The evolution of disease resistance genes

Richter, Todd; Ronald, Pamela C.

doi:10.1007/978-94-011-4221-2_10

Cited by 64 publications

(75 citation statements)

References 81 publications

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“…Identification of the Pi9 multigene family is consistent with the findings from other R loci where the R genes are commonly clustered in the genome (Michelmore and Meyers 1998;Richter and Ronald 2000;Hulbert et al 2001;Bai et al 2002;Wei et al 2002;Sun et al 2004). From the viewpoint of plant evolution, the clustering of highly homologous R genes at a locus provides a variety of opportunities for plants to evolve new specificities of resistance when the corresponding AVR gene in the pathogen has mutated.…”

Section: Discussionsupporting

confidence: 79%

“…Clusters of R genes have been identified in diverse plant species (Islam and Shepherd 1991;Jones et al 1993;Song et al 1995Song et al , 1997Kunkel 1996;Salmeron et al 1996;Ellis et al 1997;Meyers et al 1998;Michelmore and Meyers 1998;Richter and Ronald 2000;Wei et al 2002). The majority of the 149 NBS-LRR genes occurring in the Arabidopsis genome are clustered (Meyers et al 2003) as are the .600 NBS-LRR genes identified in the rice genome (Bai et al 2002).…”

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confidence: 99%

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The Broad-Spectrum Blast Resistance Gene Pi9 Encodes a Nucleotide-Binding Site–Leucine-Rich Repeat Protein and Is a Member of a Multigene Family in Rice

et al. 2006

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The broad-spectrum rice blast resistance gene Pi9 was cloned using a map-based cloning strategy. Sequencing of a 76-kb bacterial artificial chromosome (BAC) contig spanning the Pi9 locus led to identification of six tandemly arranged resistance-like genes with a nucleotide-binding site (NBS) and leucine-rich repeats (LRRs) (Nbs1-Pi9-Nbs6-Pi9). Analysis of selected Pi9 deletion mutants and transformation of a 45-kb fragment from the BAC contig into the susceptible rice cultivar TP309 narrowed down Pi9 to the candidate genes Nbs2-Pi9 and Nbs3-Pi9. Disease evaluation of the transgenic lines carrying the individual candidate genes confirmed that Nbs2-Pi9 is the Pi9 gene. Sequence comparison analysis revealed that the six paralogs at the Pi9 locus belong to four classes and gene duplication might be one of the major evolutionary forces contributing to the formation of the NBS-LRR gene cluster. Semiquantitative reverse transcriptase (RT)-PCR analysis showed that Pi9 was constitutively expressed in the Pi9-resistant plants and was not induced by blast infection. The cloned Pi9 gene provides a starting point to elucidate the molecular basis of the broadspectrum disease resistance and the evolutionary mechanisms of blast resistance gene clusters in rice.

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Section: Discussionsupporting

confidence: 79%

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confidence: 99%

The Broad-Spectrum Blast Resistance Gene Pi9 Encodes a Nucleotide-Binding Site–Leucine-Rich Repeat Protein and Is a Member of a Multigene Family in Rice

et al. 2006

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“…WAK gene family is greatly expanded in the rice with the identification of 125 WAKs (OsWAKs) in the sequenced rice genome . Such an increase in size of tandemly repeated and clustered gene families is correlated with a role in disease resistance and response to environmental stresses (Richter and Ronald 2000;Lespinet et al 2002). However, functions of these putative OsWAK genes are yet to be determined.…”

Section: Functional Studies Of Different Wak Members Inmentioning

confidence: 99%

RNAi mediated silencing of a wall associated kinase, OsiWAK1 in Oryza sativa results in impaired root development and sterility due to anther indehiscence

Kanneganti

Gupta

2011

Physiol Mol Biol Plants

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The Wall-Associated Kinase, one of the receptorlike kinase (RLK) gene families in plant, plays important roles in cell expansion, pathogen resistance and heavy metal stress tolerance in Arabidopsis thaliana. Here, we isolated a cDNA encoding a novel WAK from indica rice and designated as OsiWAK1 (Oryza sativa indica WAK-1). In this study, the RNAi construct with OsiWAK1 gene cloned in sense and antisense orientation separated by a functional intron under constitutive promoter, was introduced through biolistic gene gun method into the rice cultivar "IR-50" to determine the effect of OsiWAK1 transcript silencing on rice plant development. Examination of the transgenic plants reveals that OsiWAK1 transcript silencing in rice results in dwarf plants because of the reduction in the size of leaves, flag-leaves, internodes and panicle. The development of root primordia during germination, root hairs and lateral rooting was also effected. Microscopic analysis revealed that the decrease in size is due to reduction in the cell size but not the number of cells. In addition, the transgenic plants also exhibited sterile phenotype due to anther indehiscence and 40 % reduction in pollen viability. These data suggest that OsiWAK1 may play an important role in rice plant growth and development.

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“…Possible substrates for somatic recombination events in plants are the large number of disease-resistance genes involved in the perception of pathogen attack that are spread in clusters throughout the genome 26,27 . Their evolution and the generation of novel dis- ease-resistance specificities has often been associated with recombination events 28,29 , but the timescale and mechanism of these events is not known. Modulation of the rate of genetic change by environmental stress may be important for the longterm adaptation of populations to changing environments [1][2][3] .…”

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Pathogen stress increases somatic recombination frequency in Arabidopsis

et al. 2002

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Evolution is based on genetic variability and subsequent phenotypic selection. Mechanisms that modulate the rate of mutation according to environmental cues, and thus control the balance between genetic stability and flexibility, might provide a distinct evolutionary advantage 1-4 . Stress-induced mutations stimulated by unfavorable environments, and possible mechanisms for their induction, have been described for several organisms 2-4 , but research in this area has mainly focused on microorganisms. We have analyzed the influence of adverse environmental conditions on the genetic stability of the higher plant Arabidopsis thaliana. Here we show that a biotic stress factorattack by the oomycete pathogen Peronospora parasiticacan stimulate somatic recombination in Arabidopsis. The same effect was observed when plant pathogen-defense mechanisms were activated by the chemicals 2,6-dichloroisonicotinic acid (INA) or benzothiadiazole (BTH), or by a mutation (cim3). Together with previous studies of recombination induced by abiotic factors, these findings suggest that increased somatic recombination is a general stress response in plants. The increased genetic flexibility might facilitate evolutionary adaptation of plant populations to stressful environments.In plants, somatic recombination events are an important cause of genetic variability 5 , and, as plants lack a predetermined germ line, may also affect genetic composition of the progeny 6 . A variety of genotoxic factors, such as DNA-damaging chemicals, γ-irradiation and UV-B irradiation 7-10 , stimulate somatic recombination, an important pathway for the repair of DNA lesions in plants 5 . In addition, abiotic stress factors like heat and increased salinity seem to increase somatic recombination 7,8 . It is not known, however, whether biotic stress affects recombination and whether increased recombination might therefore be a general stress response in plants. We examined whether exposure to pathogens, a major biotic stress factor for plants, affects plant genome stability. To measure somatic recombination in whole plants, we used Arabidopsis lines carrying reporter transgenes that allowed visual detection of recombination events (Fig. 1) [8][9][10][11][12] . By testing populations of genetically identical plants grown under different conditions, this quantitative assay allowed us to determine the average recombination frequency per plant at the reporter gene locus and thus measure the influence of pathogen stress on genome stability.We sprayed seedlings of Arabidopsis recombination reporter line 651 (ref. 8) with a spore suspension of P. parasitica isolate EMWA 13 , which resulted in localized necrotic lesions at the points of attempted penetration but no further proliferation of the pathogen, as detected by microscopic observation (data not shown). This suggests the activation of plant defense mechanisms [14][15][16] . There was no macroscopic difference in appearance or growth of infected or uninfected plants. The infected plants showed a significant (P<0.0...

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The evolution of disease resistance genes

Cited by 64 publications

References 81 publications

The Broad-Spectrum Blast Resistance Gene Pi9 Encodes a Nucleotide-Binding Site–Leucine-Rich Repeat Protein and Is a Member of a Multigene Family in Rice

The Broad-Spectrum Blast Resistance Gene Pi9 Encodes a Nucleotide-Binding Site–Leucine-Rich Repeat Protein and Is a Member of a Multigene Family in Rice

RNAi mediated silencing of a wall associated kinase, OsiWAK1 in Oryza sativa results in impaired root development and sterility due to anther indehiscence

Pathogen stress increases somatic recombination frequency in Arabidopsis

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