Genetic differentiation in three buckwheat(Fagopyrum) species with the distinct reproductive systems and the origin of cultivated buckwheat species

对3种荞麦(Fagopyrum)在世界各地的分布进行了调查，从世界各地的普通荞麦、普通荞麦和多年生荞麦中分别采集了148个、88个和29个样本。通过对这些样品进行等位酶变异的电泳分析和形态性状的比较分析，得出以下结论：(1)普通荞麦栽培群体在群体中保持的等位酶变异比其他异交植物的平均水平高得多。中国南部和印度东部的种群变异最大，这一地区可能是变异的中心。然而，没有发现等位酶频率的关键地理差异；只有在分布的边缘，即印度和南欧的库马恩和克什米尔，才发现微小的差异。观察到的等位酶频率和形态变异的一致性可以用大群体和随机的…来解释随着种群间充分的基因流动，交配效率更高。(2)来自喜马拉雅地区、中国和欧洲的另一个栽培荞麦品种塔塔里荞麦的样品在形态上有很大的差异，但它们显示出有限的等位酶差异，这与我们从该物种自花授粉的本质上认为种群间存在较大差异的预期背道而驰。中国的多年生荞麦为二倍体，而分布于泰国、印度和尼泊尔的荞麦为四倍体。自然种群主要以营养繁殖为主。然而，自然群体具有与普通荞麦相同的等位酶变异，这表明种子繁殖在保持变异中起着重要作用。因此，我们对三个荞麦品种的等位酶数量和形态变异进行了评估，并对维持这些变异的机制有了部分了解。明确了荞麦栽培变异丰富的区域、发生局部分化的区域和推广过程。较少

A world-wide survey of the distribution of three buckwheat(Fagopyrum) spcies was conducted and 148, 88 and 29 samples were collected in common buckwheat, tatary buckwheat and perennial buckwheat, respectively, from various parts of the world. Electrophoretic assay of allozyme variability and a comparative analysis of morphological traits on these samples led to the following remarks.(1) Cultivated populations of common buckwheatmaintain much more allozyme variability in a population than the average of other outcrossing plant species. The populations from southern China and eastern India had most variability; this area may be the center of variability. However, no crucial geographical differentiation of allozyme fequencies was detected; minor differentiations were found only at the margins of distribution, i.e. Kumaun and Kashmir in India and southern Europe. The observed uniformity of allozyme frequencies and morphological traitsmay be interpreted by large population sized and randomn … More ess of mating along with the sufficient gene flow between populations. The traces of the spreading processes of buckwheat cultivation could be seen in the geographical changes or losses of allozymes.(2) The samples of tatary buckwheat, the other cultivated bucukwheat species, from the Himalayan region, China and Europe were quite variable in morphology, yet they showed limitted differences in allozymes, in contradiction to our expectation of great variability between populations from the nature of self-pollination of this species. At present, no reasonable interpreation is available for this.(3) The perennial buckwheat samples from China were revealed to be diploid, while those distributed in Thailand, India and Nepal were tetraploid. The natural populations are predominantly reproduced vegetatively. However, the natural populations had as much allozyme variability as common buckwheat, indicating that seed reproduction plays an important role in maintenance of variability.Thus, the amount of allozyme and morphological variability was assessed for three buckwheat species, and the mechanisms that maintain those variability were partly understood. The variability-rich regions, the area where local differentiation took places, and the spreading processes of buckwheat cultivation have been clarified. Less