FREQUENCY AND SPECTRUM OF CHROMOSOMAL ABERRATIONS IN VARIETIES AND MUTANT FORMS OF <i>Camellia sinensis</i> (L.) Kuntze UNDER SPONTANEOUS MUTAGENESIS
In natural environment, tea Camellia sinensis (L.) Kuntze plants show high adaptability, which allows selecting valuable forms for breeding. An increase of genetic variability can be induced by several environmental factors, i.e. incoming radiation, temperature shocks, pesticides, fertilizers and so on. To estimate the variability, we studied the chromosomal aberrations in Kolkhida variety (as a standard on the yield and quality parameters), in Kimyn variety (both are large-leaved Chinese sort), in so-called «local population» (a mix of Chinese, Indian and Japanese sorts), and in their mutant forms with varying phenotype (the plants with deviations in leaf size, shape, coloration, blistering, and those fully modified in appearance). Plants were grown on commercial plantations in Gudauta, Sukhumi and Ochamchir regions of Abkhazia. The seeds harvested in September and October were germinated in thermostatic conditions at 27-30 °С. To examine the patterns of chromosomal abnormalities, only the seeds reproduced in Sukhumi region were used as here was the highest frequency of somatic changes (3.95±0.20 % comparing to the lowest rate of 2.00±0.03 % in Ochamchir region), and the frequency of fully modified plants in Sukhumi region has reached 0.1 %. In root meristem cells of Kimyn variety, the highest rate of chromosomal rearrangements (2.18±0.20 to 5.92±0.47 % depending on the location) was detected in mitotic anaphases I (2501 to 5580 revised). The significant differences were indicated in Kimyn variety (Р < 0.001) and in the local population (Р < 0.05). More mutable Kimyn variety also showed a wider range of the chromosomal abnormalities if compared to Kolkhida variety. In Kolkhida variety, single and double fragments were observed, while in Kimyn variety the single and double bridges were also found. The Kimyn variety is considered perspective as a parent form for breeding. All studied varieties were diploids (2 n = 30). For all compared varieties and habitats a frequency of somatic mutations correlated positively to chromosomal abnormalities.