Karyotype, Meiotic Behavior, and Fertility of the Hybrid between the Tetraploid Allium wakegi Araki and the Amphidiploid (A. ascalonicum L.×A. fistulosum L.)

Abstract

In the somatic chromosome complement of the hybrid between the tetraploid Allium wakegi and the amphidiploid (A. ascalonicum×A. fistulosum) 16 pairs of chromosomescould be morphologically distinguished, and the karyotype was expressed by the following formula: K (_2n) =2(14V+J^(t)₁+J^T₂). At meiotic metaphase-I in the pollen mother cells of the hybrid 16 bivalents were regularly formed. At metaphase of pollen grain mitosis most of the pollen grains possessed the chromosome complements (K (_n) =14V+J^(t)₁+J^T₂) equivalent to the exact half of the somatic chromosome complement of thehybrid. Moreover, the hybrid was pollen fertile and had a good seed set. Therefore, it became clear that A. wakegi has the same genome constitution as that of the hybrid between A. ascalonicum and A. fistulosum. This indicates incontestably that A. wakegi is the synthetic species of these two species.