High throughput mating tests in Neurospora crassa

Mating type tests in Neurospora crassa are an important way to characterize strains. Since most of the knock-out mutants developed as part of the functional genomics program (Colot et al., 2006) have little obvious phenotype we have undertaken to test the mating type of all of the knock-strains that are sent to the FGSC. Our original mating type test protocol is similar to that described by Smith (1962) and involves growing a lawn of the fluffy tester strains (4317 or 4347) on cornmeal agar (Difco) in 15 cm petri plates. This is also described in the online Neurospora protocol, "How to use fluffy testers for determining mating type and for other applications" (http://www.fgsc.net/Neurospora/NeurosporaProtocolGuide.htm). The strains to be tested are grown on Vogels minimal (Vogel, 1956) or appropriately supplemented medium (McCluskey, 2003) and small amounts of conidia are transferred to a spot on a grid. Using this technique, thirty to forty strains can be tested on two plates. While robust, this technique is labor intensive and because the plate is opened for each inoculation there is the possibility that occasional stray conidia could confound the results.