Scientific Publications
The impact of Cas9-mediated mutagenesis of genes encoding potato starch-branching enzymes on starch structural properties and in vitro digestibility.
Carbohydrate Polymers
The staple human diet is based on starch-based foods. The digestibility of these foods is affected by the amylose content of their starch. Amylose content can be manipulated by alterations to genes encoding starch-branching enzymes (SBEs), for example by gene editing with Cas9 technology. In this paper we investigated the impact of Cas9-mediated mutagenesis of SBEs in potato on starch amylose content, structural properties and digestibility.
Starches from four potatoes with edited SBE genes were tested. One essentially lacked both SBE1 and SBE2, two essentially lacked SBE2 and had reduced SBE1, and one had reduced SBE2 only. An in vitro digestion protocol was used to monitor digestibility. Starch structure and thermal properties were characterised by DSC and XRD. The impact of thermal treatment on digestibility was studied in native and gelatinised starch, and after either 18 hours or 7 days of retrogradation.
Native potato starches were all highly resistant to digestion, with differences in digestibility between mutants likely reflecting differences in granule size and morphology. Freshly gelatinised starches all digested at a similar rate, regardless of SBE status. All starches from potatoes with modified SBE levels had higher gelatinisation temperatures than that from wild type potatoes and were found by DSC to retrograde more rapidly. Following 7 days retrogradation starch from three of the lines with modified SBE levels was less digestible than starch from wild-type potatoes, indicating that reductions in SBE in potato may be beneficial to health by increasing the amount of fibre reaching the colon. 248 words
Carbohydrate Polymers
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