Chloroplast and Mitochondrial DNA Assay in Solving Issues Related to the Taxonomy of Beveragial Tea Clones

Despite utilization of multidisciplinary approaches including nuclear DNA assay, the taxonomy of world beveragial tea clones is still contentious and elusive. They are considered to be constituted by 1–34 Camellia species. In the present study physical mapping of the chloroplast genome in combination with six restriction endonucleases, and restriction fragment length polymorphism of the six (nad5, nad3, atpA, rrn26, coxI and coxIII) mitochondrial genes in combination with six restriction endonucleases was analysed in 50 divergent beveragial tea clones. In chloroplast genomes, only six out of the 230 restriction sites identified by 186 enzyme-probe combinations exhibited variation among the tea clones. The six mutations were site mutations. The 36 enzyme-probe combinations in mitochondrial genome yielded 122 fragments that hybridized to the probe. Nine combinations generated monomorphic profiles across all the 50 clones while remaining 27 combinations produced 94 (77.0 %) polymorphic bands in 20 clones. To understand genetic relationships among the clones, Jaccard’s similarity coefficient and UPGMA clustering algorithm were applied to the cpDNA and mtDNA data. Strong correlation was observed between the two data. Both data grouped the clones into three clusters with very little or no heterogeneity within the clones forming two clusters. The present study makes it abundantly clear that the beveragial tea is not constituted by 34 species. In fact, the origin of the present day beveragial tea clones, cultivated in ~30 countries, lies in the origin of India hybrid tea as a result of extensive hybridization between closely related Assam (Camellia assamica ssp assamica) type and China (C. sinensis) type germplasm when the seeds of the latter were introduced in north east India.