Detection of Somaclonal Variation in Tissue-Cultured Turkish Tea Genotypes Using SSR Markers
Abstract
Somaclonal variation is defined as genetic or epigenetic changes that occur in vitro between clonal regenerants and their corresponding donor plants. Genetic alterations involve cytogenetic abnormalities and changes in specific DNA sequences. Epigenetic changes refer to alterations in gene expression without modifying DNA sequences. Regardless of the mechanisms involved, somaclonal variation has been reported in several plant species. While the emergence of somaclonal variation in tissue culture negatively impacts the rapid production of clonal plants from elite varieties, it may also stimulate the creation of new horticultural plant genotypes. In the study presented here, the presence of somaclonal variation was evaluated in subculture explants of 12 new variety candidate tea genotypes obtained through selection and propagated via tissue culture. SSR-PCR reactions were conducted using 8 selected SSR markers previously constructed by Ma et al. (2014). Among these markers, TM586 (an SSR marker associated with EC, ECG, and EGCG groups) and TM560 (an ECG group SSR marker) exhibited high polymorphism. Notably, genotype 53KA10 (a white tea variety candidate) showed the highest number of somaclonal variations at the SSR locus.In the somaclonal variation analyses conducted on subculture explants of the 61HA52 genotype, varying degrees of polymorphism were observed in all markers except TM412 (an EGC group marker) and TM399 (an ECG group marker). Interestingly, among all the genotypes analyzed for somaclonal variation, only the 53ÇE184 genotype (a green tea variety candidate) exhibited genetic stability across all markers, with no somaclonal variation detected. Notably, the SSR marker TM399 (associated with Epicatechin gallate, or ECG) showed the lowest level of somaclonal variation in the regenerated explants. Based on the study data, it was suggested that tissue cultures should prioritize genotypes resistant to genetic alterations and stress conditions.
