Isozyme analysis revealed that the Portuguese mandarin Carvalhais originated as a single clone

'Carvalhais' mandarin is a well-known Portuguese mandarin used in several Citrus breeding programmes throughout the world. The first step in the implementation of a breeding programme of this variety was to screen for its natural genetic variability. A significant number of adult trees and young seedlings were submitted to isozyme analysis. For better interpretation of the isozyme patterns of 'Carvalhais', several plants resulting from crosses between this Portuguese mandarin cultivar and the monoembryonic mandarin cultivar Clementine MA3 SRA 649, were also analysed. All the analysed trees of 'Carvalhais' showed similar monomorphic patterns for each isozyme system, indicating that this mandarin cultivar originated as a single initial clone. Young seedlings exhibited monomorphic isozyme patterns identical to the adult plants revealing a high level of apomixis in this cultivar. (Résumé d'auteur