APS Homepage

Poster: Molecular & Cellular Plant-Microbe Interactions: Proteomics/Metabolomics/Genomics


Independent amplification of a housekeeping gene and its evolutionary significance in the Dothideomycetes
B. DHILLON (1), G. Kema (2), S. Goodwin (3), B. Bluhm (1) (1) University of Arkansas, U.S.A.; (2) Plant Research International, Wageningen University and Research Centre, Netherlands; (3) USDA/ARS Purdue University, U.S.A.

Transposable elements (TEs) are key drivers of genome evolution, but the exact mechanisms of how they modulate gene and genome function are largely unknown. We identified an event where a housekeeping gene (histone H3) was captured and amplified by a hAT DNA transposon in the genome of the banana pathogen Pseudocercospora fijiensis. Comparative genome analysis in related Capnodiales revealed a similar event occurred in the corn pathogens Cercospora zeae-maydis and C. zeina, but was lacking in the soybean pathogens C. sojina and C. flagellaris. Histone H3 amplification had been described previously in Pleosporales (Pyrenophora tritici-repentis). Our analysis showed key differences in the amplification events between the Pleosporales and Capnodiales, namely, 1) extent of histone H3 amplification, 2) difference in H3 nucleotide composition and 3) number of functional H3 genes present. In the Capnodiales, all amplified H3 copies were inactivated by RIP, which suggests the original H3 gene was under strong negative selection pressure. The interplay of TEs and RIP can result in various outcomes for gene and genome evolution. For instance, when TEs act as breeding grounds for pathogenicity genes, such interactions can influence gene function and/or regulation, and ultimately affect host-pathogen interactions.