Sequence analysis of the Petunia inflata S‐locus region containing 17 S‐Locus F‐Box genes and the S‐RNase gene involved in self‐incompatibility. (30th October 2020)

• Record Type: Journal Article
• Authors: Wu, Lihua; Williams, Justin S.; Sun, Linhan; Kao, Teh‐Hui
• Is Part Of: Plant journal. Volume 104:Number 5(2020)
• Page Start: 1348
• Page End: 1368
• Publication Date: 2020-10-30
• Subjects: S‐locus -- self‐incompatibility -- S‐locus F‐box genes -- S‐RNase -- S‐locus F‐box pseudogenes -- Petunia -- genetic exchange -- retrotransposition -- Solanaceae; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.15005
• Languages: English
• ISSNs: 0960-7412

Abstract

SUMMARY: Self‐incompatibility in Petunia is controlled by the polymorphic S ‐locus, which contains S‐RNase encoding the pistil determinant and 16–20 S‐locus F‐box ( SLF ) genes collectively encoding the pollen determinant. Here we sequenced and assembled approximately 3.1 Mb of the S2 ‐haplotype of the S ‐locus in Petunia inflata using bacterial artificial chromosome clones collectively containing all 17 SLF genes, SLFLike1, and S‐RNase . Two SLF pseudogenes and 28 potential protein‐coding genes were identified, 20 of which were also found at the S ‐loci of both the S6a ‐haplotype of P. inflata and the SN ‐haplotype of self‐compatible Petunia axillaris, but not in the S ‐locus remnants of self‐compatible potato ( Solanum tuberosum ) and tomato ( Solanum lycopersicum ). Comparative analyses of S ‐locus sequences of these three S ‐haplotypes revealed potential genetic exchange in the flanking regions of SLF genes, resulting in highly similar flanking regions between different types of SLF and between alleles of the same type of SLF of different S ‐haplotypes. The high degree of sequence similarity in the flanking regions could often be explained by the presence of similar long terminal repeat retroelements, which were enriched at the S ‐loci of all three S ‐haplotypes and in the flanking regions of all S ‐locus genes examined. We also found evidence of the association of transposable elements with SLF pseudogenes. Based on the hypothesis that SLF genes were derived by retrotransposition, we identified 10 F‐box genes as putative SLF parent genes. Our results shed light on the importance of non‐coding sequences in the evolution of the S ‐locus, and on possible evolutionary mechanisms of generation, proliferation, and deletion of SLF genes. Significance Statement: Sequencing the Petunia S ‐locus region of the S2 ‐haplotype containing 17 S‐locus F‐box ( SLF ) genes, SLFLike1, and the S‐RNase gene allows comparative analyses of the approximately 3.1 Mb assembled sequence with the S ‐locus sequences of other S ‐haplotypes of Petunia and S ‐locus remnants of several self‐compatible solanaceous species. The results from comparison in both the coding and non‐coding flanking sequences of SLF genes shed light on the genomic organization and evolution of the S ‐locus in Petunia .