Usage of morphological and ISSR markers for investigation of Tea genotypes

Tea (Camellia sinensis (L.) O. Kuntze) is one of the most important crops in nourth of Iran. Todays, many tea plants are being destroyed for various reasons, so having information about their genetics is helpful in designing breeding programs to reach appropriate plants for specific purposes. Therefore, in this research, the genetic diversity of some tea genotypes were identified in major cultivation regions of this crop in nourth of Iran with comparison by eight imported clones.

In this study genetic diversity of 42 tea plants were investigated by useing of two morphological and ISSR markers. Morphological study was performed by descriptor that registered form for tea and 31 traits were checked out. After selecting young and well expanded leaves, their genomic DNA were extracted and 10 ISSR primer were used for investigation of genetic relationships between 42 tea genotypes. Collected data was analysed by Euclidean distances for Morphological markers and SM similarity coefficient for ISSR and clusters were designed based on UPGMA algorithm. PCA anayesd were done by SPSS.

Comparative analysis on 31 morphological characteristics in tea genotypes and clone showed moderate variations and showed a narrow range. In cluster analysis at a difference of 6.6, the samples were divided into six groups; the main group consisted of the sixth group, which contained 88% of the samples. The results of PCA on morphological characters showed that the first, five principal components accounted for 54.21% of the total variance. Used of 10 ISSR primers produced 92 scorable bands that 72 of them were showed polymorphism pattern (78.26%). The PIC analysis showed ranging from 0.43 to 0.50. cophenetic test showed that SM similarity coefficient and UPGMA algorithm was the best for cluster analyses. According to ISSR data calculated similarity were range between 0.28- 0.93. In cluster analyses, samples at similarity 0.55 divided to four group that fourth group was the main created group and coverd 66.66% of samples. The results of PCA on ISSR data showed that the first, five principal components accounted for 72.98% of the total variance.

A significant variability was observed in the selected tea genotypes at morphological and molecular levels. Morphological study showed that distribution of tea plant in the past, although based on desirable characteristics, but due to the limited initial source of this plant, there is little variation among the genotypes of the regions. In relation to the ISSR marker, the polymorphism percentage and t polymorphic information content from the primers used in this study indicate the ability of these markers to differentiate the tea genotypes. From these results it could be understood that these series of characters and primers can distinguish genetic differences very well. Using these markers, genetic variation was observed between the genotypes of tea, but this diversity was not such as to be able to disrupt the genotypes of different regions. It seems that this separation could be achieved by increasing the number of primer combinations and using other markers such as SSR and SNP. Also, the results of this study showed that Iranian tea genotypes have high genetic variation because they are mostly reproduced sexually.