Epigenetic control of gene expression and secondary metabolism in halved strawberry fruit during chilled storage

Baldwin, Ashley 2023. Epigenetic control of gene expression and secondary metabolism in halved strawberry fruit during chilled storage. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Summary Strawberries (Fragaria x ananassa) have a short shelf-life and are therefore transported and stored at low temperatures. Cold storage can be considered as both positive and negative for the consumer as it is required to prolong post-harvest life by slowing down respiration and growth of spoilage microorganisms. However, cold storage is also a stress that can result in loss of flavour and nutritional value from harvest, through the supply chain to the consumer. Here, using RNA-seq, gene expression changes taking place during cold storage in halved strawberry fruit have been unravelled revealing many processes and pathways potentially affected by the storage. Using volatile organic compound (VOC) analysis, it has also been shown that VOC profiles differ over cold storage. Esters are the most abundant VOC within strawberry aroma and are synthesised by the enzyme alcohol acyltransferase (AAT) which, was shown here to decrease in expression over cold storage. Other VOCs are produced by different biosynthetic pathways and enzymes. For example, 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMMF) is produced by an o-methyltransferase (OMT). Potential overexpression of these genes transiently over storage resulted in changed VOC profiles, and AAT over-expression changed sensorial perception of the aroma, highlighting the importance of AAT and OMT for strawberry aroma. It was hypothesised that some changes in secondary metabolism such as VOC production during storage might be attributed to epigenetic down-regulation of key genes. To test this hypothesis, RNA-seq was combined with ChIP-seq, pulling down DNA sequences associated with the trimethylation of histone H3 at lysine 27 (H3K27me3), known to be a silencing mark. Four hundred genes were down regulated during storage in the RNA-seq experiment and gained association with the H3K27me3 mark during storage suggesting that they may be under epigenetic regulation. Overall, the genes studied may be useful to provide markers for targeted breeding to improve flavour retention during storage and thus contribute to a healthier human diet.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	2 April 2024
Last Modified:	12 Apr 2024 08:27
URI:	https://orca.cardiff.ac.uk/id/eprint/167656

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