2010 Volume 9 Issue 1 Pages 7-12
We studied the origin of Keraji (Citrus keraji hort. ex Tanaka), which is a local cultivar mainly grown on Kikaijima island located on the east side of Amami-oshima, Kagoshima prefecture. The proportion of common bands was calculated based on the results of inter simple sequence repeat (ISSR) analysis. For Keraji, that value was highest for Kunenbo (C. nobilis Lour.) (0.823), followed by Kikaimikan (C. keraji hort. ex Tanaka) (0.688). Of the 16 polymorphic markers that appeared in Keraji, all bands were shared with Kunenbo and/or Kikaimikan, and no extra bands were detected in Keraji. Therefore we can assume that Keraji originated from Kunenbo and Kikaimikan. Since Keraji, Kunenbo and Kikaimikan always showed identical banding patterns on chloroplast DNA analysis, those three accessions were not distinguished from each other. Since both self-incompatible Keraji and Kikaimikan were cross-incompatible on reciprocal crossing, the incompatible genotype of those two accessions was considered identical. However, cross-incompatibility was not found between those two accessions and self-incompatible Kunenbo. When Kikaimikan and Kunenbo, which are both candidates for parental accessions of Keraji, carry the same incompatible gene, Keraji and its pollen parent are cross incompatible. In accordance with this theory, there is a possibility that Keraji originated from Kunenbo and Kikaimikan as the seed and pollen parent, respectively.
