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Comparative Analysis of Phytophthora Genes Encoding Secreted Proteins Reveals Conserved Synteny and Lineage-Specific Gene Duplications and Deletions

December 2006 , Volume 19 , Number  12
Pages  1,311 - 1,321

Rays H. Y. Jiang , 1 Brett M. Tyler , 1 , 2 and Francine Govers 1

1Laboratory of Phytopathology, Plant Sciences Group, Wageningen University, Binnenhaven 5, NL-6709 PD Wageningen and Graduate School Experimental Plant Sciences, The Netherlands; 2Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg 24061, U.S.A.

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Accepted 31 July 2006.

Comparative analysis of two Phytophthora genomes revealed overall colinearity in four genomic regions consisting of a 1.5-Mb sequence of Phytophthora sojae and a 0.9-Mb sequence of P. ramorum. In these regions with conserved synteny, the gene order is largely similar; however, genome rearrangements also have occurred. Deletions and duplications often were found in association with genes encoding secreted proteins, including effectors that are important for interaction with host plants. Among secreted protein genes, different evolutionary patterns were found. Elicitin genes that code for a complex family of highly conserved Phytophthora-specific elicitors show conservation in gene number and order, and often are clustered. In contrast, the race-specific elicitor gene Avr1b-1 appeared to be missing from the region with conserved synteny, as were its five homologs that are scattered over the four genomic regions. Some gene families encoding secreted proteins were found to be expanded in one species compared with the other. This could be the result of either repeated gene duplications in one species or specific deletions in the other. These different evolutionary patterns may shed light on the functions of these secreted proteins in the biology and pathology of the two Phytophthora spp.

Additional keywords: comparative genomics , RXLR-dEER .

© 2006 The American Phytopathological Society