, Volume 179, Issue 1, pp 57–67 | Cite as

Prospects for functional analysis of effectors from cereal rust fungi

  • Chuntao Yin
  • Scot Hulbert


With the advancement of several Puccinia genome sequencing projects, along with gene expression data and methods for predicting secreted proteins, it is now possible to predict many effector proteins from the cereal rusts. Biological assays that can be conducted in a relatively high throughput fashion are necessary to assign specific functions, such as avirulence. Biolistic delivery of potential effectors is limited by the need to examine individual cells and delivery by Agrobacterium generally also affects small numbers of cells in grasses. An approach that has had some success in dicots is the use of bacterial systems to deliver proteins by their type III secretion systems (TTSS). Several bacterial systems were thus tested for their suitability in delivering effectors to wheat. Pseudomonas syringae DC3000 caused hypersensitive reactions (HR) when infiltrated into all tested wheat lines but only some barley lines. A variant strain with multiple effectors deleted showed a reduced HR on wheat lines. Pseudomonas fluorescens with an engineered TTSS system showed no HR in wheat lines but was able to deliver bacterial effectors AvrRpm1 and AvrRpt2 and the fungal toxin ToxA. Delivery of the effectors by P. fluorescens could be detected by HR or by staining for presence of hydrogen peroxide or callose deposits. The bacterial systems thus showed good potential for their ability to deliver foreign proteins into wheat cells.


Type III secretion system Pseudomonas syringae Pseudomonas fluorescens RNAi Wheat Barley 



This work was supported in part by National Institute of Food and Agriculture Grant No. 2010-65108-20568. We are grateful to Timothy Friesen for providing seeds of Langdon and the ToxA-insensitive mutant and Xianmin Chen for providing seeds of differential barley cultivars and differential wheat cultivars. Alan Collmer kindly provided P. syringae strains DC3000 and CUCPB5500 and the Pseudomonas fluorescens strains were provided by Jeff Chang. The pEDV6 and pEDV3 vectors were a gift from Jonathan Jones. We are also grateful to Zhaohui Liu, Justin Faris, and Timothy Friesen for supplying a clone of the ToxA gene and consultation on its use.


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Department of Plant PathologyWashington State UniversityPullmanUSA

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