Methods for the preparation of cell walls from potatoes

SummaryAlthough processed potato tuber texture is an important trait that influences consumer preference, a detailed understanding of tuber textural properties at the molecular level is lacking. Previous work has identified tuber pectin methyl esterase (PME) activity as a potential factor impacting on textural properties, and the expression of a gene encoding an isoform of PME (PEST1) was associated with cooked tuber textural properties. In this study, a transgenic approach was undertaken to investigate further the impact of the PEST1 gene. Antisense and over-expressing potato lines were generated. In over-expressing lines, tuber PME activity was enhanced by up to 2.3-fold; whereas in antisense lines, PME activity was decreased by up to 62%. PME isoform analysis indicated that the PEST1 gene encoded one isoform of PME. Analysis of cell walls from tubers from the over-expressing lines indicated that the changes in PME activity resulted in a decrease in pectin methylation. Analysis of processed tuber texture demonstrated that the reduced level of pectin methylation in the over-expressing transgenic lines was associated with a firmer processed texture. Thus, there is a clear link between PME activity, pectin methylation and processed tuber textural properties.

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Section: Methodsmentioning

confidence: 99%

Pectin engineering to modify product quality in potato

Ross¹,

Morris²,

Ducreux³

et al. 2011

Plant Biotechnology Journal

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“…Cell walls were prepared from tuber samples collected within 1 week of harvest at full maturity. Cell walls were prepared from frozen tuber material largely following the method of Jardine et al (2002) . Briefly, 100 g of tubers were chopped with knives, whilst still frozen, and placed into 500 ml ice-cold mixed cation buffer (MCB) consisting of 10 mM sodium acetate, 3 mM KCl, 2 mM MgCl 2 , and 1 mM CaCl 2 , pH 6.5 containing 0.5 ml Triton X-100 then homogenized using an Ultra-Turrax (IKA, Staufen, Germany; 10×1 min bursts; 3/4 power).…”

Section: Methodsmentioning

confidence: 99%

Potato tuber pectin structure is influenced by pectin methyl esterase activity and impacts on cooked potato texture

Ross¹,

Wright²,

McDougall³

et al. 2010

Journal of Experimental Botany

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Although cooked potato tuber texture is an important trait that influences consumer preference, a detailed understanding of tuber textural properties at the molecular level is lacking. Previous work has identified tuber pectin methyl esterase activity (PME) as a potential factor impacting on textural properties. In this study, tuber PME isoform and gene expression profiles have been determined in potato germplasm with differing textural properties as assessed using an amended wedge fracture method and a sloughing assay, revealing major differences between the potato types. Differences in pectin structure between potato types with different textural properties were revealed using monoclonal antibodies specific for different pectic epitopes. Chemical analysis of tuber pectin clearly demonstrated that, in tubers containing a higher level of total PME activity, there was a reduced degree of methylation of cell wall pectin and consistently higher peak force and work done values during the fracture of cooked tuber samples, demonstrating the link between PME activity, the degree of methylation of cell wall pectin, and cooked tuber textural properties.

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“…When starch removal was complete the cell walls were filtered on a grade 3 sintered glass funnel and sequentially dried in 50, 75, 90 and 100% acetone. (The method is described in more detail as method 1 A in Jardine et al ., 2002 for publication).…”

Section: Methodsmentioning

confidence: 99%

In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side‐chains and abnormal periderm development

et al. 2002

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In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side-chains and abnormal periderm development SummaryRhamnogalacturonan (RG) I is a branched pectic polysaccharide in plant cell walls. Rhamnogalacturonan lyase (eRGL) from Aspergillus aculeatus is able to cleave the RG I backbone at speci®c sites. Transgenic potato (Solanum tuberosum L.) plants were made by the introduction of the gene encoding eRGL, under the control of the granule-bound starch synthase promoter. The eRGL protein was successfully expressed and translated into an active form, demonstrated by eRGL activity in the tuber extracts. The transgenic plants produced tubers with clear morphological alterations, including radial swelling of the periderm cells and development of intercellular spaces in the cortex. Sugar compositional analysis of the isolated cell walls showed a large reduction in galactosyl and arabinosyl residues in transgenic tubers. Immunocytochemical studies using the LM5 (galactan) and LM6 (arabinan) antibodies also showed a large reduction in galactan and arabinan side-chains of RG I. Most of the remaining LM5 epitopes were located in the expanded middle lamella at cell corners of eRGL tubers, which is in contrast to their normal location in the primary wall of wild type tubers. These data suggest that RG I has an important role in anchoring galactans and arabinans at particular regions in the wall and in normal development of the periderm.

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Methods for the preparation of cell walls from potatoes

Cited by 11 publications

References 25 publications

Pectin engineering to modify product quality in potato

Pectin engineering to modify product quality in potato

Potato tuber pectin structure is influenced by pectin methyl esterase activity and impacts on cooked potato texture

In muro fragmentation of the rhamnogalacturonan I backbone in potato (Solanum tuberosum L.) results in a reduction and altered location of the galactan and arabinan side‐chains and abnormal periderm development

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