Chromosome relationships in allopolyploid species are either homologous, homoeologous, or non-homologous. To discern the behavior of chromosomes in each of these relationships, we produced double monosomic addition lines (DMAs) of wheat carrying one Leymus racemosus chromosome and one Leymus mollis chromosome in different combinations, and observed the Leymus chromosomes in meiosis by differential genomic in situ hybridization. First we observed the distribution of these alien chromosomes in tetrad cells and measured their homology by an index of their interaction. Values differed greatly among DMAs. We observed prophase to anaphase cells of meiotic division I and elucidated the differences in homology through chromosome behavior in meiosis. A line carrying chromosomes [l^r] of L. racemosus and [M^m] of L. mollis formed bivalents in about half of the prophase cells, but these chromosomes became univalent in metaphase because of a lack of chiasmata, and segregated normally to each pole. The chromosomes in the other half of the prophase cells did not associate and behaved randomly from anaphase to tetrads. The DMAs proved useful in studying the homology of chromosomes.

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A total of 111 horticultural cultivars of Farfugium japonicum were studied cytologically and described morphologically for the first time. All 111 cultivars with various unusual morphologies, such as dwarf, rumpled leaves, etc., had 2n=60 chromosomes, which was the same number as in wild plants. Only one individual obtained by tissue culture of the cultivar ‘Yukibeni-botan’ had exceptional chromosome number with 2n=59. In 14 cultivars with 2n=60 chromosomes examined, no abnormal chromosome behavior was observed through the microsporogenesis, and at the meiotic metaphase I, 30 bivalents were observed. Among the flowered 96 individuals in 95 cultivars, seven individuals had no pollen grains, and those having atrophied head, such as “SHISHI” and “KURUMA”, showed relatively low pollen stainabilities, 48.3 and 23.4% in average, respectively, whereas the other cultivars had high stainability (91.3% in average). The 2n=59 somaclonal variant of the cultivar ‘Yukibeni-botan’ showed the lowest stainability (0.3%). These results indicate that horticultural cultivars of F. japonicum are stable diploids from the cytogenetical viewpoint, and that the morphological diversity in the cultivars should not be ascribed to the numerical changes of chromosomes but must have been caused by mutation of gene(s) responsible for morphogenesis.

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Phytolacca acinosa (Phytolaccaceae) is cytologically worked out for the first time from Tangmarg area of Kashmir, India. The tetraploid chromosome count of 2n=36 from the present study represents a new cytotype for the species from India. The plant shows the case of an autotetraploid as it is characterised by multivalent formation during meiosis. A total of 55.89% of the chromosomes were involved in multivalent formation (quadrivalent and trivalents) while as 12.15% remained as univalents. These multivalents caused meiotic irregularities such as unoriented chromosomes, laggards and bridges at different stages of meiosis. Microsporogenesis was also abnormal ultimately resulting in reduced pollen fertility 46.78% and lead to the formation of heterogenous sized pollen grains.

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