Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Variation For Flour Colour In Western Australia Adapted Wheat: Molecular Markers QTL Analysis And Candidate Genes

Karon Ryan^1,2 , Natalie Parry^1,3 , Natasha Teakle^1,3 , Katia Stefanova³ , William Lambe³ , Robyn McLean³ , Iain Barclay³ , Robin Wilson³ , Rudi Appels^1,3 , Michael Francki^1,2,3

¹  State Agricultural and Biotechnology Centre, Murdoch University, South Street, Murdoch, WA 6150, Australia.

²  Value Added Wheat Co-operative Research Centre Limited, 1 Rivett Road, North Ryde, NSW, 2113, Australia.

³  Department of Agriculture, 3 Baron-Hay Court, South Perth, WA, 6151, Australia.

Flour colour, which ranges from bright white to creamy yellow, is an important quality trait in wheat for end-use products and is determined by the accumulation of carotenoids in the endosperm. Flour colour (brightness: Minolta b*) and xanthophyll content analysed in three doubled haploid (DH) populations derived from Western Australia adapted germplasm had a strong positive correlation, indicating that xanthophylls are the pigment source for b*. Quantitative trait loci (QTL) analysis across the DH populations of Ajana/WAWHT2074, Carnamah/WAWHT2046 and Westonia*2/Janz showed variation in homoeoalleles controlling flour colour and xanthophyll content within these populations. Highly significant (P<0.001) QTLs for b* and xanthophyll content were found to be co-located in the same chromosomal regions on 3AS, 7AL and 7BS. Previously, a common region of QTLs for both b* and xanthophyll content was identified on 3BS and 7AL in a Sunco/Tasman population, indicating that b* is controlled by homoeoalleles in wheat germplasm. Molecular markers were developed from genes encoding three carotenoid enzymes: Geranylgeranyltransferase I ß–subunit (GGT-IB), Rab geranylgeranyltransferase component A (RGGT-A) and Lycopene ß-cyclase (LBC). The xanthophyll-related genes were identified in rice and aligned to QTLs controlling b* and xanthophyll content on wheat chromosomes. Mapping using nullisomic-tetrasomic cytogenetic stocks confirmed GGT-IB and RGGT-A on 3B in the co-location of QTLs for b* and xanthophyll content in the Sunco/Tasman population. GGT-IB was further mapped to the proximal chromosomal bin location of 3BS-1 using deletion lines. RGGT-A is located in the proximal bin of either 3BS or 3BL and LBC is on homoeologous group 7.