Self‐compatibility in Brassica napus is caused by independent mutations in S‐locus genes

Abstract

SummaryBrassica napus is an amphidiploid species with the A genome from Brassica rapa and the C genome from Brassica oleracea. Although B. rapa, B. oleracea and artificially synthesized amphidiploids with the AC genome are self-incompatible, B. napus is self-compatible. Six S genotypes were identified in B. napus, five of which had class I S haplotypes from one species and a class II S haplotype from the other species, and mutations causing self-compatibility were identified in three of these S genotypes. The most predominant S genotype (BnS-1;BnS-6), which is that of cv. 'Westar', had a class I S haplotype similar to B. rapa S-47 (BrS-47) and a class II S haplotype similar to B. oleracea S-15 (BoS-15). The stigmas of 'Westar' rejected the pollen grains of both BrS-47 and BoS-15, while reciprocal crossings were compatible. Insertion of a DNA fragment of about 3.6 kb was found in the promoter region of the SP11/SCR allele of BnS-1, and transcripts of SP11/SCR were not detected in 'Westar'. The nucleotide sequence of the SP11 genomic DNA of BnS-6 was 100% identical to that of SP11 of BoS-15. Class I SP11 alleles from one species showed dominance over class II SP11 alleles from the other species in artificially synthesized B. napus lines, suggesting that the non-functional dominant SP11 allele suppressed the expression of the recessive SP11 allele in 'Westar'. Two other S genotypes in B. napus also had non-functional class I S haplotypes together with recessive BnS-6. These observations suggest independent origins of self-compatibility in B. napus.

Phylogeny of <i>PolA1</i> Gene Consistent with the Relationships of U’s Triangle in <i>Brassica</i>

“…Two accessions (J113, J473) of B. juncea (AB genome) showed two PCR products, Rapa-S (183 bp) and Nig3 (112 bp), whereas two accessions (N117, N127) of B. napus (AC genome) had two PCR products, Rapa-L (242 bp) and Ole (221 bp), and two other accessions (N131, N135) showed two PCR products, Rapa-S (183 bp) and Ole (221 bp). This result indicates that B. napus has diphyletic origins, which was also suggested by an analysis of the S-locus gene (Okamoto et al, 2007).…”

Different status of the gene for ribosomal protein S16 in the chloroplast genome during evolution of the genus Arabidopsis and closely related species

“…Conversely, plants with a probably intact rps16 in their chloroplast genomes are selfincompatible (outcrossed) (Arabidopsis arenosa (Chen, 2007), Arabidopsis lyrata, and B. oleracea (Hall et al, 2002), and S. alba (Ford and Kay, 1985;Melzer et al, 1990)). The expressed sequence tags (ESTs) encoding the spliced rps16 genes of the chloroplast genomes of Raphanus raphanistrum (a self-incompatible plant; GenBank accession numbers: EY915189 and EY911083; (Sampson, 1967) and Brassica napus (self-compatible plant; GenBank accession number: EV076332; (Okamoto et al, 2007)) are available in the NCBI EST database. B. napus, Barbarea verna (http: //www.pfaf.org/user /Plant.aspx?LatinName= Barbarea verna), C. bursa-pastoris (Hintz et al, 2006), C. lasiocarpa (Tague, 2001), C. wallichii (Hall et al, 2002), L. virginicum (Lemen, 1980), and N. officinale (Manton, 1935) are selfcompatible, and self-compatible plants tend to lose the rps16 from their chloroplast genomes, whereas selfincompatible plants tend to retain the rps16 in their chlo-roplast genomes (Fig.…”

Self-incompatibility in passion fruit: cellular responses in incompatible pollinations

“…Another factor observed was that, the passion fruit sequence has an S-domain, identified in two different protein determinants of SSI, SRK and SLG (Okamoto et al 2007), suggesting that the passion fruit protein belongs to the S-domain family. These data can be explained by the fact that the receptor domain of the SRK protein is highly similar to SLG (Fujimoto et al 2006).…”