by Wagdy Sawahel, SciDev.Net
Scientists could transfer new genes into cultivated wheat crops
Researchers have shown that wild relatives of cultivated wheat exhibit resistance to a number of fungal diseases, and could provide a source of resistance genes to introduce into cultivated wheat.
They published their findings in August issue of the journal Plant Disease (Volume 91, Number 8, August 2007).
Lead researcher Brian Steffenson, plant pathologist at the US-based University of Minnesota, and colleagues have shown that there is a high level of disease resistance in samples of Sharon goatgrass (Aegilops sharonensis) collected from southern Lebanon and the Israeli Coastal Plain.
For example, they found that around 70 per cent of the goatgrass samples were resistant to a certain type of stem rust, a fungal disease that threatens much of the world's wheat crops (see Deadly wheat disease 'a threat to world food security').
Four out of 107 samples were highly resistant to most of the wheat fungal diseases tested for — powdery mildew, leaf rust, stem rust, stripe rust, tan spot and spot blotch.
Co-author of the paper, Yehoshua Aniksterat, of the Israel-based Institute for Cereal Crops Improvement at Tel Aviv University, told SciDev.Net that although it could be difficult — and take up to five years or more — they may be able to transfer genes from wild to cultivated wheat.
Steffenson told SciDev.Net that wild ancestors of cultivated plants often carry resistance to disease organisms.
He said the research project will continue to evaluate wild wheat and barley species for useful genes, not only for disease resistance but also those contributing to higher yield, nutritional quality and adaptation to harsh environments.
Rodomiro Ortiz, director of resource mobilisation at Mexico-based International Maize and Wheat Improvement Center (CIMMYT), told SciDev.Net the research reveals the genetic wealth available in wild relatives of important crops such as wheat and is useful for creating new cultivated crops.
But more research will be needed to confirm that these wild samples have broad-spectrum resistance and resistance to the most virulent forms of the pathogens, he said.
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Resistance of Sharon Goatgrass (Aegilops
sharonensis) to Fungal Diseases of
Wheat P. D. Olivera, Department of Plant Pathology, University of Minnesota, St. Paul 55108; J. A. Kolmer, United States Department of Agriculture–Agricultural Research Service, Cereal Disease Laboratory, Department of Plant Pathology, University of Minnesota, St. Paul 55108; Y. Anikster, Institute for Cereal Crops Improvement, Tel Aviv University, Ramat Aviv, Israel 69978; and B. J. Steffenson, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Disease 91:942-950. Accepted for publication 17 February 2007. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2007. |
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ABSTRACT Sharongoatgrass (Aegilops sharonensis) is a wild relative of wheat that is native to Israel and Lebanon. The importance of A. sharonensis as a source of new resistance genes for wheat warrants additional research on the characterization of accessions for economically important genes. Thus, the objectives of this study were to evaluate a collection of A. sharonensis accessions for resistance to seven important fungal diseases of wheat and assess the phenotypic diversity of the germplasm for disease reaction. The frequency of resistance in A. sharonensis was highest to powdery mildew (79 to 83%) and leaf rust (60 to 77%). Resistance to stem rust also was common, although the percentage of resistant accessions varied markedly depending on the pathogen race -- from 13% to race TTTT to 72% to race QCCJ. The frequency of resistance was intermediate to stripe rust (45%) and low to tan spot (15 to 29%) and spot blotch (0 to 34%). None of the A. sharonensis accessions was resistant to Fusarium head blight. Many of the accessions tested exhibited heterogeneous reactions (i.e., had both resistant and susceptible plants) to one or more of the diseases, suggesting that heterozygosity may be present at some resistance loci. Substantial variation was observed in the level of diversity to individual diseases because Shannon’s Equitability index ranged from 0.116 (for Fusarium head blight) to 0.994 (for tan spot). A high level of diversity was found both between and within collection sites. Moreover, differences in the geographic distribution of resistant accessions were observed. For example, accessions from northern Israel generally were less diverse and less resistant to leaf rust and stripe rust than accessions from more southern locations. Four A. sharonensis accessions were highly resistant to most of the diseases evaluated and may provide a source of unique resistance genes for introgression into cultivated wheat. Source: http://www.apsnet.org/pd/abstracts/2007/dau07ab.htm#extra |