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United States Department of Agriculture

Agricultural Research Service

Title: THE TOMATO RESISTANCE PROTEIN BS4 IS A PREDICTED NON-NUCLEAR TIR-NB-LRR PROTEIN THAT MEDIATES DEFENSE RESPONSES TO SEVERELY TRUNCATED DERIVATIVES OF AVRBS4 AND OVEREXPRESSED AVRBS3)

Author
item Schornack, Sebestian
item Ballvora, Agim
item Gurlebeck, Doreen
item Peart, Jack
item Ganal, Martin
item Baker, Barbara
item Bonas, Ulla
item Lahaye, Thomas

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2003
Publication Date: 11/14/2003
Citation: Schornack, S., Ballvora, A., Gurlebeck, D., Peart, J., Ganal, M., Baker, B.J., Bonas, U., Lahaye, T. 2003. The tomato resistance protein Bs4 is a predicted non-nuclear TIR-NB-LRR protein that mediates defense responses to severely truncated derivatives of AvrBs4 and overexpressed AvrBs3. Plant Journal 37(1) 46-60.

Interpretive Summary: The Lycopersicon esculentum Bs4 resistance (R) gene specifies recognition of Xanthomonas campestris pv. vesicatoria (Xcv) strains that express the cognate AvrBs4 avirulence protein. Bs4 was isolated by positional cloning and is predicted to encode a nucleotide-binding leucine-rich repeat (NB-LRR) protein that is homologous to tobacco N and potato Y-1 resistance proteins. Transcript studies revealed intron retention in Bs4 transcripts. Yet, an intron- However, a direct interaction was not observed. Defense signaling of the Bs4-governed reaction was studied in Nicotiana benthamiana by virus-induced gene silencing and showed that Bs4-mediated resistance is EDS1- and SGT1-dependent.

Technical Abstract: The Lycopersicon esculentum Bs4 resistance (R) gene specifies recognition of Xanthomonas campestris pv. vesicatoria (Xcv) strains that express the cognate AvrBs4 avirulence protein. Bs4 was isolated by positional cloning and is predicted to encode a nucleotide-binding leucine-rich repeat (NB-LRR) protein that is homologous to tobacco N and potato Y-1 resistance proteins. Xcv infection tests demonstrate that Bs4 confers perception of AvrBs4 but not the 97% identical AvrBs3 protein. However, when delivered via Agrobacterium T-DNA transfer, both, avrBs4 and avrBs3 trigger a Bs4-dependent hypersensitive response, indicating that naturally occurring AvrBs3-homologues provide a unique experimental platform for molecular dissection of recognition specificity. Transcript studies revealed intron retention in Bs4 transcripts. Yet, an intron-deprived Bs4 derivative still mediates AvrBs4 detection, suggesting that the identified splice variants are not crucial to resistance. The L. pennellii bs4 allele, which is >98% identical to L. esculentum Bs4, has a Bs4-like exon-intron structure with exception of a splice polymorphism in intron 2 that causes truncation of the predicted bs4 protein. To test if the receptor-ligand model is a valid molecular description of Bs4-mediated AvrBs4 perception, we conducted yeast two-hybrid studies. However, a direct interaction was not observed. Defense signaling of the Bs4-governed reaction was studied in Nicotiana benthamiana by virus-induced gene silencing and showed that Bs4-mediated resistance is EDS1- and SGT1-dependent.

Last Modified: 8/24/2016
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