Browsing by Author "Nayakoti, Swapna"

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    Understanding asparagus tip breakdown postharvest at a molecular and cellular level
    (International Society for Horticultural Science, 2023-10-09) Nayakoti, Swapna; Collings, Emma; Landahl, Sandra; Chinn, John; Terry, Leon A; Christofides, S.; Alamer, M. Carmen; Rogers, Hilary
    Asparagus has a very limited season in the UK and a short shelf-life. Tip breakdown occurs sporadically during chilled storage and limits shelf-life. It is characterized by internal browning and is accompanied by an unpleasant aroma. The change in aroma can be the first sign of the breakdown, and results in waste as whole batches of asparagus need to be discarded. Data suggest that the breakdown may not be initiated by microbial action, but the underlying mechanisms are yet to be fully elucidated. Tip breakdown occurs more frequently in faster growing spears when growing temperatures are higher. To explore whether the faster growth is associated with larger cells, cell size was compared in spear tips of a cultivar which is more susceptible to tip rot, ‘Aspalim’, and a cultivar in which tip rot very rarely occurs, ‘Early California’. However, no significant differences were found. Transcriptomes were sequenced from healthy spears, and spears in which symptoms of tip breakdown could be seen visually, to assess changes in gene expression during the development of the tip breakdown. More genes were upregulated in spears showing tip breakdown compared to healthy spears after 14 days of chilled storage. The largest functional group of differentially expressed genes is related to DNA binding and transcription regulation which may provide useful information on the overall regulation of the breakdown process.
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    Understanding the mechanisms responsible for postharvest tip breakdown in asparagus: a biochemical approach
    (International Society for Horticultural Science, 2023-10-09) Collings, Emma; Landahl, Sandra; Jodkowska, Monika; Nayakoti, Swapna; Chinn, John; Rogers, Hilary; Terry, Leon A; Alamar, M. Carmen
    The UK asparagus season is relatively short (from April to June), resulting in large quantities of spears being imported to provide year-round supply. Currently, asparagus quality can only be maintained for one week, plus seven days shelf-life, using cold storage alone. A limiting factor, which contributes significantly towards commercial losses, is the development of the postharvest physiological disorder tip breakdown (also known as tip rot). The disorder is characterised by darkening tips followed by the presence of water-soaked bracts at the tip of the spear and a foul odour. However, the underlying causes of tip breakdown have not yet been fully elucidated. We hypothesise that fast growth, slow rate of sugar transport and localised cell death may be key components of the mechanism. To gain more insight into tip breakdown development, two asparagus cultivars with low and high susceptibility to tip breakdown (‘Early California’ and ‘Aspalim’, respectively) were grown under controlled conditions and subjected to warm (28/14 °C) and cold (18/8 °C) day/ night temperatures. Harvested spears were subjected to shelf-life storage, 14 days at 7 °C, to subjectively assess early symptoms and further development of tip breakdown. Spears were snap frozen for subsequent biochemical analysis (viz. non-structural carbohydrates and plant growth regulators [PGRs]). Results showed that ‘Aspalim’ spears grown at warmer temperatures had higher incidence of tip breakdown than ‘Early California’. The relationship between incidence and severity of asparagus tip breakdown and the role of PGRs and sugar content during the season, as affected by genotype and growing conditions, are also discussed. The fundamental mechanistic understanding of asparagus tip breakdown will aid to implement optimum postharvest storage strategies to reduce food loss and the associated carbon footprint.