genetics of Neurospora

Genetics of Neurospora:

It is the Neurospora with which much of fundamental research on eukaryotic molecular biology and biochemical genetics has been carried out and is now genetically one of the most intensively studied organisms.

By studying the biosynthesis of amino acids, vitamins and other substances by the Neurospora crassa, Shear and Dodge in 1930 pointed out the following properties of N. crassa that make it an ideal experimental organisms for knowing the action of genes in the inheritance of characters and the way in which genes can cooperate chemically to bring about their effects in biochemical path ways. 

1. Fungus has simple nutritional requirements, a carbohydrate source, simple mineral salts, and one vitamin biotin;
2. exists in the haploid state for the most of its life cycle;
3. it has very few chromosome which can be easily viewed under the microscope;
4. mutation can be induced by irradiation;
5. it is a fast growing fungus that multiplies profusely by conidia, therefore any strain can undergo million fold multiplication in a few days without any genetic change;
6. Sexual reproduction can be completed within a matter of ten days and consequently a number of generations can be easily obtained within much shorter time for tracing the inheritable characteristics;
7. its genes can be changed artificially and the role they play in the chemical alteration and metabolism of cells can be determined precisely;
8. analysis of ordered tetrads is very easy by means of ascus dissection;
9. it is possible to identify and follow the fate of each of four chromatids present in the bivalent meotic chromosome and thus to determine whether the crossing over involves two, three or all four chromatids; and 
10. it is possible to co-relate the genetic constitution and biochemical expression of genes.

Geneticists and biochemists alerted by Dodge's discoveries began using Neurospora as an experimental tool.  A series of researches followed that brought out the manner in which genes control enzymes and elucidated the biochemical pathways that operate in living organisms. In 1940, N. crassa was chosen by Beadle and Tatum to examine the possibility that genes control the production of enzymes. 

In 1941, Beadle and Tatum demonstrated that it is possible to isolate biochemical mutants from the N. crassa. This opened the way to the analysis of the consequences of mutation on biochemical terms and Neurospora joined the Drosophila and the maize plant as a material of choice for genetic research. Some mutant cultures obtained in this way were shown to have nutrient requirements which the parental strain can synthesize de novo, and it was established that such a deficiency could result from formatting of enzymes. The early studies with the biochemical mutants  led to the hypothesis that each individual enzyme is encoded by a single gene, which became known as one-gene-one-enzyme hypothesis. In 1958, Beadle and Tatum were awarded Noble Prize for the work.

Neurospora crassa, thus laid the foundation of a new branch of science that has come to be known as naploid genetic(Biochemical genetics).