title: Analysis of the role of transcription factor VAD-5 in conidiation of Neurospora crassa.
abstract: Conidiation is the major mode of reproduction in many filamentous fungi. The Neurospora crassa gene vad-5, which encodes a GAL4-like Zn2Cys6 transcription factor, was suggested to contribute to conidiation in a previous study using a knockout mutant. In this study, we confirmed the positive contribution of vad-5 to conidiation by gene complementation. To understand the role of vad-5 in conidiation, transcriptomic profiles generated by digital gene expression profiling from the vad-5 deletion mutant and the wild-type strain were compared. Among 7559 detected genes, 176 genes were found to be transcriptionally down-regulated and 277 genes transcriptionally upregulated in the vad-5 deletion mutant, using ≥1-fold change as a cutoff threshold. Among the down-regulated genes, four which were already known to be involved in conidiation -fluffy, ada-6, rca-1, and eas - were examined further in a time course experiment. Transcription of each of the four genes in the vad-5 deletion mutant was lower than in the wild-type strain during conidial development. Phenotypic observation of deletion mutants for 132 genes down-regulated by vad-5 deletion revealed that deletion mutants for 17 genes, including fluffy, ada-6, and eas, produced fewer conidia than the wild type. By phenotypic observation of deletion mutants for 211 genes upregulated in the vad-5 deletion mutant, two types of deletion mutants were found. One type, which produced more conidia than the wild-type strain, includes deletion mutants for previously characterized genes cat-2, cat-3, and sah-1 and for a non-characterized gene NCU07221. Deletion mutants of NCU06302 and NCU11090, representing the second type, produced conidia earlier than the wild-type strain. Based on these conidiation phenotypes, we designated NCU07221 as high conidial production-1 (hcp-1) and named NCU06302 and NCU11090 as early conidial development-1 (ecd-1) and ecd-2, respectively. Given the collective results from this study, we propose that vad-5 exerts an effect on conidiation by activating genes that positively contribute to conidiation as well as by repressing genes that negatively influence conidial development.
authors.affiliation: State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Xianyun
authors.initials: X
authors.lastname: Sun
authors.forename: Luning
authors.initials: L
authors.lastname: Yu
authors.forename: Nan
authors.initials: N
authors.lastname: Lan
authors.forename: Shiping
authors.initials: S
authors.lastname: Wei
authors.forename: Yufei
authors.initials: Y
authors.lastname: Yu
authors.forename: Hanxing
authors.initials: H
authors.lastname: Zhang
authors.forename: Xinyu
authors.initials: X
authors.lastname: Zhang
authors.forename: Shaojie
authors.initials: S
authors.lastname: Li
mesh_terms: D017353:Gene Deletion; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development*; D013172:Spores, Fungal / Q000235:genetics* / Q000254:growth & development*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D014157:Transcription Factors