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1999 STEEP III Final ReportRESEARCH PROJECT TITLE: Improved Methods for Evaluating Resistance To Cephalosporium Stripe of Wheat INVESTIGATORS:
PROJECT OBJECTIVES:
KEY WORDS: Cephalosporium stripe, conservation tillage, fungal toxins, molecular mapping STATEMENT OF PROBLEM: Cephalosporium stripe
has become a limiting factor for many Pacific Northwest wheat growers
in erosion-prone areas, especially when early planting and/or trashy fallow
are practiced. Burning or plowing stubble and delayed seeding can provide
substantial control of Cephalosporium stripe. However, these cultural
control methods conflict strongly with attempts to control soil erosion.
Though no soft white winter wheat cultivars show complete resistance to
Cephalosporium stripe, there is considerable variation in the degree of
resistance among cultivars. Levels of resistance currently available are
adequate to reduce inoculum levels over time and control the disease in
the long-term. However, identifying resistance in breeding programs remains
problematic. Expression of resistance is incomplete and environmentally
dependent. Further, the disease tends to be aggregated within fields,
thus requiring large plots to make useful comparisons, which is not possible
in early generations of cultivar development. ZONE OF INTEREST: Low and intermediate rainfall ABSTRACT OF RESEARCH FINDINGS: Though funds for
this project were not yet received at the time this report was written,
we have made some initial progress in anticipation of the project beginning.
These are listed by objective: Objective 1.
Optimization of Toxin Production - We have found that the rotary evaporation
procedure, a very time-consuming process, can be eliminated from the toxin
production protocol. This has greatly facilitated scaling-up production
of the toxin. Objective 2.
Toxin Purification and Characterization - The toxic activity has been
further fractionated to attain increased purity. Interestingly, some fractions
seem to induce chlorosis while others seem to induce wilting, and this
information may be of use in developing an optimum screen for resistance. Objective 3.
Genetics of Resistance in Pacific Northwest Cultivars - Progeny of crosses
between susceptible and moderately resistant parents have been harvested
and are being increased in the 1999-00 field season. In addition, lines
that may have higher levels of resistance have been identified, and these
may facilitate studies of the inheritance of resistance to Cephalosporium
stripe. Objective 4. Molecular Markers and Genetics of Resistance - Seed of the mapping population progeny have been increased for use in this project. In addition, we have begun efforts to evaluate mapping population progeny in direct assays with the pathogen. The ultimate outcome
of the project will be wheat cultivars with resistance to Cephalosporium
stripe combined with favorable quality, yield, and other important agronomic
characteristics. Such cultivars will greatly increase ability of wheat
growers to successfully implement conservation tillage practices in erosion-prone
areas. In the short-term, we will identify and exploit useable levels
of resistance in adapted germplasm. In the longer term, we will be able
to develop gene introgressions with potentially very high levels of resistance
from synthetic populations via molecular markers. INTERACTION WITH OTHER SCIENTISTS CONDUCTING RELATED ACTIVITY: Information regarding
the biology and control of Cephalosporium stripe is exchanged with other
pathologists in the Pacific Northwest, primarily Tim Murray (WSU) and
Dick Smiley (OSU). In addition, contact is maintained with wheat breeding
programs in Idaho, Oregon, and Washington to identify promising lines
for evaluation, and to provide breeding programs with information regarding
reactions of wheat cultivars and lines to Cephalosporium stripe. PUBLICATIONS AND PRESENTATIONS: none (new project). |
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 Contact
us: Hans Kok, (208)885-5971
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