As. Parokonny et al., THE FATE OF RECOMBINANT CHROMOSOMES AND GENOME INTERACTION IN NICOTIANA ASYMMETRIC SOMATIC HYBRIDS AND THEIR SEXUAL PROGENY, Theoretical and Applied Genetics, 89(4), 1994, pp. 488-497
Genomic in-situ hybridization (GISH) was used to monitor the behaviour
of parental genomes, and the fate of intergenomic chromosome transloc
ations, through meiosis of plants regenerated from asymmetric somatic
hybrids between Nicotiana sylvestris and N. plumbaginifolia. Meiotic p
airing in the regenerants was exclusively between chromosomes or chrom
osome segments derived from the same species. Translocation (recombina
nt) chromosomes contained chromosome segments from both parental speci
es, and were detected at all stages of meiosis. They occasionally pair
ed with respectively homologous segments of N. sylvestris or N. plumba
ginifolia chromosomes. Within hybrid nuclei, the meiotic division of N
. plumbaginifolia lagged behind that of N. sylvestris. However, normal
and recombinant chromosomes were eventually incorporated into dyads a
nd tetrads, and the regenerants were partially pollen fertile. Recombi
nant chromosomes were transmitted through either male or female gamete
s, and were detected by GISH in sexual progeny obtained on selfing or
backcrossing the regenerants to N. sylvestris. A new recombinant chrom
osome in one plant of the first backcross generation provided evidence
of further chromosome rearrangements occurring at, or following, meio
sis in the original regenerant. This study demonstrates the stable inc
orporation of chromosome segments from one parental genome of an asymm
etric somatic hybrid into another, via intergenomic translocation, and
reveals their transmission to subsequent sexual progeny.