Histological characterization of wheat leaf rust resistance components in Thatcher isolines carrying race specific and race non-specific genes
S. Dugyala (1), P. Borowicz (1), R. Brueggeman (1), M. ACEVEDO (1). (1) North Dakota State University, Fargo, ND, U.S.A.
Leaf rust caused by <i>Puccinia triticina</i> is the most prevalent disease of wheat causing significant yield losses worldwide. Over 60 leaf rust resistance (<i>Lr</i>) genes have been designated but only a few are effective against the highly diverse North American <i>P. triticina</i> population. The use of broad, non-race specific resistance has been proposed as an alternative to achieve durable rust resistance. Post-haustorial resistance is generally involved in race specific resistance and is characterized by hypersensitive reaction (HR). Pre-haustorial resistance does not generally involve a HR, and is presumed to be more durable and may be involved in broad and non-race specific resistance. In this study, Thatcher near isogenic lines (NILs) carrying different <i>Lr</i> genes were characterized for pre and post-haustorial resistance components using florescence microscopy to races THBL, TSCD, TQBN at multiple time points during disease development. Resistance reactions to the pathogen were characterized by pathogen infection structure development, colony size, and plant and tissue responses. When challenged with avirulent races, NILs Tc-<i>Lr</i>9, -<i>Lr21</i> and <i>-Lr34</i> differed in number and time of fungal structure development compared to susceptible cv. Thatcher. The use of florescence microscopy provides new insights toward unraveling the complexities of the leaf rust host-pathogen interaction.
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