Genetics of Wheat Curl Mite Resistance in Wheat: Recombination of Cmc1 with the 6D Centromere

Abstract

Wheat streak mosaic is a destructive disease of common wheat (Tritium aestivum L. era. Thell.) that is vectored by the wheat curl mite, Erlophyes [Acerla] tulipae (Keifer). Resistance to colonization by this vector has been transferred to wheat from several host grasses but has not been reported in wheat perse. Resistance to wheat curl mite was transferred from Aegilops sqnarrosa L. to common wheat where it was shown to be conditioned by a single dominant gene (Cmc1) located on the short arm of Chromosome 6D. Compared with other, more alien transfers, the linkage block containing Cmcl is not expected to interfere with crossover and recombination on this chromosome. This study was undertaken to estimate recombination frequency in the chromosome segment proximal to the Cmcl locus. Recombination between Cmc1 and the 6D centromere among female gametes of plants monotelodisomic for Chromosome 6Ds occurred in 56 out of 107 cases (about 52.3%). The 95% confidence interval for this sample lies between 42.9 and 61.8. Correction of the lower limit for double crossovers showed (P > 0.95) that Cmcl was further than 64.3 centimorgans from the centromere of 6Ds.