The gene for a lectin-like protein is transcriptionally activated during sexual development, but is not essential for fruiting body formation in the filamentous fungus Sordaria macrospora

Minou Nowrousian,Patricia Cebula

doi:10.1186/1471-2180-5-64

Minou Nowrousian, Patricia Cebula

Open Access

https://doi.org/10.1186/1471-2180-5-64

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Journal: BMC microbiology	Publication Date: Nov 3, 2005
Citations: 89	License type: cc-by

Affiliation: Ruhr University Bochum

Abstract

BackgroundThe filamentous fungus Sordaria macrospora forms complex three-dimensional fruiting bodies called perithecia that protect the developing ascospores and ensure their proper discharge. In previous microarray analyses, several genes have been identified that are downregulated in sterile mutants compared to the wild type. Among these genes was tap1 (transcript associated with perithecial development), a gene encoding a putative lectin homolog.ResultsAnalysis of tap1 transcript levels in the wild type under conditions allowing only vegetative growth compared to conditions that lead to fruiting body development showed that tap1 is not only downregulated in developmental mutants but is also upregulated in the wild type during fruiting body development. We have cloned and sequenced a 3.2 kb fragment of genomic DNA containing the tap1 open reading frame and adjoining sequences. The genomic region comprising tap1 is syntenic to its homologous region in the closely related filamentous fungus Neurospora crassa. To determine whether tap1 is involved in fruiting body development in S. macrospora, a knockout construct was generated in which the tap1 open reading frame was replaced by the hygromycin B resistance gene hph under the control of fungal regulatory regions. Transformation of the S. macrospora wild type with this construct resulted in a tap1 deletion strain where tap1 had been replaced by the hph cassette. The knockout strain displayed no phenotypic differences under conditions of vegetative growth and sexual development when compared to the wild type. Double mutants carrying the Δtap1 allele in several developmental mutant backgrounds were phenotypically similar to the corresponding developmental mutant strains.ConclusionThe tap1 transcript is strongly upregulated during sexual development in S. macrospora; however, analysis of a tap1 knockout strain shows that tap1 is not essential for fruiting body formation in S. macrospora.

Highlights

The filamentous fungus Sordaria macrospora forms complex three-dimensional fruiting bodies called perithecia that protect the developing ascospores and ensure their proper discharge
Expression of tap1 during sexual development in S. macrospora Previously, we reported that tap1 is downregulated in several developmental mutants when compared with the wild type [3]
To investigate whether tap1 expression in the wild type is associated with sexual development, we compared transcript levels of tap1 in sexually developing mycelia with vegetative mycelia

Summary

Introduction

The filamentous fungus Sordaria macrospora forms complex three-dimensional fruiting bodies called perithecia that protect the developing ascospores and ensure their proper discharge. Several genes have been identified that are downregulated in sterile mutants compared to the wild type. Among these genes was tap (transcript associated with perithecial development), a gene encoding a putative lectin homolog. Fruiting body formation in ascomycetes is a complex process leading to the formation of a number of specialized cell types from a comparatively undifferentiated vegetative mycelium [1]. Tap transcript levels in the wild type under conditions of vegetative and sexual development were analyzed by real time PCR. Expression is given as fold induction (mean of two independent experiments, error bars indicate standard deviation) with transcript levels during vegetative growth set to 1. A coherent picture of fungal multicellular development has yet to emerge [2]

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