Estimation of nuclear DNA content and its variation among Indian Tea accessions by flow cytometry

Nuclear DNA content and genome size variation among 36 Indian tea accessions were analyzed by flow cytometry. Initial standardization of protocols for isolation of nuclei, DNA staining and selection of an internal standard for tea accessions which have significantly high amount of phenolic secondary metabolites in their cytosol was carried out. Results obtained revealed that 2C DNA content of Indian tea is 7.46 pg which corresponds to 1C genome size of 3673 Mb. Inter accession variation in 2C DNA content was also observed among 35 diploid taxa ranging from 7.23 to 7.73 pg which was significant at 1% probability level. The 2C DNA content of triploid (UPASI 3) was observed to be 11.47 pg which is concurrent with the expected value. Results obtained showed that Assam and Cambod type tea accession have higher 2C DNA content of 7.73 pg whereas Assam Cambod hybrids and Assam China hybrids have reduction in DNA content with 2C amounts, 7.23 and 7.32 pg DNA respectively. The present study suggests that the species involved in origin of Indian tea must have differed in their genome sizes owing to significant inter accession variation in nuclear DNA content.