Chromosomal Karyotype Differences of the Dark-Purple Tea Cultivar ‘Ziyan’ and Its Natural Hybrid Progenies

Abstract

‘Ziyan’ is a new variety of dark purple tender shoots tea tree which is rich in anthocyanins. ZY-1 and ZY-3 were two natural hybridized offspring of ‘Ziyan’, which were cultivated by single plant selection. ‘Ziyan’ is as the female parent, whereas the male parent has yet to be determined. In this study, we try to investigate cytological parameters of the three kinds of tea plants, and analyze the chromosomal karyotype differences among them. The results showed that the max arm ratio of ‘Ziyan’ was determined 2.50, and relative length was between 3.56% and 5.39%. The karyotype asymmetry index was 59.920%, and the karyotype formula was 2n=2x=30=22m (2SAT)+8sm. The max arm ratio of ZY-1 was 2.50, and relative length was between 4.80% and 8.69%. The karyotype asymmetry index was 60.307%, and the karyotype formula was 2n=2x=30=20m+10sm. The max arm ratio of ZY-3 was 2.77, and relative length was between 3.95% and 8.70%. The karyotype asymmetry index was 58.679%, which was lower than ‘Ziyan’ and ZY-3, and the karyotype formula was 2n=2x=30=24m+6sm. Although ‘Ziyan’ was significantly different from its two offspring, the karyotype characteristics of three varieties of tea plants were all type 2B. ‘Ziyan’ had a pair of satellites, but neither ZY-1 nor ZY-3 had a satellite. According to the karyotype asymmetry index and average arm ratio, the hybrid progeny ZY-3 was the most primitive, followed by the female parent ‘Ziyan’, while the hybrid progeny ZY-1 was the most evolutive.