High-resolution mapping of theSandZloci ofPhalaris coerulescens

Abstract

Self incompatibility (SI) in Phalaris coerulescens is gametophytically determined by two unlinked multi allelic loci (S and Z). Neither the S nor Z genes have yet been cloned. As part of a map-based cloning strategy, high-resolution maps of the S and Z regions were generated from distorted segregating populations using RFLP probes from wheat, barley, oat, and Phalaris. The S locus was delimited to 0.26 cM with two boundary markers (Xwg811 and Xpsr168) and cosegregated with Xbm2 and Xbcd762. Xbcd266 was the closest marker linked to Z (0.9 cM). A high level of colinearity in the S and Z regions was found in both self-incompatible and -compatible species. The S locus was localized to the subcentromere region of chromosome 1 and the Z locus to the long arm end of chromosome 2. Several rice BAC clones orthologous to the S and Z locus regions were identified. This opens the possibility of using the rice genome sequence data to generate more closely linked markers and identify SI candidate genes. These results add further support to the conservation of gene order in the S and Z regions of the grass genomes.

Four QTLs determine crown rust (Puccinia coronata f. sp. lolii) resistance in a perennial ryegrass (Lolium perenne) population

“…This phenomenon of distorted segregation ratios of molecular markers due to self-incompatibility has been reported in other species including Fragaria (Sargent et al, 2004), citrus (Ruiz and Asins, 2003), and Phalaris coerulescens (Bian et al, 2004). However, on LG1, just three out of the eight distorted loci mapped close to CDO89 and OSE, markers known to map in the proximity of S (http:/ /ukcrop.net/perl/ace/search/ FoggDB).…”

Molecular and genetic characterization of the S locus in Hordeum bulbosum L., a wild self-incompatible species related to cultivated barley

“…The two parental individuals were selected based on a careful examination of seed set after self-and cross-pollinations (see Supplementary Table S2). Using the SMP1 or ZMP1 populations, we could detect recombinants between the S or Z loci and closely linked markers (M) without the necessity of genotyping for each locus, as was described by Leach (1988) and Bian et al (2004). A scheme for detecting recombinants using SMP1 is shown in Supplementary Fig.…”

“…HTL, a cDNA clone obtained from an anther cDNA library of H. bulbosum, was highly homologous with Bm2, which showed complete linkage to the S locus in Phalaris coerulescens (Bian et al 2004). bcd266, a cDNAderived RFLP marker from barley, was reported to be tightly linked to the Z locus in rye (Voylokov et al 1997;Hackauf and Wehling 2005) and P. coerulescens (Bian et al 2004).…”

“…High resolution maps of the S and Z regions were also generated in Phalaris coerulescens using molecular markers derived mainly from the Triticeae genome, conWrming the conservation of choromosomal location and gene order in both regions of the grass genomes (Bian et al 2004). Furthermore, considerable eVorts have been made in identifying the SI genes from various grass species, but neither the S nor Z genes have yet been cloned (Wehling et al 1994;Li et al 1994Li et al , 1997Langridge et al 1999;Baumann et al 2000;Gudu et al 2002;Hackauf and Wehling 2005;Yang et al 2008;Van Daele et al 2008).…”

“…Furthermore, considerable eVorts have been made in identifying the SI genes from various grass species, but neither the S nor Z genes have yet been cloned (Wehling et al 1994;Li et al 1994Li et al , 1997Langridge et al 1999;Baumann et al 2000;Gudu et al 2002;Hackauf and Wehling 2005;Yang et al 2008;Van Daele et al 2008). Bian et al (2004) proposed a map-based cloning strategy in Phalaris with the aid of information from the rice genome sequence. They delimited the S locus to a region on the map of 0.26 cM.…”