Abstract
The primary goal of this study was to identify, clone and analyse new S-gene sequences in order to provide a basis for identifying amino acid residues that confer S-allele specificity. Three new putative S-alleles from Papaver rhoeas and Papaver nudicaule were identified using immunological and PCR methods. cDNAs encoding full-length open reading frames of the P. rhoeas S 8 and P. nudicaule Sn 1 genes were isolated. Nucleotide sequencing of these cDNAs, together with the partial S 7 sequence obtained by PCR, was used to derive the corresponding amino acid sequences. It is of interest that the P. nudicaule Sn1 sequence, which is the first S-allele isolated from another species of Papaver, shares a closer sequence identity to the P. rhoeas S3 amino acid sequence than S3 does to S1 from P. rhoeas. The identity of the S8 allele was confirmed by expressing the coding region in Escherichia coli and demonstrating that the recombinant protein, designated S8e, specifically inhibited S 8 pollen in an in vitro bioassay.
Information from sequence analysis of the S8, Sn1 and partial S7 amino acid sequences revealed important information about Papaver S-proteins. It confirmed previous observations based on only two S-alleles, that whilst exhibiting a high degree of amino acid sequence polymorphism ranging from 51.3% to 63.7%, these molecules probably share very similar secondary structures. These studies also revealed that, in contrast to the S-proteins from the Solanaceae and Brassica, amino acid sequence variation is not found in hypervariable blocks, but instead, is found throughout the S-proteins, interspersed with numerous short strictly conserved segments.
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Received: 16 March 1998 / Revision accepted: 19 May 1998
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Kurup, S., Ride, J., Jordan, N. et al. Identification and cloning of related self-incompatibility S-genes in Papaver rhoeas and Papaver nudicaule . Sex Plant Reprod 11, 192–198 (1998). https://doi.org/10.1007/s004970050141
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DOI: https://doi.org/10.1007/s004970050141