title: Self-incompatibility in Petunia inflata: the relationship between a self-incompatibility locus F-box protein and its non-self S-RNases.
abstract: The highly polymorphic S (for self-incompatibility) locus regulates self-incompatibility in Petunia inflata; the S-RNase regulates pistil specificity, and multiple S-locus F-box (SLF) genes regulate pollen specificity. The collaborative non-self recognition model predicts that, for any S-haplotype, an unknown number of SLFs collectively recognize all non-self S-RNases to mediate their ubiquitination and degradation. Using a gain-of-function assay, we examined the relationships between S2-SLF1 (for S2-allelic product of Type-1 SLF) and four S-RNases. The results suggest that S2-SLF1 interacts with S7- and S13-RNases, and the previously identified S1- and S3-RNases, but not with S5- or S11-RNase. An artificial microRNA expressed by the S2-SLF1 promoter, but not by the vegetative cell-specific promoter, Late Anther Tomato 52, suppressed expression of S2-SLF1 in S2 pollen, suggesting that SLF1 is specific to the generative cell. The S2 pollen with S2-SLF1 suppressed was compatible with S3-, S5-, S7-, S11-, and S13-carrying pistils, confirming that other SLF proteins are responsible for detoxifying S5- and S11-RNases and suggesting that S2-SLF1 is not the only SLF in S2 pollen that interacts with S3-, S7-, and S13-RNases. Petunia may have evolved at least two types of SLF proteins to detoxify any non-self S-RNase to minimize the deleterious effects of mutation in any SLF.
authors: Intercollege Graduate Degree Program in Plant Biology, Pensylvania State University, University Park, PA 16802, USA.
authors: Penglin
authors: P
authors: Sun
authors: Teh-hui
authors: TH
authors: Kao
mesh_terms: D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D056426:Genetic Loci; D018551:Solanum lycopersicum / Q000235:genetics; D035683:MicroRNAs; D008969:Molecular Sequence Data; D032306:Petunia / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics; D011401:Promoter Regions, Genetic; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D060436:Self-Incompatibility in Flowering Plants
chemical_list: D044783:F-Box Proteins; D035683:MicroRNAs; D010940:Plant Proteins; D012260:Ribonucleases; C022542:ribonuclease S; C110993:self-incompatibility ribonuclease S3