RESUMO
Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.
Assuntos
Ascomicetos/genética , Deleção de Genes , Genes Fúngicos , Genoma Fúngico , Hordeum/microbiologia , Doenças das Plantas/microbiologia , Adaptação Fisiológica , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/metabolismo , Ascomicetos/patogenicidade , Metabolismo dos Carboidratos , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Enzimas/genética , Enzimas/metabolismo , Evolução Molecular , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Interações Hospedeiro-Patógeno/genética , Redes e Vias Metabólicas/genética , Anotação de Sequência Molecular , Retroelementos , Análise de Sequência de DNA , Especificidade da EspécieRESUMO
Retrotransposons are retrovirus-related mobile sequences that have the potential to replicate via RNA intermediates and increase the genome size by insertion into new sites. The retroelement, Gret1, has been identified as playing a key role in generating fruit color variation in cultivated grape (Vitis vinifera L.) due to its insertion into the promoter of VvMybA1. Fruit color variation is an important distinguishing feature of cultivated grapes and virtually no fruit color variation is observed in wild grape species. The presence and relative copy number of Gret1 was assessed using quantitative PCR on 22 different Vitis species, only four of which (plus interspecific hybrids) are known to contain white accessions. Gret1 copy number was observed to vary by species as well as by color within species and was significantly higher in white-fruited accessions across all taxa tested. Additionally, genomic regions surrounding Gret1 insertion were sequenced in white V. vinifera, hybrid, V. labrusca, V. aestivalis, and V. riparia accessions.
