnitude during ripening (Pesis et al., 1978; Awad and Young, 1979; O'Donoghue and Huber,

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Pectic Enzymes in Tomatoes

Kalamaki¹,

Stoforos²,

Taoukis³

2006

Food Biochemistry and Food Processing

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Postharvest evaluation of transgenic tomatoes with reduced levels of polygalacturonase: processing, firmness and disease resistance

Cited by 151 publications

References 21 publications

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

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

Polyuronides in Avocado (Persea americana) and Tomato (Lycopersicon esculentum) Fruits Exhibit Markedly Different Patterns of Molecular Weight Downshifts during Ripening

Pectic Enzymes in Tomatoes

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