Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Artificial inoculation techniques in screening for resistance
to yellow rust
A. Yahyaoui, M. Al Ahmed, Z. Alamdar, K. Nazari and M. Naimi
ICARDA, Aleppo, Syria
Screening for host resistance is one of the major activities undertaken by
ICARDA wheat pathology and breeding programmes. Breeding nurseries are
screened for yellow rust resistance under artificial inoculation in greenhouse
and field conditions. Proper techniques to ensure adequate infection levels are
important in the selection process to identify resistance to yellow rust. At
ICARDA, all breeding nurseries are evaluated each year at seedling and adult
growth stages in the greenhouse and under field conditions. Yellow rust
inoculum from Syrian yellow rust populations is increased and maintained in
the laboratory for inoculation. Single pustules are multiplied and used for race
analysis. Inoculation with single races is conducted at seedling growth stages
in a controlled environment for selected wheat germplasm. Mixed and singlespore
cultures are vacuum dried and stored at -80°C for long-term storage or
maintained in a refrigerator at 10°C for short-term storage (6–12 months). To
ensure proper infection, stored spores are increased on the universal
susceptible cv. Morocco, then used for field and greenhouse inoculations.
Yellow rust inoculum is composed of prevalent races that occur in Syria and
are used as bulk inoculum to eventually expose wheat genotypes to varied
pathogen virulences.