Chromosome relationship between Camellia japonica and Camellia reticulata revealed by genomic in situ hybridization

Abstract

Relationships between Camellia. japonica and C. reticulata were studied to assess whether C. reticulata inherited the genome complements from C. japonica. Genomic in situ hybridization (GISH) was used to get the hybridization signalpatterns in mitotic interphase nuclei and metaphase chromosomes of three polyploid types in root-tip cells in C. reticulata using the whole genomic DNA of C. japonica as probe. Most of the hybridization signals were located at the terminal region of the chromosomes, whereas weak signals were found in whole parts of chromosomes. Numbers of hybridization signals in interphase nuclei had a tendency that higher numbers were correlated with higher ploid levels, however, no correlation between the hybridization signals and the ploidy level was seen in the metaphase chromosomes in C. reticulata. The results confirmed that the polyploids of C. reticulata were allotetraploid and allohexaploid. The results also showed that C. reticulata and C. japonica were closely related to each other, and C. japonica had partly contributed to the origin of the polyploid C. reticulata.