The structural comparison of somatic chromosomes of 13 species and one variety of Lachenalia (Liliaceae) that contained the chromosome numbers either of 2n=14 or 2n=16 (the basic chromosome numbers may be x=7 or x=8) was performed by DAPI staining and fluorescence in situ hybridization (FISH) using 5S rDNA and 18S rDNA probes. The five taxa which had the chromosome number of 2n=16 (x=8) displayed similar characters and close relationships to each other. Eight species and one variety which had the chromosome number of 2n=14 (x=7) showed a variety of patterns. The cases were suggested as traces of additions to the 18S rDNA region, translocations of chromosomes and hereditary exchanges among the taxa with x=7 and a taxa with x=8. It was suggested that the chromosome diversity in Lachenalia, especially in the taxa of basic chromosome number of x=7, was resulting a speciation reflected by hereditary influences between the taxa which had other patterns of chromosome structures.

View full abstract

Artificial crosses between the Japanese, octoploid Chrysanthemum shiwogiku Kitamura and Chinese, hexaploid C. vestitum (both Asteraceae-Anthemideae) produced 48 hybrids out of 181 germinated plants grown up to the mature stage. The hybrids showed more or less intermediate in morphological character between the two parents and somewhat more close to C. vestitum in white-color ligule flowers inherited. The chromosome numbers in 19 out of 48 hybrids studied varied from 2n=63 to 81 with various aneuploids and some individuals showed very small-sized chromosomes perhaps due to B-chromosomes of which undetected parentage had produced. The hybrid plants might be able to produce back-cross progenies after hybridization with C. vestitum as a paternal parents, as well as could hybridize with sister plants of the F₁ hybrids as ovule and pollen donors.

View full abstract

Resting nuclei, the mitotic prophase and metaphase chromosomes in five species of Lycopus were compared: The resting nuclei were commonly of the complex chromocenter type and the mitotic prophase chromosomes were of the proximal type. Lycopus ramosissimus, L. maackianus, L. unifloru and L. europaeus showed commonly the chromosome number of 2n=22, while L. lucidus showed 2n=66. The chromosome number of 2n=66 in L. lucidus and that of 2n=22 in L. ramosissimus were reported here for the first time, and that of 2n=22 in L. maackianus, L. uniflorus and L. europaeus verified the previous reports. Four species of the genus with 2n=22 could be all diploid and one species with 2n=66 could be hexaploid if the basic chromosome numbers x=11 was accepted.

View full abstract