Genetic diversity among tea cultivars from China, Japan and Kenya revealed by ISSR markers and its implication for parental selection in tea breeding programmes

Abstract

Tea plant [Camellia sinensis (L.) O. Kuntze] is an important beverage crop in the world. In recent years many clonal tea cultivars have been released, and they play major roles in improving the production and quality of tea. It is important to understand the genetic diversity and relatedness of these cultivars to avoid inbreeding and narrow genetic basis in future tea breeding. In the present study, genetic diversity and relationship of 48 tea cultivars from China, Japan and Kenya were evaluated by inter-simple sequence repeat (ISSR) markers. A total of 382 ISSR bands were scored, of which 381 (99.7%) were polymorphic. The ISSR primers showed high ability to distinguish between tea cultivars according to their high Resolving Power (R P ) with an average of 7.4. The mean of NeiÕs gene diversity (H) and ShannonÕs information index (I) were 0.22 and 0.35, respectively. More abundant diversity was revealed among cultivars in China than those in Japan and Kenya. Within Chinese populations, the level of diversity in east China was higher than that in other regions. The coefficient of genetic differentiation (G ST ) was 0.202, which indicates a high degree of genetic variation within populations. This result was further confirmed by analysis of molecular variance, which revealed the variance component within the populations (92.07%) was obviously larger than that among populations (7.93%). The level of gene flow (N m ) was estimated to be 2.0. This could be explained by frequent natural crosspollination and seed dispersal among tea populations. The pairwise similarity coefficient between the cultivars varied from 0.162 to 0.538. A dendrogram of 48 tea cultivars was constructed where all the tested cultivars were divided into two groups. Our data show that the genetic relationship among tea cultivars can be determined by the ISSR markers. This will provide valuable information to assist parental selection in current and future tea breeding programmes.

Development and characterization of single nucleotide polymorphism markers in Camellia sinensis (Theaceae)

“…The dendrogram was divided into 2 groups (Figure 3). All of the sinensis varieties were clustered into group A, which was consistent with previous findings by AFLP (Balasaravanan et al, 2003) and ISSR (Yao et al, 2008) markers. Thus, these SNPs are effective for genetic distance estimation.…”

AFLP-Based Genetic Diversity Assessment of Commercially Important Tea Germplasm in India

“…A further explanation for these genetic diversity results could be that tea populations cultivated at the national level are derived from a similar gene pool and share a common genetic background. Lack of genetic differentiation among the populations has also been reported in earlier studies of tea (Wachira et al 1995(Wachira et al , 2001Paul et al 1997;Yao et al 2008;Ohsako et al 2008). Exchange of genetic material in cultivated crop species in most of the cases is dictated more by human intervention than by natural factors.…”

“…In the past decade or so, many efforts have been made to assess the genetic diversity of Indian tea germplasm at the phenotypic (Barua 1963;Banerjee 1992;Das 2001), cytogenetic (Bezbaruah 1971), biochemical (Saravanan et al 2005, and molecular levels (Paul et al 1997;Mondal 2002;Wachira et al 2001;Balasaravanan et al 2003;Singh and Ahuja 2006;Karthigeyan et al 2008;Sharma et al 2009). Numerous genetic diversity studies have also been conducted on tea germplasm in other regions of the world, using various molecular marker techniques (Kaundun et al 2000;Kaundun and Matsumoto 2002;Chen and Yamaguchi 2005;Matsumoto et al 2004;Ohsako et al 2008;Yao et al 2008). Most of these investigations carried out nationally or internationally, however, suffer from an important lacuna: either small sample size or accessions restricted to a particular region.…”

Artificial neural networks as a tool for plant identification: a case study on Vietnamese tea accessions

“…Lastly, PH1 is an Assamic variety, known as the first created by the Viet Nam Tea Research Institute more than 20 years ago; it has been propagated by seed during the years, causing a massive hybridization with some correspondence in morphological features with Chinese type. In general, we can assess that both the morphological analysis and the creation of a neural network were able to characterize, univocally recognize and associate most of the accessions in the correct clusters without a molecular analysis, as previously done by Mondal (2002) and Yao et al (2008). For example, Mondal (2002) analyzed some cultivars belonging to the three main groups of tea (Chinese, Assamic and Cambodian) through the simple sequence repeat anchored PCR (SSR-anchored PCR).…”