Browsing by Author "Shailendra Sharma"

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Assessment of genetic diversity in common bean (Phaseolus vulgaris L.) germplasm using amplified fragment length polymorphism (AFLP)
(2008) Vipin Kumar; Shailendra Sharma; Shubham Kero; Shiveta Sharma; Amit K. Sharma; Mukesh Kumar; K. Venkataramana Bhat
AFLP technique was applied to assess genetic diversity among 44 common bean accessions that included 6 exotic accessions, 15 Indian land races and 23 released varieties. Eight AFLP primer pairs were used that produced 820 products of which 698 were polymorphic (85.12%). Wide variations were observed among all the accessions for the number of amplification products, percent polymorphism and average polymorphism information content (PIC). The Jaccard's similarity indices (J) based on the AFLP profiles were subjected to UPGMA cluster analysis. The dendrogram generated revealed seven major groups. Seventeen out of 23 released varieties were restricted to clusters VI and VII. The value of r = 0.934 in Mantel's test for cophenetic corrlelation applied to the cluster analysis indicated the high fitness of the accessions to a group. The germplasm used in the present study had narrow genetic base, although moderate to high genetic diversity was observed. The details of diversity analysis and the potential use of Indian common bean accessions in common bean breeding programme are provided in the present study. © 2008 Elsevier B.V. All rights reserved.
Colonization behavior of bacterium Burkholderia cepacia inside the Oryza sativa roots visualized using green fluorescent protein reporter
(2008) Shiveta Sharma; Shailendra Sharma; Ramesh K. Singh; Akhauri Vaishampayan
Colonization behavior of endophytic bacteria Burkholderia cepacia strains RRE-3 and RRE-5 was studied in the seedlings of rice variety NDR97 using confocal laser scanning microscopy under controlled laboratory and greenhouse conditions. For studying colonization pattern, bacterial strains were tagged with pHRGFPGUS plasmid. The role of bacterial strains (both gfp/gus-tagged and untagged) in growth promotion was also studied. After coming into contact with the host root system the bacteria showed an irregular spreading. Dense colonization was observed on the primary and secondary roots and also on the junction of emergence of the lateral roots. Results showed that the colonization pattern of Burkholderia cepacia strains was similar to that of other endophytic bacteria isolated from non-legumes. Burkholderia cepacia got entry inside the root at the sites of emergence of lateral roots, without formation of infection threads as in the case of symbiotic rhizobacteria. Observations suggested that the endophytic bacterial strains RRE-3 and RRE-5 entered inside the rice roots in a progressive manner. Bacteria were found to line up along the intercellular spaces of adjoining epidermal cells adjacent to the lateral root junction, indicating endophytic colonization pattern of Burkholderia cepacia strains. Experiments with the rice seedlings inoculated with RRE-3 and RRE-5 strains revealed that both strains enhanced plant growth considerably when observed under laboratory and greenhouse conditions and produced significantly higher plant biomass. No considerable difference was observed between the gfp/gus-tagged and non-gfp/gus-tagged strains in the plant growth experiments both in the laboratory and greenhouse conditions. © 2007 Springer Science+Business Media B.V.
Comparative analysis of diversity based on morpho-agronomic traits and microsatellite markers in common bean
(2009) Vipin Kumar; Shailendra Sharma; Amit Kumar Sharma; Shiveta Sharma; K. Venkataramana Bhat
Morpho-agronomic traits and microsatellite markers were used to survey genetic diversity in 115 common bean genotypes that included 70 Indian landraces, 24 released varieties and 21 exotic accessions. Twelve morpho-agronomic traits, namely, days to 50% flowering, leaflet length, leaflet width, pod length, pod width, number of pods per plant, days to maturity, seed length, seed width, number of seeds per pod, 100 seed weight and seed yield per plant were studied. Field data of two consecutive years were subjected to multivariate analysis as proposed by Mahalanobis's D2-statistics, Tochers method of clustering and combined analysis of variance. Seventeen microsatellite markers were also used to examine genetic diversity at molecular level that showed polymorphic information content (PIC) in the range of 0.00-0.684. Dendrograms based on Euclidean distances and UPGMA analysis showed the presence of majority of released varieties into single cluster, which pointed toward their low genetic base in comparison to indigenous landraces and exotic germplasm. Significant correlation existed between morphological genetic distance and microsatellite genetic distance tested by Mantel test (r = 0.876). © Springer Science+Business Media B.V. 2009.
Genetic diversity in Indian common bean (Phaseolus vulgaris L.) using random amplified polymorphic DNA markers
(2008) Vipin Kumar; Shailendra Sharma; Amit Kumar Sharma; Mukesh Kumar; Shiveta Sharma; Sunil Malik; K.P. Singh; R.S. Sanger; K.V. Bhat
Genetic diversity of twenty-six common bean (Phaseolus vulgaris L.) accessions of diverse geographical origin was studied using Random Amplified Polymorphic DNA (RAPD) markers. Fifteen out of forty four primers screened showed polymorphism across present set of genotypes. A total of 124 amplicons were scored using these 15 primers. Ninety five percent of the amplified products showed polymorphism, indicating fair amount of variation at the DNA level among these accessions. Cluster analysis delineated the genotypes in to four groups. © 2008 Prof. H.S. Srivastava Foundation for Science and Society.