TY  - JOUR
A1  - Jiang, Rays H.Y.
A1  - Weide, Rob
A1  - van de Vondervoort, Peter J.I.
A1  - Govers, Francine
T1  - Amplification generates modular diversity at an avirulence locus in the pathogen Phytophthora
Y1  - 2006/07/01 
JF  - Genome Research 
JO  - Genome Research 
SP  - 827 
EP  - 840 
DO  - 10.1101/gr.5193806 
VL  - 16 
IS  - 7 
UR  - http://genome.cshlp.org/content/16/7/827.abstract 
N2  - The destructive late blight pathogen Phytophthora infestans is notorious for its rapid adaptation to circumvent detection mediated by plant resistance (R) genes. We performed comparative genomic hybridization on microarrays (array-CGH) in a near genome-wide survey to identify genome rearrangements related to changes in virulence. Six loci with copy number variation were found, one of which involves an amplification colocalizing with a previously identified locus that confers avirulence in combination with either R gene R3b, R10, or R11. Besides array-CGH, we used three independent approaches to find candidate genes at the Avr3b–Avr10–Avr11 locus: positional cloning, cDNA-AFLP analysis, and Affymetrix array expression profiling. This resulted in one candidate, pi3.4, that encodes a protein of 1956 amino acids with regulatory domains characteristic for transcription factors. Amplification is restricted to the 3′ end of the full-length gene but the amplified copies still contain the hallmarks of a regulatory protein. Sequence comparison showed that the amplification may generate modular diversity and assist in the assembly of novel full-length genes via unequal crossing-over. Analyses of P. infestans field isolates revealed that the pi3.4 amplification correlates with avirulence; isolates virulent on R3b, R10, and R11 plants lack the amplified gene cluster. The ancestral state of 3.4 in the Phytophthora lineage is a full-length, single-copy gene. In P. infestans, however, pi3.4 is a dynamic gene that is amplified and has moved to other locations. Modular diversity could be a novel mechanism for pathogens to quickly adapt to changes in the environment. 
ER  -