Fine mapping and allelic dosage effect of Hwc1, a complementary hybrid weakness gene in rice
Fine mapping and allelic dosage effect of Hwc1, a complementary hybrid weakness gene in rice
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DOI：
10.1007/s00122-007-0526-0
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发表时间：
2007-05-01
影响因子：
5.4
通讯作者：
Kuboyama, Tsutomu
中科院分区：
文献类型：
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作者：
Ichitani, Katsuyuki;Namigoshi, Keita;Kuboyama, Tsutomu
杂种弱势是许多植物物种中存在的生殖障碍。在水稻中，由两个互补基因Hwc 1和Hwc 2引起的杂种弱势已被广泛研究。然而，它们的基因产物和导致杂种弱势的分子机制仍然未知。我们进行了连锁分析Hwc 1，缩小到60 kb的兴趣区域，并确定了8个候选基因。在F-2群体中，其中Hwc 1和Hwc 2基因分离，植物可分为4类，根据各自的表型：严重型，半严重型，F-1型，和正常型。严重型植物表现出如此严重的症状，以至于它们只能产生微小的芽状结构;它们不能产生根。利用这两个基因紧密连锁的DNA标记进行的遗传分析表明，F-2植株的症状可以用Hwc 1和Hwc 2的基因型来解释。在同时具有Hwc 1和Hwc 2的植物中观察到弱点。在Hwc 1纯合子中，症状加重，出现重度或半重度植株。因此，Hwc 1基因具有剂量效应，为半显性基因。Hwc 2的剂量效应是可识别的，但不像Hwc 1那样严重。这些结果有助于阐明杂种弱势现象的发生机制以及各致病基因在杂种弱势中的作用。
Hybrid weakness is a reproductive barrier that is found in many plant species. In rice, the hybrid weakness caused by two complementary genes, Hwc1 and Hwc2, has been surveyed intensively. However, their gene products and the molecular mechanism that causes hybrid weakness have remained unknown. We performed linkage analyses of Hwc1, narrowed down the area of interest to 60 kb, and identified eight candidate genes. In the F-2 population, in which both Hwc1 and Hwc2 genes were segregated, plants were separable into four classes according to their respective phenotypes: severe type, semi-severe type, F-1 type, and normal type. Severe type plants show such severe symptoms that they could produce only tiny shoot-like structures; they were unable to generate roots. Genetic analyses using closely linked DNA markers of the two genes showed that the symptoms of the F-2 plants were explainable by the genotypes of Hwc1 and Hwc2. Weakness was observed in plants that have both Hwc1 and Hwc2. In Hwc1 homozygote, the symptoms worsened and severe type or semi-severe type plants appeared. Consequently, Hwc1 should have a gene dosage effect and be a semi-dominant gene. The dosage effect of Hwc2 was recognizable, but it was not so severe as that in Hwc1. These results are useful to elucidate the mechanism that causes the hybrid weakness phenomenon and the role of each causal gene in hybrid weakness.