Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Genomic libraries of AM fungi

Arbuscular mycorrhizal (AM) fungi cannot be grown alone in pure culture, which limits the source of available genomic DNA. Spores of AM fungi (produced in association with a host plant) house hundreds to thousands of nuclei, each of which generally contains 0.1 to 1pg DNA depending on the fungal species.

Genomic libraries were constructed from DNA, which was extracted from a large number of spores of G. mosseae (50000), Gig. margarita (18000) and Gig. rosea (18000), isolated from pure pot cultures.

Extracted DNA was purified on a CsCl gradient, restricted with BamHI or BglII, and ligated into a lambda-ZAPII or lambda-DASHII cloning vectors. l-ZAPII libraries (average insert size 1 to 4 kb) were obtained for all three fungi using BamHI, and absence of procaryotic DNA was confirmed in the libraries. The lambda-ZAPII libraries represent between 2 and 2.5 fold the fungal genome and they have proved useful for isolating repetitive DNA elements from each of the three fungi.

Two genomic libraries of G. mosseae were constructed in the lambda-DASH-II vector without CsCl centrifugation of the sporal DNA (to limit DNA shearing) and after restriction with BamHI or BglII. Large subunit ribosomal DNA (25S rDNA) and several published protein encoding genes of known or unknown function were identified in the genomic library constructed from DNA restricted with BglII, and which is estimated to represent at least 6 times the fungal genome. This genomic library may be useful for the isolation of low copy genes.

More information on the Genomyca -project can be found at: http://www.dijon.inra.fr/genomyca/

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Reported by

Institut national de la recherche agronomique
UMR 1088 PME, INRA-CMSE
21065 Dijon
France
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