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

'Carvalhais' mandarin is a well-known Portuguese mandarin used in several C itrus breeding programmes throughout the world. The first step in the imple mentation of a breeding programme of this variety was to screen for its nat ural genetic variability. A significant number of adult trees and young see dlings were submitted to isozyme analysis. For better interpretation of the isozyme patterns of 'Carvalhais', several plants resulting from crosses be tween this Portuguese mandarin cultivar and the monoembryonic mandarin cult ivar Clementine MA3 SRA 649, were also analysed. All the analysed trees of 'Carvalhais' showed similar monomorphic patterns for each isozyme system, i ndicating that this mandarin cultivar originated as a single initial clone. Young seedlings exhibited monomorphic isozyme patterns identical to the ad ult plants revealing a high level of apomixis in this cultivar. (C) 1999 El sevier Science B.V. All rights reserved.