Contrasting modes of evolution acting on the complex N locus for rust resistance in flax
TLDR
It is suggested that the re-assortment of variation by recombination/gene conversion at this locus is limited by the degree of sequence identity between genes.Abstract:
Three rust resistance specificities, N, N1 and N2, map to the complex N locus of flax. We used a degenerate PCR approach, with primers directed to the nucleotide binding site (NBS) domain characteristic of many plant resistance genes, to isolate resistance gene analogs (RGAs) from flax. One RGA clone detected RFLPs co-segregating with alleles of the N locus. With this probe we isolated four related genes that occur within a 30kbp region and encode proteins with NBS and leucine-rich repeat (LRR) domains and N-terminal Toll/Interleukin-1 Receptor homology (TIR) domains. One of these four genes was identified as the N resistance gene by sequence analysis of three mutant alleles and by transgenic expression. We isolated homologous genes from two flax lines containing the N1 or N2 specificities and from flax lines carrying no N locus resistance specificities. Analysis of shared polymorphisms among this set of 18 N locus sequences revealed three groups of genes with independent lineages. Sequence exchanges have only occurred between genes within each group, but not between groups. Two of the groups contain only one sequence from each haplotype and probably represent orthologous genes. However, the third group contains two genes from each haplotype. We suggest that the re-assortment of variation by recombination/gene conversion at this locus is limited by the degree of sequence identity between genes.read more
Citations
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Fungal Effector Proteins
TL;DR: Variation observed among fungal effectors shows two types of selection that appear to relate to whether they interact directly or indirectly with their cognate resistance proteins, which seem to favor point mutations in effector genes and amino acid substitutions.
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Haustorially Expressed Secreted Proteins from Flax Rust Are Highly Enriched for Avirulence Elicitors
Ann-Maree Catanzariti,Ann-Maree Catanzariti,Peter N. Dodds,Gregory J. Lawrence,Michael Ayliffe,Jeffrey G. Ellis +5 more
TL;DR: In this article, the authors identified genes encoding haustorially expressed secreted proteins (HESPs) by screening a flax rust-specific cDNA library and identifying 21 HESPs, one corresponding to the AvrL567 gene.
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RXLR-Mediated Entry of Phytophthora sojae Effector Avr1b into Soybean Cells Does Not Require Pathogen-Encoded Machinery
Daolong Dou,Shiv D. Kale,Xia Wang,Rays H. Y. Jiang,Nathan A. Bruce,Felipe D. Arredondo,Xuemin Zhang,Brett M. Tyler +7 more
TL;DR: It is shown that a pair of sequence motifs, RXLR and dEER, plus surrounding sequences, are both necessary and sufficient to deliver the protein into plant cells and indicates that the >370 RXLR-dEER–containing proteins encoded in the genome sequence of P. sojae are candidate effectors.
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The Melampsora lini AvrL567 avirulence genes are expressed in haustoria and their products are recognized inside plant cells
TL;DR: Differences in the three AvrL567 protein sequences result from diversifying selection, which is consistent with a coevolutionary arms race.
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Plant disease resistance genes: Current status and future directions
Mayank Anand Gururani,Jelli Venkatesh,Chandrama Prakash Upadhyaya,Akula Nookaraju,Shashank K. Pandey,Se Won Park +5 more
TL;DR: This review summarizes the recent applications and future potential of R-genes in crop disease management and indicates that with the onset of recent genomic, bioinformatics and molecular biology techniques, it is quite possible to tame the R- Genes for efficiently controlling the plant diseases caused by pathogens.
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