BIOCHEMICAL AND MOLECULAR CHARACTERIZATION OF ISABGOL
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Date
2002
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AAU, Anand
Abstract
Plantago ovata Forsk, commonly known as "Isabgol" belongs to the family Plantaginaceae. It is a native of Mediterranean region and is cultivated for its valuable husk. Although, it has various medicinal uses but less exploited for research at biochemical and molecular level. India is the sole country in the world, which commonly cultivates the Isabgol and is the largest exporter for the same. In addition to husk, Isabgol contains sufficient amount of essential amino acids (Lysine and Methionine), which are deficit in cereals and pulses. The seeds of Isabgol can be used as supplement to cereals and pulses. The study showed that the highest amount of oil, husk, total carbohydrates, cellulose and protein are present in the genotypes DM3 (4.06%), EC124345 & JI65 (36%), EC124345 & J165 (63%), EC124345 (7.7%) and DM3 (18%), respectively and present in very low amounts in the genotypes JI10 (3.25%), DM3 (31%), DM3 & DM1 (51%)), DM1 (4.2%) and EC124345&JI65(15%). It was also observed that the activity of peroxidase is more in genotype EC 124345, which is found to be resistant to downy mildew. On the other hand, the activity of polyphenol oxidase is more in the genotype DM3, which is found to be susceptible to downy mildew. Phenotypic variations are very less in Isabgol and the genotypes are mostly classified on the basis of Disease Index, because in Isabgol downy mildew disease is very severe and causes high yield loss. The markers include biochemical constituents (eg secondary metabolites in plants) and macromolecules, viz. proteins and DNA. Analysis of secondary metabolites is, however, restricted to those plants that produce a suitable range of metabolites, which can be easily analyzed and distinguished between cultivars. The metabolites, which are being used as markers, should be ideally neutral to environmental effects or management practices. Hence, amongst the molecular markers used, DNA markers are more suitable and ubiquitous to most living organisms. Genetic maps comprising closely spaced DNA markers are useful for genome analysis. Molecular markers have several advantages over the traditional phenotypic markers that were previously available to plant breeders. These markers are not environmentally regulated and are, therefore, unaffected by the conditions in which the plants are grown and are detectable in all stages of growth. RAPD, CAPS, ISSR and AFLP markers were used in fingerprinting and to examine genetic diversity among twelve genotypes of the Plantago ovata Forsk. RAPD and ISSR generated unique profiles for each genotype. CAPS could not distinguish between three of the genotypes DM1, JI10 and GI2, whereas, AFLP could not distinguish between DM1 and JI10. Similarity matrices and dendrograms illustrated the genetic similarities between the different genotypes except some clustering variations, which depend upon the type of marker used. Similarity and variation among the Isabgol genotypes were observed by cluster analysis and dendrograms were constructed, which were compared with the dendrogram from biochemical characters and finally the clustering was done using the plant/per cent disease index (PDI), which formed cluster between the genotypes originated at the same place eg JI10, JI42, JI53 and JI56 (developed at Jagudan) except JI65 which showed the similarities with the genotypes developed at Anand (DM1, DM2, DM3 and DM4).
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BIOCHEMISTRY, A STUDY