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Title: Genetic dissection of nonhost disease resistance in Arabidopsis thaliana
Author: Cui, Hang
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2006
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The Arabidopsis mutant eds1(enhanced disease susceptibility1), which is known to be defective in some aspects of R gene-mediated and basal disease resistance, is also compromised in nonhost disease resistance. A genetic modifier screen was carried out in order to identify further genes involved in nonhost resistance against Blumeria graminis f. sp tritici race Sav GH135 (Bgt1). Here, we report the isolation and characterization of two mutations, designated sed1 (suppressor of ed1) and sed2, both of which suppress eds1-mediated susceptibility towards Bgt1. The sed1eds1 mutant line exhibited restricted penetration of Bgt1 and a low formation frequency of haustoria and secondary hyphase. Loss of SED1 function also resulted in enhanced NHR against Bgt race W11S (Bgt2) and Blumeria graminis f. sp. hordei isolate 139 (Bgh) in an eds1 genetic background. However, sed1eds1 plants still maintained susceptibility against a broad-spectrum of host pathogens. Moreover, resistance against the nonhost bacterial pathogen Pseudomonas fluorescence was not affected, indicating that SED1is specifically required for establishment of NHR against powdery mildews. The sed2 mutant was initially isolated from a systemic acquired resistance (SAR) mutant screen using activated tagged populations of Arabidopsis and found to exhibit enhanced resistance to Hyaloperonospora parasitica Noco2. The sed2 mutant also suppressed eds1-mediated susceptibility towards Bgt1. The sed2eds1double mutant showed resistance against Bgt1 with regard to penetration and the formation of haustoria and secondary hyphae. Sed2eds1double mutants were also resistant to a series of host bacterial and oomycete pathogens. Thus, sed2 acts as a suppressor of eds1 establishing resistance against host and nonhost pathogens. This mutation mapped to a 400 kb interval between markers nga280 and T8L23 on chromosome I.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available