Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Oral Communication Abstract

CHARACTERIZATION AND GENOMIC LOCALIZATION OF RESISTANCE GENE HOMOLOGUES IN THE APPLE GENOME

GIANFRANCESCHI L.*, PATOCCHI A.**, DURANTE C.*, VINATZER B.***, TARTARINI S.***, KOMJANC M.****, GESSLER C.**, SANSAVINI S.***

* Dipartimento di Genetica e di Biologia dei Microrganismi, Università degli Studi di Milano

** Plant Pathology,Iinstitute of Plant Sciences, ETH, Zurich, Switzerland

*** Dipartimento di Colture Arboree, Università di Bologna

**** Istituto Agrario San Michele all’Adige, S. Michele all’Adige, Trento

Scab, caused by the fungal pathogen Venturia inaequalis, is the most common disease of the cultivated apple (Malus x domestica Borkh.). Monogenic resistance against scab is found in some small-fruited wild Malus species and has been used in apple breeding for scab resistance. Vf resistance of Malus floribunda 821 is the most widely used scab resistance source. Recently the identification and sequencing of a cluster of receptor-like genes with homology to the Cf Cladosprium fulvum resistance gene family of tomato, isolated from the Vf region, has been reported. During the screening of a BAC library we identified Cf homologues from other regions of the apple genome. The work we present here is the analysis of the genomic structure of those resistance gene homologues. We are currently isolating SSR markers from the BAC clones to be used as genetic markers to position the BACs onto the European apple genetic map (Malieepaard et al). The identification of polymorphic markers tightly linked to resistance gene homologues is a very powerful tool to establish whether those homologues play a role in controlling other disease resistances or if they are allelic to other known resistance genes introgressed from wild Malus species. Finally, sequence comparison between the newly identified genes and those isolated from the Vf region will allow the characterisation of the gene family, determining the level of similarity existing among the homologues, leading to a better understanding of the plant defence mechanism.