Variation in the Nucleolar Organizing Regions in Japanese Garden Iris and its Wild Forms (Iris ensata Thunb.)

Abstract

Variation in the NORs in nine eu-diploid and two aneuploid cultivars and two wild forms of Iris ensata was examined by a silver-staining method. Although the number of NOR-bearing chromosomes at somatic metaphase ranged from 3 to 6 among the cultivars and wild forms, 4 NOR-bearing chromosomes which were recognized in the wild form “Normal type” accounted for eight cultivars. Therefore, this number is regarded as the basic one for I. ensata. The numerical variations of NOR-bearing chromosomes might be caused by the structural changes of chromosomes such as translocations or deletions. In addition, the conclusive evidence for a translocation came from a NOR-bearing chromosome with two NOR-bands observed in the cultivar “Shakyo”.