REFERENCE GENETIC LINKAGE MAPS OF EUROPEAN AND JAPANESE PEARS

Genetic linkage maps of the European pear (Pyrus communis L.) cultivars ‘Bartlett’ and ‘La France’ and the Japanese pear (P. pyrifolia Nakai) ‘Housui’ were constructed based on SSRs developed from pear and apple, AFLPs, and other markers.
The maps of ‘Bartlett’ and ‘Housui’ were constructed by using the F1 population from a cross between ‘Bartlett’ and ‘Housui’. A genetic linkage map of ‘Bartlett’ consisted of 504 loci including 92 pear SSRs, 77 apple SSRs, and 326 AFLPs, covering 17 linkage groups in a total length of 1,080 cM with an average distance of 2.1 cM between markers.
Another genetic linkage map of ‘Housui’ contained 356 loci including 68 pear SSRs, 52 apple SSRs, and 224 AFLPs, on 16 linkage groups encompassing a genetic distance of 1,180 cM. A genetic linkage map of ‘La France’ was constructed by using F1 individuals obtained from a cross between ‘Shinsei’ × ‘282-12’ (‘Housui’ × ‘La France’). The map consisted of 484 loci including 112 pear SSRs, 90 apple SSRs, and 279 AFLPs, on 17 linkage groups with a genetic distance of 1,204 cM. Thirty-five, 25, and 46 out of newly developed 98 SSR markers derived from pear ESTs were identified in the maps of ‘Bartlett’, ‘Housui’, and ‘La France’ respectively.
These three maps were well aligned using common SSR markers in all linkage groups (LGs) except for LG12. It is considered that the maps of ‘Bartlett’ and ‘La France’ cover almost all genome regions compared with the saturated apple reference map, whereas the map of ‘Housui’ lacks LG12 and covers very small regions of LG4 and LG5. Pear scab resistance genes (QTLs) of ‘La France’ against Venturia nashicola were positioned at LG2 and LG14 in a genetic linkage map of ‘La France’. In previous studies, a pear scab resistance gene of the Japanese pear ‘Kinchaku’ was identified in the middle of LG1 and a black spot response gene was found at the top of LG11. The self-incompatibility locus S was found at the bottom of LG17. Pear reference linkage maps combined with information on positions of interest genes will help to conduct marker-assisted selection and marker assisted breeding in pear breeding programs.

XII EUCARPIA Symposium on Fruit Breeding and Genetics

T. Yamamoto, S. Terakami, T. Kimura, Y. Sawamura, N. Takada, T. Hirabayashi, T. Imai, C. Nishitani

mapping, Pyrus pyrifolia, Pyrus communis, simple sequence repeats

https://doi.org/10.17660/ActaHortic.2009.814.101