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Resistance in winter wheat to fusari...

Horevaj, Peter.

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Resistance in winter wheat to fusarium head blight.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Resistance in winter wheat to fusarium head blight./
作者:	Horevaj, Peter.
面頁冊數:	103 p.
附註:	Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page: 2752.
Contained By:	Dissertation Abstracts International71-05B.
標題:	Biology, Botany. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3407356
ISBN:	9781109761740

Resistance in winter wheat to fusarium head blight.
Horevaj, Peter.

Resistance in winter wheat to fusarium head blight. - 103 p.

Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page: 2752.

Thesis (Ph.D.)--University of Arkansas, 2010.

Fusarium head blight (FHB), caused by the fungal pathogen Fusarium graminearum, is an important disease of wheat because it reduces yield and quality and because associated mycotoxins such as deoxynivalenol (DON) and nivalenol (NIV) contaminate grain, making it unfit for human or animal consumption. Developing resistant wheat cultivars is perceived to be the most effective means for managing FHB and reducing levels of mycotoxins in grain. F. graminearum strains producing mainly DON (DON chemotype) predominate in the U.S.; however, the recent discovery of strains producing mainly NIV (NIV chemotype) in the Midsouth requires resistance in wheat to both chemotypes. Development of wheat cultivars with adequate resistance has been difficult because resistance is controlled by several genes with small effects and because five components or mechanisms of resistance (resistance to initial infection, resistance to spread of the pathogen within a spike, resistance to kernel infection, tolerance, and resistance to mycotoxin accumulation in the grain) have been hypothesized. The objectives of this research were to characterize and quantify the components of resistance in winter wheat lines adapted to Arkansas, to improve methods for quantifying these components of resistance, and to determine if the resistances are also effective against the NIV chemotype of the pathogen. Fifteen lines with diverse sources of FHB resistance to the DON chemotype of F. graminearum and a susceptible check were evaluated in a series of field, greenhouse, and growth chamber experiments over four years. Significant levels of resistance to both initial infection, and spread within a spike were found in all 15 resistant wheat lines, and lines were more resistant to isolates of the NIV chemotype than to isolates of the DON chemotype. Therefore, using aggressive DON chemotype isolates to screen wheat lines for resistance also should select for resistance to NIV chemotype isolates. Standardizing inoculum and environmental conditions improved quantification of resistance to initial infection, and calculating the area under the disease progress curve from 7 to 21 days after inoculation enabled quantification of resistance to spread within a spike in the sane experiment, thereby increasing the efficiency of selection. Levels of mycotoxins in the grain of all resistant lines were significantly lower than the level in the susceptible check and were positively correlated with the percentage of scabby kernels. Therefore, selecting wheat lines for low levels of scabby kernels also should select for low levels of mycotoxins, thereby simplifying the selection for low mycotoxin levels in grain. The FHB resistances in these lines would have a significant impact on DON and NIV levels in grain if the resistances were incorporated into cultivars that replaced existing susceptible cultivars. Injecting florets with DON, demonstrated that FHB1, the most widely used resistance gene, has a unique mode of action and that measuring relative yield loss after DON injection may be a useful method for identifying lines with tolerance to FHB in the field. A real-time PCR technique was developed to quantify the level of kernel colonization by F. graminearum , and this represents a technological advance over visual ratings and other real-time PCR detection methodologies that do not measure fungal biomass.

ISBN: 9781109761740Subjects--Topical Terms:

1017825
Biology, Botany.

Resistance in winter wheat to fusarium head blight.
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520 $a Fusarium head blight (FHB), caused by the fungal pathogen Fusarium graminearum, is an important disease of wheat because it reduces yield and quality and because associated mycotoxins such as deoxynivalenol (DON) and nivalenol (NIV) contaminate grain, making it unfit for human or animal consumption. Developing resistant wheat cultivars is perceived to be the most effective means for managing FHB and reducing levels of mycotoxins in grain. F. graminearum strains producing mainly DON (DON chemotype) predominate in the U.S.; however, the recent discovery of strains producing mainly NIV (NIV chemotype) in the Midsouth requires resistance in wheat to both chemotypes. Development of wheat cultivars with adequate resistance has been difficult because resistance is controlled by several genes with small effects and because five components or mechanisms of resistance (resistance to initial infection, resistance to spread of the pathogen within a spike, resistance to kernel infection, tolerance, and resistance to mycotoxin accumulation in the grain) have been hypothesized. The objectives of this research were to characterize and quantify the components of resistance in winter wheat lines adapted to Arkansas, to improve methods for quantifying these components of resistance, and to determine if the resistances are also effective against the NIV chemotype of the pathogen. Fifteen lines with diverse sources of FHB resistance to the DON chemotype of F. graminearum and a susceptible check were evaluated in a series of field, greenhouse, and growth chamber experiments over four years. Significant levels of resistance to both initial infection, and spread within a spike were found in all 15 resistant wheat lines, and lines were more resistant to isolates of the NIV chemotype than to isolates of the DON chemotype. Therefore, using aggressive DON chemotype isolates to screen wheat lines for resistance also should select for resistance to NIV chemotype isolates. Standardizing inoculum and environmental conditions improved quantification of resistance to initial infection, and calculating the area under the disease progress curve from 7 to 21 days after inoculation enabled quantification of resistance to spread within a spike in the sane experiment, thereby increasing the efficiency of selection. Levels of mycotoxins in the grain of all resistant lines were significantly lower than the level in the susceptible check and were positively correlated with the percentage of scabby kernels. Therefore, selecting wheat lines for low levels of scabby kernels also should select for low levels of mycotoxins, thereby simplifying the selection for low mycotoxin levels in grain. The FHB resistances in these lines would have a significant impact on DON and NIV levels in grain if the resistances were incorporated into cultivars that replaced existing susceptible cultivars. Injecting florets with DON, demonstrated that FHB1, the most widely used resistance gene, has a unique mode of action and that measuring relative yield loss after DON injection may be a useful method for identifying lines with tolerance to FHB in the field. A real-time PCR technique was developed to quantify the level of kernel colonization by F. graminearum , and this represents a technological advance over visual ratings and other real-time PCR detection methodologies that do not measure fungal biomass.
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