BREEDING AND CHARACTERISTICS OF SYMMETRIC INTERGENERIC HYBRIDS BETWEEN APPLE AND PEAR

Cross-pollinated embryos of ‘Fuji’ apple x ‘Oharabeni’ pear were cultured in the half-strength of MS medium supplemented with 0.5 mg/L BA, 0.1 mg/L IBA, and 70 g/L coconut water in order to introduce new characteristics from pear to apple such as resistance to apple blotch and apple scab.
Leaf and shoot morphology of hybrids generally resembled ‘Oharabeni’. The graft-compatibility of these hybrids on five kinds of apple and pear rootstocks was the highest on ‘Old Home’ pear.
All of the five hybrids tested showed resistance to apple blotch, apple scab, pear scab, and pear rust.
Analyses of S-gene, SSRs, isozyme, RAPD marker and chromosome number suggested that all of the progenies were symmetric intergeneric hybrids receiving both genome equally.
Two linkage maps of ‘Fuji’ and ‘Oharabeni’ were constructed separately from the segregation data of these genotypes and DNA markers in the 17 progenies using a MAPL 98 mapping software.
The linkage map of ‘Fuji’ consisted of 17 linkage groups spanning 899.1 cM, in which each locus of isozyme, S-gene and SSRs was mapped.
The linkage map of ‘Oharabeni’ consisted of 23 linkage groups spanning 1328.8 cM, in which each locus of isozyme, S-gene, SSRs and the phenotype of red leaf was mapped.
These results offer a new breeding strategy for multiple-disease resistance and a novel strategy for the simultaneous genetic mapping and its integration in apple and pear using their intergeneric hybrids.