DNA AMPLIFIED FINGERPRINTING, A USEFUL TOOL FOR DETERMINATION OF GENETIC-ORIGIN AND DIVERSITY ANALYSIS IN CITRUS

We used three short repetitive nucleotide sequences [(GTG)5, (TCC)5, a nd (GACA)4] either as radiolabeled probes for hybridization with restr icted citrus DNA or as single primers in polymer ase chain reaction am plification experiments with total genomic DNA. We tested the ability of the sequences to discriminate between seedlings of zygotic or nucel lar origin in the progeny of a Volkamer lemon (Citrus volkameriana Ten . & Pasq.) tree. The genetic variability within two species [Citrus si nensis (L.) Osbeck (sweet oranges) and Citrus reticulata Blanco and re latives (mandarins)] also was evaluated. DNA amplified fingerprinting with single primers was,the more successful technique for discriminati ng between nucellar and zygotic seedlings. Although we were not able t o distinguish among 10 cultivars of C. sinensis, all 10 C. reticulata cultivars tested were distinguishable. However, it still is difficult to identify the putative parents of a hybrid plant when the two parent al genomes are closely related.