Prehaustorial resistance to the wheat leaf rust fungus, Puccinia triticina, in Triticum monococcum (s.s.)

Diploid wheat, Triticum monococcum s.l., is a host for the wheat leaf rust fungus, Puccinia triticina. Some accessions have been reported to show a hi gh degree of prehaustorial resistance. This is non-hypersensitivity resista nce, which acts before the formation of haustoria by the pathogen. To asses s the frequency of prehaustorial resistance 598 accessions of diploid wheat were inoculated with the wheat leaf rust isolate Felix. Most T. monococcum s.s. accessions (84%) were resistant whereas all T. urartu and all but thr ee T. boeoticum accessions were susceptible. Histological components analys is revealed that a high percentage of prehaustorial resistance to P. tritic ina was found in only three T. monococcum accessions. No haustoria were obs erved in such infection units confirming the prehaustorial nature of the re sistance. Prehaustorial abortion of certain infection units in an accession always coincided with posthaustorial abortion of the other infection units .