Articles written in Journal of Genetics

    • Expression patterns of anArabidopsis phenylalanine ammonia-lyase promoter in transgenic tobacco

      S. V. Naga Prasad M. Thungapathra Vindhya Mohindra Kailash C. Upadhyaya

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      We have cloned and characterized one of the genes that encode phenylalanine ammonia-lyase fromArabidopsis thaliana. A 1.8-kb fragment containing the upstream region of this gene,PALI, was transcriptionally fused to the ß-glucuronidase reporter gene, and the construct was introduced into tobacco byAgrobacterium-mediated leaf disc transformation. The distribution of ß-glucuronidase activity in the transgenic plants was analysed histochemically. The spatial pattern of activity showed that thePALI promoter is very active in the vascular tissues. No expression was observed in epidermal cells, trichomes and apical meristems. Activation of thePALI promoter in the early stages of seedling development remained confined to the regions adjacent to the root apical meristems; in later stages of seedling development, the pattern of expression was drastically altered. The results suggest that thePALI promoter is under the control of a complex set of signal transduction pathways which lead to its activation in response to tissue-specific, wounding and developmental cues.

    • Analysis of genetic diversity in pigeon pea germplasm using retrotransposon-based molecular markers


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      Pigeon pea (Cajanus cajan), an important legume crop is predominantly cultivated in tropical and subtropical regions of Asia and Africa. It is normally considered to have a low degree of genetic diversity, an impediment in undertaking crop improvement programmes.We have analysed genetic polymorphism of domesticated pigeon pea germplasm (47 accessions) across the world using earlier characterized panzee retrotransposon-based molecularmarkers. Itwas conjectured that since retrotransposons are interspersed throughout the genome, retroelements-based markers would be able to uncover polymorphism possibly inherent in the diversity of retroelement sequences. Two PCR-based techniques, sequence-specific amplified polymorphism (SSAP) and retrotransposon microsatellite amplified polymorphism (REMAP) were utilized for the analyses.We show that a considerable degree of polymorphism could be detected using these techniques. Three primer combinations in SSAP generated 297 amplified products across 47 accessionswith an average of 99 amplicons per assay. Degree of polymorphism varied from 84–95%. In the REMAP assays, the number of amplicons was much less but up to 73% polymorphism could be detected. On the basis of similarity coefficients, dendrograms were constructed. The results demonstrate that the retrotransposon-based markers could serve as a better alternative for the assessment of genetic diversity in crops with apparent low genetic base.

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