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

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 4.53

MAPPING OF AN ALLELE SPECIFIC MARKER FOR 1- AMINOCYCLOPROPANE-1- CARBOXYLATE OXIDASE MD-ACO1 IN APPLE

COSTA F.*, VAN DE WEG W.E.**, STELLA S.*, SANSAVINI S.*

*) Dipartimento di Colture Arboree, University of Bologna, Bologna, Italy

**) Plant Research International, Wageningen, Netherlands

ethylene, ACO markers, map, apple

Ethylene plays a fundamental role in regulating fruit ripening processes (Oetiker et al. 1995; Picton et al. 1995). Ethylene’s biosynthetic pathway is largely controlled by two enzymes, 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxydase (ACO), the latter also called ethylene forming enzyme (EFE) because it is involved in the final formation of ethylene (Picton et al. 1995). Recent studies conducted on tomato indicate that ethylene may also be actively involved during fruit flesh softening (Rose et al.,1997). In cultivated apple (Malus x domestica Borkh), data bank searches (http://www.ncbi.nlm.nih.gov/) have turned up several sequences for ACO, which were subsequently aligned. CLUSTALW (http://www.embl-heidelberg.de/) analysis made it possible to identify the highest homologous areas, on which primers were then designed. A pair of these primers, Md-ACO1pF and Md-ACO1R amplified a polymorphic marker Md-ACO1 in a panel of 18 apple varieties. A crossing population derived from the cvs. Mondial Gala and Fuji is under examination at the University of Bologna for, fruit quality, especially focussing on the relation between ethylene release and flesh firmness. Note, too, that there is a molecular map of apple (Prima x Fiesta) saturated with markers of the Vf gene for scab resistance. The parental cultivars are polymorphic for the MdACO1 marker, and the related gene could be mapped on linkage group 10 of a molecular linkage map. Md-ACO1 also segregates in the cross Prima x Fiesta, where it also mapped on linkage group 10 in the QTL region for firmness identified by King et al. (2000) and Maliepaard et al. (2001). The Md-ACO1 bands amplified in both Mondial Gala and Fuji were subsequently cloned and sequenced to corroborate the fact that the genome fragment found with the primer pair Md-ACOpF and Md-ACOR actually belonged to the ACO gene family. The Homology Search-FASTA (http://www.ddbj.nig.ac.jp/) registered a very high homology (95.67%-97.28% range) with a gene coding for ACC-oxidase in Malus domestica .

King GJ, Maliepaard C, Lynn JR, Alston FH, Durel CE, Evans KM, Griffon B, Laurens F, Manganaris AG, Schrevens E, Tartarini S (2000) Quantitative genetic analysis and comparison of physical and sensory descriptors relating to fruit flesh firmness in apple (Malus pumila Mill.). TAG 100: 1074-1084

Maliepaard C., MJ Silanpää, JW van Ooijen, RC Jansen, E Arjas (2001). Bayesian versus frequentitst analysis of multiple quantitative trait loci with an application to an outbred apple cross. TAG 103: 1243-1253.