Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum and other Fusarium species, is a major disease problem for wheat production worldwide. To combat this problem, large-scale breeding efforts have been established. Although progress has been made through standard breeding approaches, the level of resistance attained is insufficient to withstand epidemic conditions. Genetic engineering provides an alternative approach to enhance the level of resistance. Many defense response genes are induced in wheat during F. graminearum infection and may play a role in reducing FHB. The objectives of this study were (1) to develop transgenic wheat overexpressing the defense response genes α-1-purothionin, thaumatin-like protein 1 (tlp-1), and β-1,3-glucanase; and (2) to test the resultant transgenic wheat lines against F. graminearum infection under greenhouse and field conditions. Using the wheat cultivar Bobwhite, we developed one, two, and four lines carrying the α-1-purothionin, tlp-1, and β-1,3-glucanase transgenes, respectively, that had statistically significant reductions in FHB severity in greenhouse evaluations. We tested these seven transgenic lines under field conditions for percent FHB disease severity, deoxynivalenol (DON) mycotoxin accumulation, and percent visually scabby kernels (VSK). Six of the seven lines differed from the nontransgenic parental Bobwhite line for at least one of the disease traits. A β-1,3-glucanase transgenic line had enhanced resistance, showing lower FHB severity, DON concentration, and percent VSK compared to Bobwhite. Taken together, the results showed that overexpression of defense response genes in wheat could enhance the FHB resistance in both greenhouse and field conditions.
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Acknowledgements We are most grateful to Dr. Tom Clemente and Shirley Sato of the University of Nebraska and to Drs. Ann Blechl, and Pat Okubara USDA-ARS, Albany, CA for their advise and assistance in generating the transgenic wheat plants. We are also grateful to Drs. Blechl, Okubara and Kent McCue and for providing the pKM1 and pUBK BglII transformation constructs. We thank Dr. John Mundy of the Carlsberg Research Laboratory, Copenhagen, Denmark and Dr. David Collinge of the Department of Plant Pathology, Royal Veterinary and Agricultural University, Copenhagen, Denmark for providing barley β- 1,3-glucanase and tlp-1 cDNAs, respectively. We also thank Dr. Peter Quail of the Plant Gene Expression Center, University of California at Berkeley for providing the pAHC25 and pAHC17 plasmids. We are indebted to Keith Hansen, Adam Dobberfuhl, Dong Tuong, Sarah Jutila, Alissa Cyrus, John Wiersma, Amar Elakkad, Karen Wennberg and Yanhong Dong for excellent technical assistance. Sanghyun Shin was supported by the Korea Research Foundation (KRF-2005-000-10035). This work was supported by grants from the U.S. Wheat and Barley Scab Initiative, Minnesota State Scab Initiative, and Minnesota Wheat Research and Promotion Council.
- Fusarium graminearum
- Fusarium head blight
- Transgenic wheat
- Triticum aestivum