ESTIMATION OF COEFFICIENT OF COANCESTRY USING MOLECULAR MARKERS IN MAIZE
ESTIMATION OF COEFFICIENT OF COANCESTRY USING MOLECULAR MARKERS IN MAIZE
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DOI：
10.1007/bf00215047
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发表时间：
1993-02-01
影响因子：
5.4
通讯作者：
BERNARDO, R
中科院分区：
文献类型：
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作者：
BERNARDO, R
个体A和B之间的共祖先系数（f（AB））是遗传关系的经典度量。f（AB）由系谱记录确定，并且是A和B中相同基因座上的随机等位基因是相同祖先等位基因的拷贝或血统相同的概率（ibd）。最近，A和B之间共有的分子标记变体的比例（S（AB））已被用于测量遗传关系。但是S（AB）是f（AB）的一个向上偏估计，特别是在距离相关的线之间。比较了f（AB）、S（AB）和校正（以消除偏倚）后的分子标记相似性估计值（f（AB）M）。以爱荷华州硬茎合成（BSSS）玉米（Zea mays L.）群体，以及4个非BSSS系。f（AB）M = [S（AB）-1/2（delta（A.）+ δ（B.））]/ [1-1/2（delta（A.）+ δ（B.））]，其中delta（A）。(orδ（B.））是近交系A（或近交系B）和非BSSS系之间共有的RFLP变体的平均比例。253个BSSS组合的平均f（AB）为0.212，平均S（AB）为0.397。平均f（AB）M为0.162，表明有效地消除了S（AB）中的向上偏差。在76.3%的比较中，S（AB）和f（AB）存在显著差异（α = 0.05），而24.9%的f（AB）M值与f（AB）存在显著差异。后者的结果表明，选择和/或漂移存在于近交系的发展和f（AB）可能不是一个准确的衡量两个线之间的ibd等位基因的真实比例。基于S（AB）和f（AB）M的聚类分析根据系谱对品系进行分组，但也有几个例外。在设定基于S（AB）的最小距离进行品种保护时，必须考虑到不相关品系之间存在共享的分子标记变异。在简化的条件下，超过250个分子标记位点是必要的，以获得足够精确的估计系数的共祖先使用分子标记。
The coefficient of coancestry (f(AB)) between individuals A and B is the classical measure of genetic relationship. f(AB) is determined from pedigree records and is the probability that random alleles at the same locus in A and B are copies of the same ancestral allele or identical by descent (ibd). Recently, the proportion of molecular marker variants shared between A and B (S(AB)) has been used to measure genetic relationship. But S(AB) is an upwardly-biased estimator of f(AB), especially between distantly-related lines. f(AB), S(AB), and adjusted (to remove bias) estimates of molecular marker similarity (f(AB)M) were compared. RFLP banding patterns at 46 probe-restriction enzyme combinations were obtained for 23 maize inbred lines derived from the Iowa Stiff Stalk Synthetic (BSSS) maize (Zea mays L.) population, and for 4 non-BSSS lines. f(AB)M was estimated as f(AB)M = [S(AB)-1/2(delta(A.) + delta(B.))]/[1-1/2(delta(A.) + delta(B.))], where delta(A). (or delta(B.)) was the average proportion of RFLP variants shared between inbred A (or inbred B) and the non-BSSS lines. The average f(AB) among 253 pair-wise combinations of BSSS lines was 0.212, whereas the average S(AB) was 0.397. The average f(AB)M was 0.162, indicating that the upward bias in S(AB) was effectively removed. S(AB) and f(AB) were significantly different (alpha = 0.05) in 76.3% of the comparisons, whereas 24.9% of the f(AB)M values differed significantly from f(AB). The latter result suggests that selection and/or drift were present during inbred line development and that f(AB) may not be an accurate measure of the true proportion of ibd alleles between two lines. Cluster analyses based on S(AB) and f(AB)M grouped lines according to pedigree, although several exceptions were noted. The presence of shared molecular marker variants between unrelated lines must be considered when setting S(AB)-based minimum distances for varietal protection. Under simplified conditions, more than 250 molecular marker loci are necessary to obtain sufficiently precise estimates of coefficient of coancestry using molecular markers.