Organization of chromosome ends in the rice blast fungus, Magnaporthe oryzae

Cathryn Rehmeyer, Weixi Li, Motoaki Kusaba, Yun Sik Kim, Doug Brown, Chuck Staben, Ralph Dean, Mark Farman

Research output: Contribution to journalArticlepeer-review

82 Scopus citations

Abstract

Eukaryotic pathogens of humans often evade the immune system by switching the expression of surface proteins encoded by subtelomeric gene families. To determine if plant pathogenic fungi use a similar mechanism to avoid host defenses, we sequenced the 14 chromosome ends of the rice blast pathogen, Magnaporthe oryzae. One telomere is directly joined to ribosomal RNA-encoding genes, at the end of the ∼2 Mb rDNA array. Two are attached to chromosome-unique sequences, and the remainder adjoin a distinct subtelomere region, consisting of a telomere-linked RecQ-helicase (TLH) gene flanked by several blocks of tandem repeats. Unlike other microbes, M.oryzae exhibits very little gene amplification in the subtelomere regions-out of 261 predicted genes found within 100 kb of the telomeres, only four were present at more than one chromosome end. Therefore, it seems unlikely that M.oryzae uses switching mechanisms to evade host defenses. Instead, the M.oryzae telomeres have undergone frequent terminal truncation, and there is evidence of extensive ectopic recombination among transposons in these regions. We propose that the M.oryzae chromosome termini play more subtle roles in host adaptation by promoting the loss of terminally-positioned genes that tend to trigger host defenses.

Original languageEnglish
Pages (from-to)4685-4701
Number of pages17
JournalNucleic Acids Research
Volume34
Issue number17
DOIs
StatePublished - Oct 2006

ASJC Scopus subject areas

  • Genetics

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