Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Identification of wheat yellow
(stripe) rust pathotypes in Iran
F. Afshari
Seed and Plant Improvement Institute (SPII), Karaj, Islamic Republic of Iran
E-mail for correspondence: fafshari@hotmail.com
Abstract
Stripe rust in wheat caused by the fungus Puccinia striiformis f.sp. tritici is an
important disease in Iran. In order to determine the stripe rust races and use
the information in a breeding programme it is necessary to determine races
and virulence factors of the pathogen flora. In this study, 15 isolates of the
stripe rust pathogen were collected from different parts of Iran. Spores of each
isolate, after multiplication, were inoculated on an international standard
differential set in the greenhouse. According to the results, virulence on plant
with genes Yr2, Yr6, Yr7, Yr8, Yr9, Yr24, YrND and YrA was detected. The
majority of isolates with high frequency had virulence on plants with Yr2, Yr6,
Yr7, Yr9, YrA and Yr24 genes. No virulence was detected on plants with Yr1,
Yr3, Yr4, Yr5, Yr10, YrSP, YrCV, YrSU and YrSK.
Introduction
Common wheat (Triticum aestivum L.) is probably the most important of all
cultivated plants with respect to the nutrition of mankind because of its value
as an energy-rich food source.
Wheat is a host for many groups of parasitic fungi, bacteria, viruses and
insects. Major threats to wheat production on a worldwide basis come from
one or more of the three rust diseases. Yellow rust (stripe rust) caused by
Puccinia striiformis West. f.sp. tritici Eriks. and Henn. (Pst) is the most
important rust disease in Iran. The annual value of losses due to stripe rust in
Australia was estimated to be $AUS 139 million (Brennan and Murray, 1988).
In 1994, an estimated 15% (1.5 million tonne) yield loss was caused by yellow
rust in the national wheat crop in Iran (Torabi et al., 1995). The occurrence of
pathogenic variability in rust fungi led to considerable confusion and
disagreement among early researchers of rust diseases. For example, Rudorf
(1929; cited in Wellings, 1986) noted that some cultivars resistant in the USA
were susceptible in Germany. This was due presumably to variation in
pathotypes between geographical regions.