Auger D L, Ream T S, Birchler J A
Division of Biological Sciences, University of Missouri, 117 Tucker Hall, Columbia, MO 65211-7400, USA.
Theor Appl Genet. 2004 Apr;108(6):1017-23. doi: 10.1007/s00122-003-1521-8. Epub 2003 Nov 21.
We conducted a test to detect if there is a heritable epigenetic component to hybrid vigor and/or inbreeding depression. The impetus for this work was a classical study of the effect of homozygosis on the expression of the maize red color ( r1) locus. It had been shown that maintaining R1 mottling alleles in the homozygous state over several generations produces a progressive decrease of their paternally imprinted expression. This effect is reversed by R1/r1 allele heterozygosity. If this behavior were characteristic of many regulatory genes, then such a phenomenon could contribute to inbreeding depression and heterosis. To examine this question, inbreds of Mo17 and B73 and the two reciprocally produced hybrids were crossed by Stock 6 to generate four classes of maternal haploids. The mature haploid plants were measured for several quantitative traits. If inbreeding depression results from an accumulating heritable effect that is reversed by the hybrid state, one would expect the haploids derived from the hybrids to perform better than those derived from the inbred lines. The hybrid-derived haploids did not exhibit greater average performance than the inbred-derived haploids. These data fail to support the hypothesis that inbreeding depression and heterosis have a metastable epigenetic component.
我们进行了一项测试，以检测杂种优势和/或近交衰退是否存在可遗传的表观遗传成分。这项工作的推动力来自一项关于纯合性对玉米红色（r1）位点表达影响的经典研究。研究表明，在几代人中保持R1斑驳等位基因处于纯合状态会导致其亲本印记表达逐渐下降。R1/r1等位基因杂合性可逆转这种效应。如果这种行为是许多调控基因的特征，那么这种现象可能导致近交衰退和杂种优势。为了研究这个问题，将Mo17和B73的自交系以及两个相互产生的杂种与Stock 6杂交，以产生四类母本单倍体。对成熟的单倍体植株进行了几个数量性状的测量。如果近交衰退是由一种可积累的遗传效应导致的，而这种效应在杂种状态下会被逆转，那么人们会预期来自杂种的单倍体比来自自交系的单倍体表现更好。来自杂种的单倍体并没有表现出比来自自交系的单倍体更好的平均表现。这些数据未能支持近交衰退和杂种优势具有亚稳态表观遗传成分这一假设。
