Preprint Article Version 1 This version is not peer-reviewed

Molecular Characterization of a Supergene Conditioning Super-High Vitamin C in Kiwifruit Hybrids

Version 1 : Received: 27 June 2019 / Approved: 28 June 2019 / Online: 28 June 2019 (08:09:04 CEST)

A peer-reviewed article of this Preprint also exists.

McCallum, J.; Laing, W.; Bulley, S.; Thomson, S.; Catanach, A.; Shaw, M.; Knaebel, M.; Tahir, J.; Deroles, S.; Timmerman-Vaughan, G.; Crowhurst, R.; Hilario, E.; Chisnall, M.; Lee, R.; Macknight, R.; Seal, A. Molecular Characterisation of a Supergene Conditioning Super-High Vitamin C in Kiwifruit Hybrids. Plants 2019, 8, 237. McCallum, J.; Laing, W.; Bulley, S.; Thomson, S.; Catanach, A.; Shaw, M.; Knaebel, M.; Tahir, J.; Deroles, S.; Timmerman-Vaughan, G.; Crowhurst, R.; Hilario, E.; Chisnall, M.; Lee, R.; Macknight, R.; Seal, A. Molecular Characterisation of a Supergene Conditioning Super-High Vitamin C in Kiwifruit Hybrids. Plants 2019, 8, 237.

Journal reference: Plants 2019, 8, 237
DOI: 10.3390/plants8070237

Abstract

During analysis of kiwifruit derived from hybrids between the high AsA species Actinidia eriantha and A. chinensis var chinensis, we observed bimodal segregation of fruit AsA concentration suggesting major gene segregation. To test this hypothesis we performed whole-genome sequencing on pools of high and low AsA fruit from tetraploid A. chinensis var. deliciosa x A. eriantha backcross families. Pool-GWAS revealed a single QTL spanning more than 5 Mbp on chromosome 26, which we denote as qAsA26.1. A co-dominant PCR marker was used to validate this association in four diploid (A. chinensis x A. eriantha) x A. chinensis backcross families, showing that the eriantha allele at this locus increases fruit AsA levels by 250 mg/100 g fresh weight. Inspection of genome composition and recombination in other A. chinensis genetic maps confirmed that the qAsA26.1 region bears hallmarks of suppressed recombination. The molecular fingerprint of this locus was examined in leaves of backcross validation families by RNASEQ. This confirmed strong allelic expression bias across this region as well as differential expression of transcripts on other chromosomes. This evidence suggests that the region harboring qAsA26.1 constitutes a supergene, which may condition multiple pleiotropic effects on metabolism.

Subject Areas

kiwifruit; genomics; polyploidy; breeding; ascorbic acid; vitamin C

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