Ultrastructural and physiological aspects of bruising in potatoes

Edgell, T., 2000. Ultrastructural and physiological aspects of bruising in potatoes. PhD, Nottingham Trent University.

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Abstract

To establish what influences blackspot susceptibility in potato tubers, physiological and biochemical parameters have been investigated in cultivars, Pentland Dell, Maris Piper and Record, during long term storage.

Measurements of respiration, dopachrome formation, cation leakage and bruise susceptibility, were made at regular intervals through storage. Results indicated that the biochemical potential for producing melanin (dopachrome formation at 475 nm) did not correlate with measurements of bruise susceptibility, (bruise severity following impact). This indicated that changes in tuber biochemistry did not influence blackspot susceptibility through storage and that tuber physiology and structural integrity played an important role. Cultivar had a significant influence on tuber physiology and on blackspot susceptibility. Maris Piper was less susceptible to blackspot bruise formation than Pentland Dell and Record, this correlated with a low respiration rate, cation leakage and potential dopachrome formation.

Temperature at impact had a significant effect on bruise susceptibility. Tubers impacted at 5 °C displayed a greater percentage bruise formation than tubers impacted at 10 °C.

Time-course investigations following impact found that respiration and potassium, magnesium and calcium ion leakage increased immediately following impact whilst turgor declined. These responses occurred in particular following impact during early storage.

Tubers of Pentland Dell were examined following impact using transmission electron microscopy. An ultrastructural sequence of events was highlighted which occurred during blackspot formation, firstly a collapse of intracellular compartmentation, followed by an apparent increased ribosomal and mitochondrial abundance and a darkening of the cytoplasm with the development of melanin.

Ultrastructural investigations found that at harvest impacted tubers developed microscopic shatter, the tonoplast was disrupted showing vesicularisation, with increased numbers of mitochondrial sections and nuclear invaginations. Conversely following storage, impacted tubers developed blackspot bruising with melanin forming within the cytoplasm, along the cell wall and surrounding the starch grains.

Item Type:	Thesis
Creators:	Edgell, T.
Date:	2000
ISBN:	9781369313000
Identifiers:	Number Type PQ10183002 Other
Rights:	This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that no quotation from the thesis and no information from it may be published without the authors prior written consent.
Divisions:	Schools > School of Animal, Rural and Environmental Sciences
Record created by:	Jeremy Silvester
Date Added:	28 Aug 2020 12:16
Last Modified:	14 Jun 2023 09:36
URI:	https://irep.ntu.ac.uk/id/eprint/40572

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