FAO/IAEA International Symposium on Plant Mutation Breeding and Biotechnology

GENETIC CHARACTERIZATION OF A NOVEL POLLEN-PART SELF-COMPATIBLE MUTANT OF JAPANESE PEAR IN PROGENY OF A CROSS USING POLLEN FROM A CHRONICALLY GAMMA-IRRADIATED TREE

Not scheduled

15m

IAEA, Vienna

Poster Mutation breeding for ornamental and vegetatively propagated crops

Speaker

Dr Nobuko Mase (Radiation Breeding Division, Institute of Crop Science, NARO)

Description

Most of the important fruit crops in the subtribe Pyrinae of the Rosaceae, such as apple and pear, exhibit S-RNase–based self-incompatibility. In 2013, we selected a pollen-part self-compatible mutant of Japanese pear (*Pyrus pyrifolia*), designated 415-1, from the progeny of a cross using pollen from a ‘Kosui’ tree chronically exposed to low-dose-rate gamma-irradiation in the gamma field at the Radiation Breeding Division, Institute of Crop Science, NARO. We developed a new self-compatible mutant selection (designated 391-1) of Japanese pear, which was identified from among male-derived progeny of a gamma-irradiated ‘Nijisseiki’ tree. CAPS analysis of the S-RNase genes indicated that the S haplotype of 391-1 was S2S4. Crosses between 391-1 and self-incompatible cultivars with S2 and/or S4 haplotypes revealed that the styles of 391-1 accepted S4 pollen but rejected S2 pollen. Furthermore, the pollen of 391-1 was not rejected by self-incompatible cultivars containing the same S haplotypes. Thus, this selection was determined to have mutations in both pollen and stylar functions of self-incompatibility. Segregation analyses of S haplotypes of the progeny of ‘Niitaka’ ×‌ 391-1 revealed a duplication of the S2 haplotype; thus, the accurate S haplotype of 391-1 is S2S2S4. Furthermore, segregation analyses of SSRs in the same linkage group as the S haplotype revealed a segmental duplication encompassing an S2 haplotype. Similarly, 415-1 (S4S5S5) has a segmental duplication encompassing an S5 haplotype. These results indicate that pollen-part self-compatibility in *Pyrus* does not require mutation of a pollen S factor, but can be caused by duplication of an S haplotype. Further, they demonstrate the effectiveness of using pollen from irradiated plants to obtain self-compatible mutants of fruit crops in the Pyrinae.