A high soluble-fibre allele in wheat encodes a defective cell wall peroxidase responsible for dimerization of ferulate moieties on arabinoxylan

A - Papers appearing in refereed journals

Mitchell, R. A. C., Oszvald, M., Pellny, T. K., Freeman, J., Halsey, K., Sparks, C. A., Huttly, A. K., Specel, S., Leverington-Waite, M., Griffiths, S., Shewry, P. R. and Lovegrove, A. 2023. A high soluble-fibre allele in wheat encodes a defective cell wall peroxidase responsible for dimerization of ferulate moieties on arabinoxylan. bioRxiv. https://doi.org/10.1101/2023.03.08.531735

AuthorsMitchell, R. A. C., Oszvald, M., Pellny, T. K., Freeman, J., Halsey, K., Sparks, C. A., Huttly, A. K., Specel, S., Leverington-Waite, M., Griffiths, S., Shewry, P. R. and Lovegrove, A.
Abstract

Increasing dietary fibre (DF) intake is an important target to improve health and an attractive strategy for this is to increase the fibre content of staple foods, particularly white bread which is the staple food in many countries. DF in wheat white flour is derived principally from the endosperm cell wall polysaccharide arabinoxylan (AX) and the water-extractable form of this (WE-AX) accounts for the majority of soluble dietary fibre (SDF), which is believed to confer particular health benefits. We previously identified QTLs for soluble dietary fibre (SDF) on 1B and 6B chromosomes in wheat in biparental populations. Here we show that the 6B high SDF allele encodes a peroxidase protein (PER1-v) with a single missense compared to the more common low SDF form (PER1). Wheat lines with the natural PER1-v allele and with an induced knock-out mutation in PER1 showed similar characteristics of reduced dimerization of ferulate associated with water-extractable WE-AX. Decreased ferulate dimerization is associated with decreased cross-linking of the WE-AX chains and increased solubility of AX. Transiently expressed PER1_RFP fusion driven by native promoter in wheat endosperm was shown to localise to cell walls whereas PER1-v_RFP did not; we therefore propose that PER1-v lacks capacity to dimerise AX ferulate in vivo due to mis-localisation. PER1 is the first peroxidase reported to be responsible for oxidative coupling of ferulate on AX, a key process in all grass cell walls. Understanding its role and the effect of variants on AX properties offers a route to control the properties of wheat DF in the human diet.

Year of Publication2023
JournalbioRxiv
Digital Object Identifier (DOI)https://doi.org/10.1101/2023.03.08.531735
Open accessPublished as non-open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDFW - Designing Future Wheat - Work package 2 (WP2) - Added value and resilience
Delivering high dietary fibre via improved wheat cultivars and products
Xylan arabinosyl transferases: identification and characterisation of their role in determining properties of grass cell walls
Output statusPublished
Publication dates
Online10 Mar 2023
PublisherPublic Library of Science (PLOS)

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