Establishment of cDNA Library and EST Analysis from Leaves of Phyllanthus amarus

Abstract

DNA sequencing of randomly chosen clones from a cDNA library allows thousands of different transcripts to be identified. However, since the likelihood of observing a given transcript is proportional to the expression level of that transcript in the tissue from which the library is derived, often transcripts are represented by several EST sequences. An expressed sequence tags (EST) analysis was undertaken to identify the genes present in the leaves of Phyllanthus amarus, which is a small tropical, glabrous herb with several health benefits. Phyllanthin and hypophyllanthin, major bioactive components, present in highest amounts in the leaves, are of significant therapeutic importance like hepatoprotective, antioxidant, antiviral, hypoglycemic, etc. Taken together, sequencing of cDNA clones generated high-quality ESTs (Accession number: JK492908 to JK492964) with high similarities with genes from Ricinus communis, Onchocerca volvulus, Eucalyptus globules, Gossypium hirsutum, Nicotiana tabacum, Solanum spp. and many more. A BLASTN analysis along with BLASTX analysis of all the unique sequences was performed and was grouped according to the reported activities. Results represented here is the first reference collection of ESTs from this commercially important medicinal herb. This study indicated that the leaf transcriptome contains series of interesting sequences like ALBINO3, ribulose-1, 5 bisphosphate carboxylase/ oxygenase (RUBISCO), chloroplast photosystem II chlorophyll A/B-binding protein, stress-responsive proteins like methionine sulfoxide reductase type, etc.