title: Quantitative trait loci and candidate genes associated with starch pasting viscosity characteristics in cassava (Manihot esculenta Crantz).
abstract: Starch pasting viscosity is an important quality trait in cassava (Manihot esculenta Crantz) cultivars. The aim here was to identify loci and candidate genes associated with the starch pasting viscosity. Quantitative trait loci (QTL) mapping for seven pasting viscosity parameters was carried out using 100 lines of an F1 mapping population from a cross between two cassava cultivars Huay Bong 60 and Hanatee. Starch samples were obtained from roots of cassava grown in 2008 and 2009 at Rayong, and in 2009 at Lop Buri province, Thailand. The traits showed continuous distribution among the F1 progeny with transgressive variation. Fifteen QTL were identified from mean trait data, with Logarithm of Odds (LOD) values from 2.77-13.01 and phenotype variations explained (PVE) from10.0-48.4%. In addition, 48 QTL were identified in separate environments. The LOD values ranged from 2.55-8.68 and explained 6.6-43.7% of phenotype variation. The loci were located on 19 linkage groups. The most important QTL for pasting temperature (PT) (qPT.1LG1) from mean trait values showed largest effect with highest LOD value (13.01) and PVE (48.4%). The QTL co-localised with PT and pasting time (PTi) loci that were identified in separate environments. Candidate genes were identified within the QTL peak regions. However, the major genes of interest, encoding the family of glycosyl or glucosyl transferases and hydrolases, were located at the periphery of QTL peaks. The loci identified could be effectively applied in breeding programmes to improve cassava starch quality. Alleles of candidate genes should be further studied in order to better understand their effects on starch quality traits.
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand.
authors.forename: T
authors.initials: T
authors.lastname: Thanyasiriwat
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Sraphet
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Whankaew
authors.affiliation: Rayong Field Crops Research Center, Ministry of Agriculture and Cooperatives, Rayong 21150, Thailand.
authors.forename: O
authors.initials: O
authors.lastname: Boonseng
authors.affiliation: Institute of Nuclear Agricultural Sciences, Key Laboratory of Zhejiang Province and Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Zhejiang University, Hua Jiachi Campus, Hangzhou 310029, China.
authors.forename: J
authors.initials: J
authors.lastname: Bao
authors.affiliation: Genomics Core-Facility, Southern Illinois University at Carbondale, Carbondle, IL 62901, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Lightfoot
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Pathumthani 12120, Thailand.|Center for Cassava Molecular Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: S
authors.initials: S
authors.lastname: Tangphatsornruang
authors.affiliation: Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand.|Center for Cassava Molecular Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors.forename: K
authors.initials: K
authors.lastname: Triwitayakorn
mesh_terms: D017343:Genes, Plant; D005838:Genotype; D002365:Manihot / Q000235:genetics* / Q000378:metabolism; D040641:Quantitative Trait Loci; D013213:Starch / Q000378:metabolism*; D014783:Viscosity
chemical_list: D013213:Starch
keywords: Gene linkage; glucosyl transferase; glycosyl hydrolase; glycosyl transferase; phenotypic variation; quantitative trait loci (QTL); starch quality