title: Analysis of in planta Expressed Orphan Genes in the Rice Blast Fungus Magnaporthe oryzae.
abstract: Genomes contain a large number of unique genes which have not been found in other species. Although the origin of such "orphan" genes remains unclear, they are thought to be involved in species-specific adaptive processes. Here, we analyzed seven orphan genes (MoSPC1 to MoSPC7) prioritized based on in planta expressed sequence tag data in the rice blast fungus, Magnaporthe oryzae. Expression analysis using qRT-PCR confirmed the expression of four genes (MoSPC1, MoSPC2, MoSPC3 and MoSPC7) during plant infection. However, individual deletion mutants of these four genes did not differ from the wild-type strain for all phenotypes examined, including pathogenicity. The length, GC contents, codon adaptation index and expression during mycelial growth of the four genes suggest that these genes formed during the evolutionary history of M. oryzae. Synteny analyses using closely related fungal species corroborated the notion that these genes evolved de novo in the M. oryzae genome. In this report, we discuss our inability to detect phenotypic changes in the four deletion mutants. Based on these results, the four orphan genes may be products of de novo gene birth processes, and their adaptive potential is in the course of being tested for retention or extinction through natural selection.
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Abu
authors.initials: A
authors.lastname: Sadat
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Junhyun
authors.initials: J
authors.lastname: Jeon
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Albely Afifa
authors.initials: AA
authors.lastname: Mir
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Seongbeom
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Jaeyoung
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Agricultural Biotechnology, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea ; Center for Fungal Pathogenesis, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea ; Center for Fungal Genetic Resources, Plant Genomics and Breeding Institute, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea.
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Lee
keywords: Magnaporthe oryzae; fungal pathogenesis; gene birth; orphan gene