Annual Progress Report on Malting Barley Research March, 2007

3.2. A barley nursery composed of differential cultivars will again be evaluated in the
Gallatin Valley and possibly the Flathead Valley of Montana where stripe rust of
barley appeared for the first time in 1996. Commercial cultivars/lines will be
evaluated for stripe rust reaction in areas were the fungus appears naturally.
Virulence types will be compared to stripe rust of barley from other locations. Wild
grasses will be surveyed for the presence of the fungus as soon as the snow cover has
melted and green tissue is visible.
3.3. We maintain several of isolates of Puccinia striiformis hordei, stripe rust of barley,
which have been isolated from the Gallatin Valley over the past few years. These
isolates are periodically increased and purified by single uredosorus isolation. The
virulence will be determined by the reaction of a set of differential cultivars, which
are also maintained at MSU. Inoculum as well as differential cultivars are available
to other research projects at MSU and other locations worldwide.
Isolates of numerous other barley pathogens are being maintained at MSU. They are
being utilized for class room demonstration, disease screenings and are also
available to other researchers.
4. Results
4.1. F1 populations from all but a few combinations of the malting cultivars Metcalfe and
Legacy are now available. Where the seed supply was sufficient an F1 reaction to
stripe rust has been determined on 10 seedlings (Tab.1). Most F1 populations gave, as
expected, a susceptible reaction. Quantitative resistance is usually based on a number
of recessive genes. We have long suspected that Bison 2-22 with high resistance to
barley stripe rust located on chromosome 7H is based on a mayor gene. F1 results
confirm this hypothesis. Since rust fungi are capable to mutate and overcome
monogenic resistance rather easily, this gene should not be used by itself, but
combined with other sources. Resistant reactions could also be observed on QTLs
located on chromosome 5H indicating some dominance in these loci.
The screened plant have been saved and transplanted. If time allows the first
backcrosses could be made in late spring of 2007. There is also some left over F1 seed
from all combination of Metcalfe and Legacy with the resistance donors.
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