Pollen S–locus F–box proteins of Petunia involved in S–RNase‐based self‐incompatibility are themselves subject to ubiquitin‐mediated degradation. (31st May 2015)

• Record Type: Journal Article
• Authors: Sun, Penglin; Li, Shu; Lu, Dihong; Williams, Justin S.; Kao, Teh‐Hui
• Is Part Of: Plant journal. Volume 83:Number 2(2015:Jul.)
• Page Start: 213
• Page End: 223
• Publication Date: 2015-05-31
• Subjects: Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.12880
• Languages: English
• ISSNs: 0960-7412

Abstract

<abstract abstract-type="main" id="tpj12880-abs-0001"> <title>Summary</title> <p>Many flowering plants show self‐incompatibility, an intra‐specific reproductive barrier by which pistils reject self‐pollen to prevent inbreeding and accept non‐self pollen to promote out‐crossing. In <italic>Petunia</italic>, the polymorphic S–locus determines self/non‐self recognition. The locus contains a gene encoding an S–RNase, which controls pistil specificity, and multiple <italic>S‐locus F‐box</italic> (<italic>SLF</italic>) genes that collectively control pollen specificity. Each SLF is a component of an SCF (Skp1/Cullin/F‐box) complex that is responsible for mediating degradation of non‐self S‐RNase(s), with which the SLF interacts, via the ubiquitin–26S proteasome pathway. A complete set of SLFs is required to detoxify all non‐self S‐RNases to allow cross‐compatible pollination. Here, we show that SLF1 of <italic>Petunia inflata</italic> is itself subject to degradation via the ubiquitin–26S proteasome pathway, and identify an 18 amino acid sequence in the C‐terminal region of S<sub>2</sub>‐SLF1 (SLF1 of <italic>S</italic><sub><italic>2</italic></sub> haplotype) that contains a degradation motif. Seven of the 18 amino acids are conserved among all 17 SLF proteins of <italic>S</italic><sub><italic>2</italic></sub> haplotype and <italic>S</italic><sub><italic>3</italic></sub> haplotype involved in pollen specificity, suggesting that all SLF proteins are probably subject to similar degradation. Deleting the 18 amino acid sequence from S<sub>2</sub>‐SLF1 stabilized the protein but abolished its function in self‐incompatibility, suggesting that dynamic cycling of SLF proteins is an integral part of their function in self‐incompatibility.</p> </abstract>