| Summary: | 博士 === 國立臺灣大學 === 植物學研究所 === 83 === A triploid hybrid (2n=28) was produced from somatic hybridization
between haploid Nicotiana plumbaginifolia (n=10) and diploid N.
alata (2n=18). The somatic hybrid was subsequently crossed to di-
ploid N. alata. Among a total of 886 plants obtained from the
backcross, 41 contained 2n=19 chromosomes. Three of these plants
lost one chromosome during maintenance in culture and one was
found later to be a trisomic of N. alata. Grouping of monosomic
addition plants, each containing a 2n chromosome complement of
N. alata and one chromosome of N. plumbaginifolia, based on mor-
phological characteristics and identification of the N. plumbagi-
nifolia chromosome were difficult. Gross chromosome abberations,
such as deletions and rearrangements, and changes in RFLP pat-
terns, such as loss ofparental DNA bands and appearance of new
bands, occurred in the somatic hybrid as well as chromosome addi-
tion plants. Thesewere attributed to incompatibility between the
parental genomes and crossing over during meiosis in the hybrid.
The latter phe-nomenon was suggested by the frequent occurrence
of multivalents in microsporocytes of the somatic hybrid, and was
confirmed by the observation of intergenomic chromosome rearran-
gementsin monosomic addition plants using genomic in situ hybri-
dization.
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