National Institute of Genetics, 411, Mishima, Japan.
Theor Appl Genet. 1992 Jul;84(3-4):266-74. doi: 10.1007/BF00229481.
To assess the extent of differentiation into the Indica and Japonica types of Asian rice in its diversity center, we investigated landraces collected from the hilly areas of Nepal, Sikkim and Assam. We examined variations in four key characters and six isozyme loci known to be diagnostic for classifying Indica and Japonica types, and compared the results with those from a control set of rice cultivars representing the whole of Asia. The hill cultivars showed a high level of genetic diversity in key characters as well as in isozymes. A marked feature found in their character variation was the occurrence of various atypical cultivars that were intermediate between the Indica and Japonica types. With respect to isozymes, however, the hill cultivars could be classified mostly as either Indicas or Japonicas, although the patterns of allelic association were more random than in the control cultivars. Indica-Japonica variation in key characters and in isozymes corresponded well with each other in the controls, but not in the hill cultivars. This means that nonrandom association in characters as well as in genes (gametic disequilibrium) is not fully developed in the diversity center. Populations of hill cultivars were highly polymorphic genetically, but did not show a trend to Indica-Japonica differentiation within their populations. The process of Indica-Japonica differentiation is discussed in view of these observations.
为了评估亚洲稻种分化为籼稻和粳稻的程度，我们对来自尼泊尔、锡金和阿萨姆丘陵地区的地方品种进行了调查。我们研究了四个关键特征和六个同工酶基因座的变化，这些特征和基因座被认为是对籼稻和粳稻进行分类的诊断特征，并将结果与代表整个亚洲的一组水稻品种的对照结果进行了比较。丘陵地区的栽培品种在关键特征和同工酶方面表现出很高的遗传多样性。在它们的特征变化中，一个显著的特征是出现了各种介于籼稻和粳稻之间的非典型品种。然而，就同工酶而言，丘陵地区的栽培品种大多可以分为籼稻或粳稻，尽管等位基因关联的模式比对照品种更为随机。在对照品种中，关键特征和同工酶的籼稻-粳稻变异之间相互对应良好，但在丘陵地区的栽培品种中则不然。这意味着在多样性中心，特征和基因（配子不平衡）的非随机关联尚未完全形成。丘陵地区的栽培品种群体在遗传上具有高度多态性，但在其群体内没有表现出向籼稻-粳稻分化的趋势。根据这些观察结果，讨论了籼稻-粳稻分化的过程。
