Browsing by Author "Bharathi, M."

Now showing 1 - 5 of 5
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    DNA polymorphism among coconut (Cocos nucifera L.) cultivars and reciprocal cross derivatives differing in drought tolerance
    (2004-12) Manimekalai, R.; Nagarajan, P.; Bharathi, M.; Naresh Kumar, S.
    Coconut seedlings of Laccadive Ordinary Tall (LCT). Gangabondam Green Dwarf (GBGD) and their reciprocal cross combinations were analysed by molecular markers viz. Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR). These seedlings were evaluated for water stress tolerance based on leaf water potential measured during stress and non- stress periods. Thc leaf water potential decreased during stress period. The differences among the individuals for leaf water poteniial during stress were not significant. The molecular markers revealed the genetic structure of the cultivars and derivatives clearly. In the dendrogram. individuals of GBGD and GBGD X LCT formed one cluster and LCT and LCT X GBGD formed another cluster. The individuals of LCT and LCT X GBGD showed variation among themselves and they were scattered in the principal co-ordinate plot. Even though the parents are same. the reciprocal cross derivatives behaved differently for leaf water potential and showed polymorphism at DNA level. When the dwarf palm was used as female parent, the F, s were similar to female parent in their banding pattern.
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    Genetic variation of selected progney lines of coconut(cocos nucifera.L) based on simple sequence repeat markers
    (2005) Manimekalai, R.; Nagarajan, P.; Bharathi, M.; Karun, A.; Kumar, S.N.; Kumaran, P.M.
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    Isolation and characterization of WRKY genes in coconut (Cocos nucifera L.)
    (2006) Rajesh, M.K.; Bharathi, M.; Nagarajan, P.
    WRKY proteins are plant-specific transcriptional factors associated with regulation of defense responses to both biotic and abiotic stresses. in the present study, degenerate PCR primers were designed to the highly conserved WRKY DNA binding domain and these were used to isolate putative WRKY genes from coconut. Six DNA fragments were isolated using five pairs of degenerate primers and these Were cloned. Sequencing of these cloned fragments was done and their amino acid sequences deduced. Homology search of the deduced amino acid sequences against non-redundant GenBank protein database revealed significant sequence similarity of two of the cloned fragments to known WRK Y genes. The other four cloned fragments showed homology to known stress responsive genes. Cluster analysis based on neighbour-joining method was carried out using the putative coconut WRKY genes with other known WRKY genes. These results demonstrate that PCR amplification with appropriately designed degenerate primers is an efficient approach for cloning WRKY genes.
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    Molecular diversity among South East Asian coconut (Cocos nucifera L.) germplasm accessions based on ISSR markers
    (2005-01) Manimekalai, R.; Nagarajan, P.; Bharathi, M.; Anitha Karun; Kumaran, P.M.; Parthasarathy, V.A.
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    Optimization of DNA Isolation and RAPD Technique in Arecanut (Areca catechu L.)
    (2007) Rajesh, M.K.; Bharathi, M.; Nagarajan, P.
    A simple and efficient protocol for extracting high quality DNA from arecanut (Areca catechu L.) leaves is presented. DNA yield and purity were monitored by gel electrophoresis and by determining absorbance at UV (A260/A280). The ratio was between 1.7 to 1.9 indicating that the presence of contaminating metabolites was minimal. The quantities of DNA obtained were 100- 400 ig/g starting material. The isolated DNA proved amenable to PCR amplification and restriction digestion. DNA was completely digested with the three restriction enzymes (EcoR I, EcoR V and Hind III) confirming the purity of the extracted DNA. Using the isolated DNA, the parameters for randomly amplified polymorphic DNA (RAPD) protocol was standardized.