Physical mapping of three fruit ripening genes: En-dopolygalacturonase, ACC oxidase and ACC synthase from apple (Malus x domestica) in an apple rootstock A106 (Malus sieboldii)

摘要

The apple rootstock, A106 (Malus sieboldii), had 17 bivalents in pollen mother cells at meiotic metaphase 1, and 17 chromosomes in a haploid pollen cell. Karyotypes were prepared from root-tip cells with 2n = 34 chromosomes. Seven out of 82 karyotypes (8.5%) showed one pair of satellites at the end of the short arm of chromosome 3. C-bands were shown on 6 pairs of chromosomes 2, 4, 6, 8, 14, and 16 near the telomeric regions of short arms. Probes for three ripening-related genes from Malus x do-mestica: endopolygalacturonase (EPG, 0.6 kb), ACC oxidase (1.2 kb), and ACC synthase (2 kb) were hybridized in situ to metaphase chromosomes of A106. Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11. For the ACC oxidase gene, hybridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively, proximal to the centromere of chromosome 1 in 81% of the spreads, and on the long arm of chromosome 13 in 50% of the spreads. Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telom-eric region of the short arm of chromosome 12 in 96% of the spreads, chromosomes 9 and 10 in 76% of the spreads, and chromosome 17 in 56% of the spreads.