General intro

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Required

3 studies- continued

Seems to be associated with meiosis

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Complex nature of R-gene loci leads to their unstable nature.

BENNETZEN, J. L., W. E. BLEVINS and A. H. ELLINGBOE, 1988 Cell-Autonomous Recognition of the Rust Pathogen Determines Rp1-Specified Resistance in Maize. Science 241: 208-210.

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Many R and AVR genes have been cloned

Cloning of First Avr Genes

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Avr9 was cloned by purifying and sequencing the protein and using this info to get to the gene.

What happens if you express Avr9 transgenically in a Cf9 plant?

Ac is a DNA transposon- “Jumping gene”

Cloning an R-gene

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It’s disastrous to let them fall into the “wrong hands”

And why does the pathogen have them??

Hypersenesitive reaction and pathogenicity.

What’s going on?

Many are components of the bacterial Type III secretion system, which can inject proteins into host cells.

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Often act as virulence or effector proteins in the absence of corresponding R-gene

Can be defined a number of ways;

All (?) Avr genes are effectors

We now know that microbial pathogens export a whole arsenal of effector molecules into their host to alter their environment for their purposes.

Hogenhout et al MPMI 2009 22:115-122 list the following functions: