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J Exp Bot. 2011 Mar;62(6):2217-28. doi: 10.1093/jxb/erq423. Epub 2011 Jan 12.

Identification of a major QTL controlling the content of B-type starch granules in Aegilops.

Author information

1
John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.

Abstract

Starch within the endosperm of most species of the Triticeae has a unique bimodal granule morphology comprising large lenticular A-type granules and smaller near-spherical B-type granules. However, a few wild wheat species (Aegilops) are known to lack B-granules. Ae. peregrina and a synthetic tetraploid Aegilops with the same genome composition (SU) were found to differ in B-granule number. The synthetic tetraploid had normal A- and B-type starch granules whilst Ae. peregrina had only A-granules because the B-granules failed to initiate. A population segregating for B-granule number was generated by crossing these two accessions and was used to study the genetic basis of B-granule initiation. A combination of Bulked Segregant Analysis and QTL mapping identified a major QTL located on the short arm of chromosome 4S that accounted for 44.4% of the phenotypic variation. The lack of B-granules in polyploid Aegilops with diverse genomes suggests that the B-granule locus has been lost several times independently during the evolution of the Triticeae. It is proposed that the B-granule locus is susceptible to silencing during polyploidization and a model is presented to explain the observed data based on the assumption that the initiation of B-granules is controlled by a single major locus per haploid genome.

PMID:
21227932
PMCID:
PMC3060699
DOI:
10.1093/jxb/erq423
[Indexed for MEDLINE]
Free PMC Article

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