Chromosome analysis of tea plant (Camellia sinensis) and ornamental camellia (Camellia japonica)

Chromosome analysis of tea plant (Camellia sinensis), an important commercial crop used to prepare beverages throughout the world, was conducted using fluorescence in situ hybridization (FISH) and chromosome image analyzing system IV (CHIAS IV) software. Chromosomes of C. japonica, a popular woody plant used as an ornamental tree and an important breeding resource for tea plants, were used for comparison with C. sinensis. Both C. sinensis and C. japonica comprised 30 chromosomes. The 5S rDNA, a fundamental repeat sequence and a landmark for FISH, was used for Camellia karyotyping. We observed one 5S rDNA locus on two chromosomes in both the species and confirmed the presence of bivalents in the meiotic cells of interspecific hybrids between C. japonica and C. sinensis. These results suggest that the two species have homoeologous chromosomes. C. sinensis chromosomes were analyzed using CHIAS IV, which performs quantitative karyotyping. This is the first report on the karyotyping of the Japanese tea plant C. sinensis by FISH and quantitative image analysis using CHIAS IV. This report will accelerate the use of cytological and genetic linkage map analysis in tea breeding.