Trends in Plant Science
Volume 7, Issue 10, 1 October 2002, Pages 425-427
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Research update
The Arabidopsis RRS1-R disease resistance gene – uncovering the plant's nucleus as the new battlefield of plant defense?

https://doi.org/10.1016/S1360-1385(02)02334-8Get rights and content

Abstract

The isolation of over 30 plant disease-resistance genes revealed that most genes encode putatively cytoplasmic proteins with a nucleotide-binding site (NBS) and a leucine-rich repeat (LRR). However, the recent isolation of the Arabidopsis RRS1-R gene has uncovered a novel NBS–LRR subtype that harbors a C-terminal extension with a putative nuclear localization signal and a DNA-binding domain that is characteristic of the WRKY transcription factor family. This suggests that RRS1-R, unlike any other known R protein, is targeted to the nucleus to fulfill its function.

Section snippets

Isolation of Arabidopsis RRS1-R uncovers a new class of R genes

The recent isolation of the Arabidopsis RRS1-R gene, which confers resistance to the bacterial phytopathogen Ralstonia solanacearum, has uncovered a new member of the TIR–NBS–LRR R protein class. RRS1-R has a C-terminal extension with a putative nuclear localization signal (NLS) and a WRKY domain [5].

Genetic studies of RRS1-R showed that it is not only exceptional in its structure but also in its Mendelian inheritance. In contrast to all other TIR–NBS–LRR-encoding R genes, which act in a

Novel R protein domains in RRS1-R and their putative function

What can be deduced from the molecular architecture of RRS1-R? Significantly, NLS and WRKY domains have not been discovered in any other R protein to date. NLSs are short amino acid stretches that are necessary and sufficient for nuclear targeting of a given protein [8]. The WRKY domain is a highly conserved DNA-binding module that interacts with a cognate TGAC nucleotide core sequence (termed W-box). Interestingly, the W-box is prominent in many pathogen-responsive promoters [9]. The presence

Ralstonia sequencing project uncovers potential Avr-RRS1-R candidates

The Avr component triggering RRS1-R-mediated defense has not yet been defined. However, RRS1-R mediates broad-spectrum resistance to multiple Ralstonia solanacearum strains, which suggests that this plant R protein mediates detection of an Avr family that is highly conserved within the genus Ralstonia. Recent completion of the Ralstonia solanacearum genome sequence [12] has uncovered homologs of two well known Avr classes, the AvrBs3 and AvrRxv/YopJ families [13]. The presence of NLS signatures

Acknowledgements

I am grateful to Desmond Bradley, Sebastian Schornack, Daniela Büttner, Jason Rudd and Ulla Bonas for helpful comments on the manuscript. Work in the laboratory was supported by grants of the Deutsche Forschungsgemeinschaft (SFB 363 and LA 1338/1–1).

References (16)

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