Abstract only

Leaf rust is a significant yield-limiting factor in durum wheat. New races have overcome the resistance of numerous commercial durum cultivars in some countries. Consequently, the search for, and genetic characterization of, globally effective sources of resistance has become a priority at CIMMYT. Six resistance sources were identified through multi-race testing and each source was crossed to two susceptible lines. Phenotyping of rust reaction was conducted in the field with a mixture of prevalent Mexican races. The F1s and 140 to 230 F3 families were assessed to determine dominance, the number of genes involved, and their modes of action. Allelism tests were conducted to determine the relationship between the different sources and with other known genes used in the CIMMYT program (LrCamayo, Lr61). Phenotypic analyses suggested that Moroccan cv. Amria, ICARDA lines Geromtel_1 and Tunsyr_2, and French cv. Byblos each carry single dominant genes. French cv. Arnacoris and Italian cultivar Saragolla each carry two recessive genes. Results from the allelism tests suggested that the genes from Geromtel_1 and Tunsyr_2 were either allelic or closely linked to each other and to Lr61. All the other sources were characterized by genes that are likely to be different from each other and from those common in CIMMYT germplasm. Further seedling stage evaluations of these populations are continuing along with initiation of molecular mapping of the monogenic resistances.

Global Wheat Program

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INT3176|INT2585

CIMMYT Staff Publications Collection