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Open Access Highly Accessed Research article

Arabidopsis nonhost resistance gene PSS1 confers immunity against an oomycete and a fungal pathogen but not a bacterial pathogen that cause diseases in soybean

Rishi Sumit12, Binod B Sahu1, Min Xu13, Devinder Sandhu14 and Madan K Bhattacharyya12*

Author Affiliations

1 Department of Agronomy, Iowa State University, Ames, IA, 50011, USA

2 Molecular Cellular and Developmental Biology Interdepartmental Graduate program, Iowa State University, Ames, IA, 50011, USA

3 Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, 94720, USA

4 Biology Department, University of Wisconsin, Stevens Point, Wisconsin, 54481, USA

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BMC Plant Biology 2012, 12:87  doi:10.1186/1471-2229-12-87

Published: 13 June 2012

Abstract

Background

Nonhost resistance (NHR) provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Three Arabidopsis thaliana PEN (penetration deficient) genes, PEN1, 2 and 3 have been shown to provide NHR against the barley pathogen Blumeria graminis f. sp. hordei at the prehaustorial level. Arabidopsis pen1-1 mutant lacking the PEN1 gene is penetrated by the hemibiotrophic oomycete pathogen Phytophthora sojae, the causal organism of the root and stem rot disease in soybean. We investigated if there is any novel nonhost resistance mechanism in Arabidopsis against the soybean pathogen, P. sojae.

Results

The

    P.
    s
ojae
    s
usceptible (pss) 1 mutant was identified by screening a mutant population created in the Arabidopsis pen1-1 mutant that lacks penetration resistance against the non adapted barley biotrophic fungal pathogen, Blumeria graminis f. sp. hordei. Segregation data suggested that PEN1 is not epistatic to PSS1. Responses of pss1 and pen1-1 to P. sojae invasion were distinct and suggest that PSS1 may act at both pre- and post-haustorial levels, while PEN1 acts at the pre-haustorial level against this soybean pathogen. Therefore, PSS1 encodes a new form of nonhost resistance. The pss1 mutant is also infected by the necrotrophic fungal pathogen, Fusarium virguliforme, which causes sudden death syndrome in soybean. Thus, a common NHR mechanism is operative in Arabidopsis against both hemibiotrophic oomycetes and necrotrophic fungal pathogens that are pathogenic to soybean. However, PSS1 does not play any role in immunity against the bacterial pathogen, Pseudomonas syringae pv. glycinea, that causes bacterial blight in soybean. We mapped PSS1 to a region very close to the southern telomere of chromosome 3 that carries no known disease resistance genes.

Conclusions

The study revealed that Arabidopsis PSS1 is a novel nonhost resistance gene that confers a new form of nonhost resistance against both a hemibiotrophic oomycete pathogen, P. sojae and a necrotrophic fungal pathogen, F. virguliforme that cause diseases in soybean. However, this gene does not play any role in the immunity of Arabidopsis to the bacterial pathogen, P. syringae pv. glycinea, which causes bacterial blight in soybean. Identification and further characterization of the PSS1 gene would provide further insights into a new form of nonhost resistance in Arabidopsis, which could be utilized in improving resistance of soybean to two serious pathogens.

Keywords:
Phytophthorasojaesusceptible (pss1); Sequence-based polymorphic (SBP) marker; Fusarium virguliforme; Phytophthora sojae; Pseudomonas syringae pv. glycinea