TheHalocus of wheat: Identification of a polymorphic region for tracing grain hardness in crosses

Abstract

The grain softness proteins or friabilins are known to be composed of three main components: puroindoline a, puroindoline b, and GSP-1. cDNAs for GSP-1 have previously been mapped to group-5 chromosomes and their location on chromosome 5D is closely linked to the grain hardness (Ha) locus of hexaploid wheat. A genomic DNA clone containing the GSP-1 gene (wGSP1-A1) from hexaploid wheat has been identified by fluorescent in situ hybridization as having originated from the distal end of the short arm of chromosome 5A. A genomic clone containing the gene (wGSP1-D1) was also isolated from Aegilops tauschii, the donor of the D genome to bread wheat. There are no introns in the GSP-1 genes, and there is high sequence identity between wGSP1-A1 and wGSP1-D1 up to 1 kb 5' and 300 bp 3' to wGSP1-D1. However, regions further upstream and downstream of wGSP1-D1 share no significant sequence identity to corresponding sequences in wGSP1-A1. These regions therefore identified potentially valuable sequences for tracing the Ha locus through assaying polymorphic DNA sequences. The sequence from 300 to 500 bp 3' to wGSP1-D1 (wGSP1-D13) was mapped to the Ha locus in a mapping population. wGSP1-D13 was also tightly linked to genes for puroindoline a and puroindoline b which have been previously mapped to be at the Ha locus. In addition wGSP1-D13 was used to detect RFLPs between near isogenic soft and hard Falcon lines and in a random selection of soft and hard wheats.

Fine Mapping and Marker Development for the Crossability Gene SKr on Chromosome 5BS of Hexaploid Wheat (Triticum aestivum L.)

“…The 5B homeologous GSP locus is linked closely to the crossability gene SKr: The rice homologous gene to GBR0233 near SKr, Os12g44150, is separated by only two genes in the rice genome annotation from a group of genes (Os12g44180-Os12g44250) that were identified previously as orthologous to the regions carrying the grain softness protein (GSP) gene on the short arm of wheat chromosomes group 5 (Sourdille et al 1996;Turner et al 1999;Igrejas et al 2002;Chantret et al 2004) (Figure 4) and the short arm of chromosome 5H in barley (Caldwell et al 2004). To assess whether SKr is in the vicinity of the GSP locus on 5B and derive new markers, SSR and insertion site-based polymorphism (ISBP) markers (Paux et al 2006) were designed from the sequence of the BAC clone 1793L02 (GenBank acc.…”

Single-copy gene fluorescence in situ hybridization and genome analysis: Acc-2 loci mark evolutionary chromosomal rearrangements in wheat

“…This procedure does not need detection and blocking steps, which were previously being used in indirect FISH to visualize gene clusters and repeats (Mukai et al 1993;Pedersen and Langridge 1997;Turner et al 1999;Li et al 2003;Turnbull et al 2003;Szakacs and Molnar-Lang 2007;Cuadrado et al 2008a, b) or a signal-amplification step in tyramide-FISH (Perez et al 2009). …”

“…In wheat, gene-specific probes and probes for tandem repeats, including oligonucleotide probes, were used in indirect FISH with blocking to detect tandem repeats and gene clusters (Mukai et al 1993;Pedersen and Langridge 1997;Turner et al 1999;Li et al 2003;Turnbull et al 2003;Szakacs and Molnar-Lang 2007;Cuadrado et al 2008 a, b). Indirect FISH uses nonfluorescent chemicals for labeling and needs an additional detection step for visualizing the hybridization site and amplifying of the signal.…”

Complementation of sugary-1 Phenotype in Rice Endosperm with the Wheat Isoamylase1 Gene Supports a Direct Role for Isoamylase1 in Amylopectin Biosynthesis

“…DBEI clone and chromosome marker probes were labeled with digoxigenin-11-dUTP and biotin-16-dUTP, respectively, by nick translocation according to Mukai et al (1993). Fluorescence in situ hybridization analysis was carried out as described by Turner et al (1999).…”