Okogbenin E, Fregene M
International Center for Tropical Agriculture, CIAT Km 17, Recta Cali-Palmira, AA6713, Cali, Colombia.
Theor Appl Genet. 2003 Nov;107(8):1452-62. doi: 10.1007/s00122-003-1383-0. Epub 2003 Aug 9.
An attempt was made to identify quantitative trait loci (QTLs) for several productivity and plant architecture traits in a full-sib progeny of 144 individuals from two non-inbred parents in cassava. A molecular linkage map of this cross constructed previously with over 250 markers was the source of molecular markers. The progeny were grown under field conditions at two locations (Palmira and Quilichao) in Colombia and evaluated in 2 years (1998 and 1999) for architecture and productivity traits. Architecture traits evaluated were plant height (PH), branching height (BH), branching levels (BL), branching index (BI), stem portion with leaves (SPL) and leaf area index (LAI). Productivity traits were those related to total dry matter production and distribution, namely fresh root yield (FRY), fresh shoot yield (FSY), harvest index (HI) and the number of storage roots (NR). Phenotypic evaluation of the traits in this population revealed continuous variation for all traits. Broad-sense heritability estimates, ranged from 36% (for NR) to 94% (for BH). Several significant phenotypic correlations were observed between architecture and productivity traits. Primary QTLs, using the single-QTL model, and secondary QTLs, by a primary QTL interaction model, were detected by interval mapping. A total of 30 primary QTLs and 84 secondary QTLs were detected. We identified 35% of detected QTLs in two or more trials, the other QTLs were environment-specific. These results underscore the significant genotype x environment interactions found for most of the traits. Several genomic segments affecting multiple traits were identified and were in agreement with correlation among traits. All QTLs identified for FRY were found associated with either component traits of productivity or architecture traits. This study suggests that QTLs for plant architecture can be used to improve productivity. However an exhaustive search and analysis of QTLs controlling architecture is required before marker-assisted selection (MAS) for increasing productivity can be initiated.
人们尝试在木薯中，对来自两个非自交亲本的144个个体的全同胞后代中的几个生产力和株型性状进行数量性状位点（QTL）鉴定。先前构建的、含有250多个标记的该杂交组合分子连锁图谱是分子标记的来源。这些后代在哥伦比亚的两个地点（帕尔米拉和基利乔）的田间条件下种植，并在两年（1998年和1999年）内对其株型和生产力性状进行评估。评估的株型性状包括株高（PH）、分枝高度（BH）、分枝层数（BL）、分枝指数（BI）、带叶茎段（SPL）和叶面积指数（LAI）。生产力性状是那些与总干物质生产和分配相关的性状，即鲜根产量（FRY）、鲜茎产量（FSY）、收获指数（HI）和贮藏根数量（NR）。对该群体中这些性状的表型评估显示，所有性状均呈现连续变异。广义遗传力估计值范围从36%（NR）到94%（BH）。在株型和生产力性状之间观察到了几个显著的表型相关性。通过区间作图，使用单QTL模型检测到了主QTL，通过主QTL互作模型检测到了次QTL。共检测到30个主QTL和84个次QTL。我们在两个或更多试验中鉴定出了35%的检测到的QTL，其他QTL是环境特异性的。这些结果强调了大多数性状中存在显著的基因型×环境互作。鉴定出了几个影响多个性状的基因组片段，这与性状间的相关性一致。所有鉴定出的与FRY相关的QTL都与生产力的组成性状或株型性状相关。这项研究表明，株型QTL可用于提高生产力。然而，在开始用于提高生产力的标记辅助选择（MAS）之前，需要对控制株型的QTL进行详尽的搜索和分析。
