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Not AvailableAgrobiodiversity in drylands consisting of large number of field crops, horticultural crops, grasses, shrubs and multi-purpose trees plays a very critical role in providing food, fodder, nutritional and environmental security to the inhabitants of drylands. Despite several bio-physical constraints, the drylands support high human and livestock population with limited resources resulting in over-exploitation of the natural resources. moreover, drylands are more vulnerable to global warming-mediated climate changes such as intense drought, sudden rainfall burst, high ambient temperature and appearance of new unforeseen diseases and pests. In addition to other technological interventions, the management of agro-biodiversity in drylands is expected to be a key factor for sustainability, food and fodder security and for improving livelihood in drylands. Genetic resources of dryland species include local landraces, improved elite material, traditional cultivars, genetic stocks and wild relatives of coarse cereals (pearl millet, barley, sorghum, maize and small millets), legumes (chickpea, mungbean, mothbean, clusterbean), horticultural crops, grasses, shrubs, medicinal plants and multipurpose trees. A large numberof exotic and indigenous germplasm accessions are conserved in National Gene Bank or Field Gene Banks at the ICAR-National Bureau of Plant Genetic Resources (NPBGR) and elsewhere across globe. Characterization of genetic resources using prescribed descriptors has largely indicated existence of large variation for phenotypic, phenological, nutritional and stress-adaptation traits among available germplasm. research conducted so far has indicated that the genetic resources from drylands hold a unique advantage as they have evolved over centuries by natural and human selection under drought, high temperature or saline conditions. they are better adapted to the local conditions and would contribute in enhancing the resilience at the farm level. these resources could be of immense importance especially as sources of native genes conditioning resistance to various biotic and abiotic stresses and also make unique study material to understand the mechanism of adaptation to abiotic stresses. they could also serve as an excellent genomic resource for isolation of candidate genes for tolerance to climatic and edaphic stresses for accelerating further genetic improvement. However, only a very small fraction of these accessions has been utilized so far because of operational difficulties in dealing with large number of germplasm accessions. the development of core and mini-core in recent past is expected to improve this situation. Formation of trait-specific gene pools is also likely to enhance the utilization of genetic resources to a greater extent. there are multiple and complex challenges for agrobiodiversity in drylands due to habitat destruction, high grazing/browsing pressure, invasion of other species, unsustainable exploitation of natural resources and dilution of customary conservation practices. Critical assessment is needed for identifying geographical and trait-diversity gaps using GIS and other modern tools. additional explorations are needed in the regions where collection gaps have been indicated. Ex situconservation of genetic resources from such regions and distribution of germplasm to the stakeholders on regular basis would remain very crucial especially in the present scenario of climate change. Developing e-resources with detailed information like passport data, characterization and evaluation data with respect to individual accessions would certainly help in enhancing the utilization of genetic resources to broaden crop genetic base which is very essential to reduce the chances of disease epidemics and to adapt to the effects of climate change.Not Availabl

Molecular Characterization and Chromosomal Distribution of a Species-Specific Transcribed Centromeric Satellite Repeat from the Olive Fruit Fly, Bactrocera oleae

Satellite repetitive sequences that accumulate in the heterochromatin consist a large fraction of a genome and due to their properties are suggested to be implicated in centromere function. Current knowledge of heterochromatic regions of Bactrocera oleae genome, the major pest of the olive tree, is practically nonexistent. In our effort to explore the repetitive DNA portion of B. oleae genome, a novel satellite sequence designated BoR300 was isolated and cloned. The present study describes the genomic organization, abundance and chromosomal distribution of BoR300 which is organized in tandem, forming arrays of 298 bp-long monomers. Sequence analysis showed an AT content of 60.4%, a CENP-B like-motif and a high curvature value based on predictive models. Comparative analysis among randomly selected monomers demonstrated a high degree of sequence homogeneity (88% - 97%) of BoR300 repeats, which are present at approximately 3,000 copies per haploid genome accounting for about 0.28% of the total genomic DNA, based on two independent qPCR approaches. In addition, expression of the repeat was also confirmed through RT-PCR, by which BoR300 transcripts were detected in both sexes. Fluorescence in situ hybridization (FISH) of BoR300 on mitotic metaphases and polytene chromosomes revealed signals to the centromeres of two out of the six chromosomes which indicated a chromosome-specific centromeric localization. Moreover, BoR300 is not conserved in the closely related Bactrocera species tested and it is also absent in other dipterans, but it's rather restricted to the B. oleae genome. This feature of species-specificity attributed to BoR300 satellite makes it a good candidate as an identification probe of the insect among its relatives at early development stages