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Home • Neurospora crassa FGSC4200 ORS-SL6a (aka "ORS6a") v3.0
 4:4 segregation of spores for the GFP phenotype
Cross of a matA hH1-gfp strain to a mata strain reveals 4:4 segregation of spores for the GFP phenotype because the mating type locus mat and the H1-GFP gene inserted at the his-3 locus are both linked to the centromere or chromosome 1. (Ref. 3). Image Credit: Michael Freitag

Neurospora crassa is a filamentous fungus, i.e. growing as hyphae rather than forming unicellular yeast cells. Filamentous fungi are important in natural environments as degraders of plant and animal biomass, as pathogens of plants and animals, and as producers of natural products that are used as pharmaceuticals. The genus Neurospora holds a central position in the history of genetics, biochemistry, and molecular biology, as one of the earliest convenient model organisms that helped to decipher the gene to protein relationships of metabolism and gene regulation. Ongoing studies on light regulation, the circadian clock, chromatin and epigenetics, gene regulation, and metabolism continue to yield insights into general eukaryotic biology.

Neurospora crassa strain FGSC4200, often abbreviated “ORS6a” is closely related to the reference strain OR74A. Strain 74-ORS-6a was obtained by six backcrosses to 74-OR23-1VA (1). FGSC2489 and FGSC4200 are the best matched, near-isogenic reference strains of opposing mating types, matA and mata, respectively. The current version of the genome is almost complete, for all seven chromosomes from telomere to telomere. No earlier version of the FGSC4200 genome is available but the updated reference genome of FGSC 2489 74-OR23-1VA (aka “74A”) is available here. A first high-quality draft of the FGSC2489 genome was sequenced at the Broad institute of MIT and released in 2003 (2), and it is still available at https://mycocosm.jgi.doe.gov/Neucr2.


  1. Käfer E. Backcrossed mutant strains which produce consistent map distances and little interference. Neurospora Newsl. 1982  29:41-44.
  2. Galagan JE, Calvo SE, Borkovich KA, Selker EU, Read ND, Jaffe D, FitzHugh W, Ma LJ, Smirnov S, Purcell S, Rehman B, Elkins T, Engels R, Wang S, Nielsen CB, Butler J, Endrizzi M, Qui D, Ianakiev P, Bell-Pedersen D, Nelson MA, Werner-Washburne M, Selitrennikoff CP, Kinsey JA, Braun EL, Zelter A, Schulte U, Kothe GO, Jedd G, Mewes W, Staben C, Marcotte E, Greenberg D, Roy A, Foley K, Naylor J, Stange-Thomann N, Barrett R, Gnerre S, Kamal M, Kamvysselis M, Mauceli E, Bielke C, Rudd S, Frishman D, Krystofova S, Rasmussen C, Metzenberg RL, Perkins DD, Kroken S, Cogoni C, Macino G, Catcheside D, Li W, Pratt RJ, Osmani SA, DeSouza CP, Glass L, Orbach MJ, Berglund JA, Voelker R, Yarden O, Plamann M, Seiler S, Dunlap J, Radford A, Aramayo R, Natvig DO, Alex LA, Mannhaupt G, Ebbole DJ, Freitag M, Paulsen I, Sachs MS, Lander ES, Nusbaum C, Birren B. The genome sequence of the filamentous fungus Neurospora crassa. Nature. 2003 Apr 24;422(6934):859-68. doi: 10.1038/nature01554.
  3. Freitag M, Hickey PC, Raju NB, Selker EU, Read ND. GFP as a tool to analyze the organization, dynamics and function of nuclei and microtubules in Neurospora crassa. Fungal Genet Biol. 2004 Oct;41(10):897-910. doi: 10.1016/j.fgb.2004.06.008.