A Medicago truncatula resistance to rust (rer) mutant displays enhanced resistance to Phakopsora pachyrhizi but not to necrotrophic fungal pathogens

Asian soybean rust caused by the fungus Phakopsora pachyrhizi is one of the most devastating foliar diseases affecting soybeans grown worldwide. Understanding the plant defense mechanisms and signaling pathways to P. pachyrhizi would assist in development of resistant plants. The most common form of...

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Bibliographic Details
Published in:Phytopathology 2010-06, Vol.100 (6), p.S54-S54
Main Authors: Ishiga, Y, Mittal, S, Uppalapati, SR, Doraiswamy, V, Schultheiss, H, Mysore, K S
Format: Article
Language:English
Subjects:
Colletotrichum trifolii
Medicago truncatula
Phakopsora pachyrhizi
Phoma
Sclerotinia sclerotiorum
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Summary:Asian soybean rust caused by the fungus Phakopsora pachyrhizi is one of the most devastating foliar diseases affecting soybeans grown worldwide. Understanding the plant defense mechanisms and signaling pathways to P. pachyrhizi would assist in development of resistant plants. The most common form of plant defense mechanism against potential pathogens in nature is nonhost resistance. Medicago truncatula is a model plant species for legumes, and shows nonhost resistance response to P. pachyrhizi. To identify M. truncatula mutants with altered resistance to P. pachyrhizi, we have established a forward-genetic screen of M. truncatula Tnt1 insertion lines. Screening of more than 1000 Tnt1 lines identified several interesting mutant phenotypes. Tnt1 insertion mutant of one of the mutant, rer (Resistance to rust), showed resistance to P. pachyrhizi by supporting less spore adhesion and germ-tube elongation. Further, rer mutant showed resistance to hemibiotrophic pathogen, Colletotrichum trifolii, but not to necrotrophic pathogens, Phoma medicaginis and Sclerotinia sclerotiorum. Interestingly, rer mutant has five leaves and shows less leaf surface hydrophobicity, suggesting that chemical or physical surface signals of rer mutant may play an important role in altered P. pachyrhizi spore adhesion and infection structure formation leading to enhanced resistance.
ISSN:0031-949X