AoRim15 is involved in conidial stress tolerance, conidiation and sclerotia formation in the filamentous fungus Aspergillus oryzae
Section snippets
Strains, media and transformation
The strains used in this study are listed in Table 1. A. oryzae wild-type strain RIB40 (30) and strain NSPlD1, which has a highly efficient gene-targeting background (niaD- sC- ΔpyrG ΔligD) (31), were used as a DNA donor and transformation host, respectively. M + Met medium (0.2% NH4Cl, 0.1% (NH4)2SO4, 0.05% KCl, 0.05% NaCl, 0.1% KH2PO4, 0.05% MgSO4·7H2O, 0.002% FeSO4·7H2O, 2% glucose, and 0.15% methionine, pH 5.5) was used as a selective medium for deleting the Aorim15 gene. CD + Met medium
Deletion and overexpression of the Aorim15 gene in A. oryzae
We searched for gene(s) homologous to S. cerevisiae RIM15 in the A. oryzae genome database (http://www.bio.nite.go.jp/dogan/project/view/AO) using the BLAST algorithm and found AO090012000420, which was named Aorim15. Based on rapid amplification of 5′ and 3′ cDNA ends (5′ and 3′ RACE) analysis (data not shown), it was concluded that the identified Aorim15 gene contains two exons and one intron, encoding a polypeptide of 2055 amino acids, which shares 21% identity with S. cerevisiae Rim15p (
Discussion
S. cerevisiae Rim15p functions as a central regulator of stress signaling and is required for stress tolerance; however, the physiological functions of the corresponding proteins have been poorly characterized in filamentous fungi. In the present study, by deleting and overexpressing the Aorim15 gene in A. oryzae, we clearly demonstrated that AoRim15 is involved in conidial stress tolerance, conidiation, and sclerotia formation.
Genomic deletion of Aorim15 significantly reduced the number of
Acknowledgments
This work was supported by a Grant-in-Aid for Young Scientists from the Japan Society for the Promotion of Science (grant 25712007). Funding for this study was also provided by Research and Development Projects for Application in Promoting New Policy of Agriculture, Forestry and Fisheries from National Agriculture and Food Research Organization, Japan (grant 25027A), and by the Institute for Fermentation, Osaka (IFO), Japan.
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Present address: College of Biology and the Environment, Nanjing Forestry University, 159 Longpan Road, Nanjing 210037, China.