Self-compatibility of 'Katy' apricot (Prunus armeniaca L.) is associated with pollen-part mutations.
Apricot (Prunus armeniaca L.) cultivars originated in China display a typical S-RNase-based gametophytic self-incompatibility (GSI). 'Katy', a natural self-compatible cultivar belonging to the European ecotype group, was used as a useful material for breeding new cultivars with high frequency of self-compatibility by hybridizing with Chinese native cultivars. In this work, the pollen-S genes (S-haplotype-specific F-box gene, or SFB gene) of 'Katy' were first identified as SFB₁ and SFB (8), and the S-genotype was determined as S₁ S₈. Genetic analysis of 'Katy' progenies under controlled pollination revealed that the stylar S₁-RNase and S₈-RNase have a normal function in rejecting wild-type pollen with the same S-haplotype, while the pollen grains carrying either the SFB₁ or the SFB₈ gene are both able to overcome the incompatibility barrier. However, the observed segregation ratios of the S-genotype did not fit the expected ratios under the assumption that the pollen-part mutations are linked to the S-locus. Moreover, alterations in the SFB₁ and SFB₈ genes and pollen-S duplications were not detected. These results indicated that the breakdown of SI in 'Katy' occurred in pollen, and other factors not linked to the S-locus, which caused a loss of pollen S-activity. These findings support a hypothesis that modifying factors other than the S-locus are required for GSI in apricot.
Wu
Jun
J
College of Horticulture, Nanjing Agricultural University, Nanjing, Jiangsu Province, People's Republic of China.
Gu
Chao
C
Du
Yu-Hu
YH
Wu
Hua-Qing
HQ
Liu
Wei-Sheng
WS
Liu
Ning
N
Lu
Juan
J
Zhang
Shao-Ling
SL
D009154:Mutation; D010940:Plant Proteins / Q000235:genetics; D011058:Pollen / Q000235:genetics* / Q000502:physiology; D027861:Prunus / Q000235:genetics* / Q000502:physiology*; D012260:Ribonucleases / Q000235:genetics; D057945:Self-Fertilization / Q000235:genetics / Q000502:physiology*
D010940:Plant Proteins; D012260:Ribonucleases; C022542:ribonuclease S