S haplotype-specific F-box protein gene, SFB, is defective in self-compatible haplotypes of Prunus avium and P. mume

• Published in: The Plant journal : for cell and molecular biology 2004-08, Vol.39 (4), p.573-586
• Main Authors: Ushijima, K, Yamane, H, Watari, A, Kakehi, E, Ikeda, K, Hauck, N.R, Iezzoni, A.F, Tao, R
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; apricots; Base Sequence; biochemical pathways; Biological and medical sciences; cherries; F-box protein; F-Box Proteins - genetics; fruit crops; fruit trees; Fundamental and applied biological sciences. Psychology; Haplotypes; Models, Biological; Molecular Sequence Data; nucleotide sequences; Phylogeny; Physical Chromosome Mapping; plant fertility; Plant physiology and development; plant proteins; Plant Proteins - chemistry; Plant Proteins - genetics; Pollen; pollen S gene; pollen‐part mutant; Prunus - classification; Prunus - genetics; Prunus avium; Prunus mume; ribonucleases; selfing; self‐incompatibility; Sequence Homology, Amino Acid; Sexual reproduction; SFB; S‐RNase; Vegetative and sexual reproduction, floral biology, fructification
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2004.02154.x

Many Prunus species, including sweet cherry and Japanese apricot, of the Rosaceae, display an S-RNase-based gametophytic self-incompatibility (GSI). The specificity of this outcrossing mechanism is determined by a minimum of two genes that are located in a multigene complex, termed the S locus, which controls the pistil and pollen specificities. SFB, a gene located in the S locus region, encodes an F-box protein that has appropriate S haplotype-specific variation to be the pollen determinant in the self-incompatibility reaction. This study characterizes SFBs of two self-compatible (SC) haplotypes, S4' and Sf, of Prunus. S4' of sweet cherry is a pollen-part mutant (PPM) that was produced by X-ray irradiation, while Sf of Japanese apricot is a naturally occurring SC haplotype that is considered to be a PPM. DNA sequence analysis revealed defects in both SFB4' and SFBf. A 4 bp deletion upstream from the HVa coding region of SFB4' causes a frame-shift that produces transcripts of a defective SFB lacking the two hypervariable regions, HVa and HVb. Similarly, the presence of a 6.8 kbp insertion in the middle of the SFBf coding region leads to transcripts for a defective SFB lacking the C-terminal half that contains HVa and HVb. As all reported SFBs of functional S haplotypes encode intact SFB, the fact that the partial loss-of-function mutations in SFB are present in SC mutant haplotypes of Prunus provides additional evidence that SFB is the pollen S gene in GSI in Prunus.