Chromosomal assignment of gene sequences coding for protein disulphide isomerase (PDI) in wheat

Three different probes, obtained by PCR amplification and labelling of diff erent segments of a PDI cDNA clone from common wheat, were used to identify and assign to wheat chromosomes the gene sequences coding for protein disu lphide isomerase (PDI). One of these probes, containing the whole coding re gion except for a short segment coding for the C-terminal sequence, display ed defined and specific RFLP patterns. PDI gene sequences were consequently assigned to wheat chromosome arms 4BS, 4DS, 4AL and 1BS by Southern hybrid isation of EcoRI- HindIII- and BamHI-digested total DNA of nulli-tetrasomic and di-telosomic lines of Chinese Spring. This probe was also employed for assessing the restriction fragment length polymorphism in several hexaploi d and tetraploid cultivated wheats. These showed considerable conservation at PDI loci; in fact polymorphism was only observed for the chromosome 1B f ragment.