Physical mapping resources for large plant genomes: radiation hybrids for wheat D-genome progenitor Aegilops tauschii.

Background: Development of a high quality reference sequence is a daunting task in crops like wheat with large (~17Gb), highly repetitive (>80%) and polyploid genome. To achieve complete sequence assembly of such genomes, development of a high quality physical map is a necessary first step. However, due to the lack of recombination in certain regions of the chromosomes, genetic mapping, which uses recombination frequency to map marker loci, alone is not sufficient to develop high quality marker scaffolds for a sequence ready physical map.

Barley necrotic locus nec1 encodes the cyclic nucleotide-gated ion channel 4 homologous to the Arabidopsis HLM1.

Barley homolog of the Arabidopsis necrotic (disease lesion mimic) mutant HLM1 that encodes the cyclic nucleotide-gated ion channel 4 was cloned. Barley gene was mapped genetically to the known necrotic locus nec1 and subsequent sequence analysis identified mutations in five available nec1 alleles confirming barley homolog of Arabidopsis HLM1 as the NEC1 gene. Two fast neutron (FN) induced mutants had extensive deletions in the gene, while two previously described nec1 alleles had either a STOP codon in exon 1 or a MITE insertion in intron 2 which caused alternative splicing, frame shift and production of a predicted non-functional protein.