Thanyasiriwat T, Sraphet S, Whankaew S, Boonseng O, Bao J, Lightfoot D A, Tangphatsornruang S, Triwitayakorn K
Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand.
Rayong Field Crops Research Center, Ministry of Agriculture and Cooperatives, Rayong 21150, Thailand.
Plant Biol (Stuttg). 2014 Jan;16(1):197-207. doi: 10.1111/plb.12022. Epub 2013 Apr 24.
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.
淀粉糊化粘度是木薯（Manihot esculenta Crantz）品种的一个重要品质性状。本文旨在鉴定与淀粉糊化粘度相关的基因座和候选基因。利用两个木薯品种Huay Bong 60和Hanatee杂交产生的100个F1作图群体株系，对七个糊化粘度参数进行了数量性状基因座（QTL）定位。淀粉样本取自2008年和2009年在罗勇种植以及2009年在泰国华富里府种植的木薯根。这些性状在F1后代中呈连续分布且存在超亲变异。从平均性状数据中鉴定出15个QTL，其对数似然比（LOD）值为2.77 - 13.01，表型变异解释率（PVE）为10.0 - 48.4%。此外，在不同环境中鉴定出48个QTL。LOD值范围为2.55 - 8.68，解释了6.6 - 43.7%的表型变异。这些基因座位于19个连锁群上。根据平均性状值，对糊化温度（PT）最重要的QTL（qPT.1LG1）显示出最大效应，具有最高的LOD值（13.01）和PVE（48.4%）。该QTL与在不同环境中鉴定出的PT和糊化时间（PTi）基因座共定位。在QTL峰值区域内鉴定出了候选基因。然而，编码糖基或葡萄糖基转移酶和水解酶家族的主要目标基因位于QTL峰值的外围。鉴定出的这些基因座可有效地应用于育种计划以改善木薯淀粉品质。应进一步研究候选基因的等位基因，以便更好地了解它们对淀粉品质性状的影响。
