ISOLATION AND CHARACTERIZATION OF GENES INVOLVED IN PEACH FRUIT QUALITY

¹ Institut National de la Recherche Agronomique (INRA), Station de Physiologie Végétale, BP81, 33 883 Villenave d'Ornon Cédex, FRANCE.

² Institut National de la Recherche Agronomique (INRA), Unité de Recherches sur les Espèces fruitières et la Vigne, BP81, 33 883 Villenave d'Ornon Cédex, FRANCE.

Sugar and organic acid contents and composition are important factors in determining peach (Prunus persica (L.) Batsch) fruit quality. We are interested in identifying genes underlying QTLs controlling these traits and already mapped using an F2 population from a cross between two peach cultivars with low acidity ('Jalousia') or normal acidity ('Fantasia'). A candidate gene approach has been undertaken. The aim is to detect co-locations between QTLs and genes, which may be functionally related to the traits. The first step towards this end is to isolate cDNAs expressed in peach fruit and corresponding to genes supposed to be involved in peach fruit acidity or non acidity. 20 cDNAs representing key proteins in (1) sugar loading in the fruit, (2) sugar and organic acid metabolism, (3) vacuolar storage of organic acids and (4) cell expansion were isolated using a RT-PCR strategy with degenerate primers, applied to 'Fantasia' fruits at 45 days after bloom. In parallel to their mapping, the expression patterns of these genes have been determined by Northern blot and RT-PCR throughout peach fruit development and in various organs (flower buds and young leaves) for 'Jalousia' and 'Fantasia'.