UTILIZATION OF DELETIONS TO LOCALIZE A GENE FOR RESISTANCE TO THE CEREAL CYST-NEMATODE, HETERODERA-AVENAE, ON AN AEGILOPS VENTRICOSA CHROMOSOME

A previous RFLP analysis showed that the Aegilops ventricosa chromosom e 6M(V) which compensates for the absence of 6D in 6M(V) (6D) wheat su bstitution lines was a 2/6 translocated chromosome, either 2S-6S.6L or 2S-6L.6S. The distal part of its long arm consists of a translocated segment belonging to homoeologous group 2. Chromosome 6M(V) carries a gene(s) for resistance to cereal cyst nematode. In order to define the part of 6M(V) (2S or 6S or 6L) involved in this resistance, addition lines with a 6M(V) deleted either for its short arm or for the distal part of its long arm were evaluated. It was shown that the gene(s) is carried by the group 2 translocated segment. The hypothesis that the g ene(s) could be allelic to Cre2, another gene conferring resistance to the nematode introduced into the wheat complement from Ae. ventricosa is discussed.