QTL analysis in a complex autopolyploid: Genetic control of sugar content in sugarcane
QTL analysis in a complex autopolyploid: Genetic control of sugar content in sugarcane
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DOI：
10.1101/gr.198801
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发表时间：
2001-12-01
期刊：
影响因子：
7
通讯作者：
Paterson, AH
中科院分区：
文献类型：
--
作者：
Ming, R;Liu, SC;Paterson, AH
自多倍体中的QTL定位由于一个位点上三个或更多等位基因的分离可能性和缺乏优先配对而变得复杂，然而显示单一分离比的多态等位基因子集可以用于定位QTL。在自多倍体Saccharum的两个种间群体中，通过31种不同的探针检测到36个非连锁位点与糖含量的变异之间存在显著相关。大多数QTL等位基因表现出与亲本表型一致的表型效应，但偶尔入侵的QTL也显示出从栽培品种中清除不利等位基因或从外源基因中渗入有价值等位基因的机会。同源染色体上的几个qtl似乎彼此对应——在这样的染色体区域，多剂量的有利“等位基因”产生递减的回报——这种负上位性可能有助于表型缓冲。从高糖基因型中发现的糖含量qtl少于从低糖基因型中发现的qtl，这可能表明许多有利的等位基因已经被先前的选择所固定，即在改良甘蔗中存在等位基因变异（qtl）的基因可能是控制糖含量的基因群体中的一个偏倚子集。将这些数据与之前在玉米中定位的突变和qtl进行比较，提示种子和生物质作物可能在碳水化合物沉积遗传变异方面具有部分重叠的基础。然而，许多qtl并不对应于已知的候选基因，这表明需要其他方法来分离营养组织高糖含量的遗传决定因素。
QTL mapping in autopolyploids is complicated by the possibility of segregation for three or more alleles at a locus and by a lack of preferential pairing, however the subset of polymorphic alleles that show simplex segregation ratios can be used to locate QTLs. In autopolyploid Saccharum, 36 significant associations between variation ill Sugar content and unlinked loci detected by 31 different probes were found in two interspecific F-1 populations. Most QTL alleles showed phenotypic effects consistent with the parental phenotypes, but occasional transgressive QTLs revealed opportunities to purge unfavorable alleles from cultivars or introgress valuable alleles from exotics. Several QTLs on homologous chromosomes appeared to correspond to one another-multiple doses of favorable 'alleles' at such chromosomal region(s) yielded diminishing returns-such negative epistasis may contribute to phenotypic buffering. Fewer sugar content QTLs were discovered from the highest-sugar genotype than from lower-sugar genotypes, perhaps suggesting that many favorable alleles have been fixed by prior selection, i.e. that the genes for which allelic variants (QTLs) persist in improved sugarcanes may be a biased subset of the population of genes controlling sugar content. Comparison of these data to mutations and QTLs previously mapped in maize hinted that seed and biomass crops may share a partly-overlapping basis for genetic variation in carbohydrate deposition. However, many QTLs do not correspond to known candidate genes, suggesting that other approaches will be necessary to isolate the genetic determinants of high sugar content of vegetative tissues.