Karyological Study of Tea (Camellia sinensis L.) Genotypes in Iran

Tea (Camellia sinensis L.) is an important beverage crops containing caffeine worldwide. Releasing cultivars with high yield and quality demands knowledge about tea genetics and cytogenetics. Karyotypical study of nine tea genotypes was carried out using squash method on root tips. The best microscopic slides was first obtained using root tip of tea cuttings pretreated by α-bromo Naphthaline for 8 h، fixed by farmer solution and then stained with hematoxilin. Eight morphological traits were taken into consideration، each within three meiotic chromosomes using Micromeasure software. Analysis of variance showed significant differences (1%) among genotypes، chromosomes and the interactions، for all of the measured parameters. All studied teas were diploid and had 2n=2X=30 metacenteric and submetacenteric chromosomes. Total length of chromosomes ranged from 1. 10 to 4. 42 μm. Also، in terms of total length of chromosomes، genotypes 4 and 8 had the highest correlation and genotypes 2 and 9 had the lowest. Moreover some cytogenetic statistics was used in order estimate the karyotypic symmetry of genotypes. The results obtained showed that the genotypes 1 and 2 had the most asymmetric and genotypes 3 and 8 had the most symmetric، based on the TF%. Ordination based on principal components analysis (PCA) revealed presented that more than 97% of total diversity with two components was described. Centromeric index and long arm length had the most roles in the components، respectively. Cluster analysis using UPGMA method، also grouped the genotypes in four clusters and 100 promising clones were separated from the others، similar to result of PCA Bi-plot، relatively.