Question 1

Why is a failed cross difficult to interpret?

Accepted Answer

Because incompatibility and unmet conditions produce the same observation. Many species mate only under specific light, medium or temperature regimes, and a single attempt under standard conditions tests very little. Vary conditions systematically and report the range tried, so that a negative result carries the weight it deserves and no more.

Question 2

Why does similarity searching fail for mating-type loci?

Accepted Answer

Because the sequences are idiomorphs rather than alleles: they occupy the same position but are unrelated to each other, so a query built from one mating type will not retrieve the other. Identification proceeds instead through synteny, locating the conserved flanking genes and examining whatever lies between them.

Question 3

Can mating type be assigned from sequence alone?

Accepted Answer

It can be proposed, not established. A sequence resembling a known regulator or receptor suggests a role, but function in this system depends on specific pairings that similarity does not predict. Treat sequence-based assignment as a hypothesis and report it as such until a functional test supports it.

Question 4

What extra burden does a tetrapolar system impose?

Accepted Answer

Two independently segregating loci must be tracked in every progeny individual, which doubles the genotyping work and raises the number of progeny needed. Small sets cannot distinguish independent segregation from linkage, so decide the progeny number from the segregation pattern being tested rather than from convenience.

Question 5

How should homothallic species be handled?

Accepted Answer

With care about what selfing implies, since a species that can self may still outcross, and observing self-fertility does not establish that outcrossing never happens. Where the question concerns population structure, selfing capacity and actual mating behaviour in the field are separate matters requiring separate evidence.

Question 6

Do pheromone and receptor pairings need testing individually?

Accepted Answer

Yes, since specificity is the point of the system and predicted pairings frequently prove wrong. Functional assays that pair a candidate pheromone with a candidate receptor, rather than inference from sequence groupings, are what support a claim about which mating types can recognise one another.

Question 7

How much does strain history matter?

Accepted Answer

Considerably, because laboratory strains lose mating competence over successive transfers and a strain that once crossed may no longer do so. Record passage history, store material at low passage, and re-verify mating competence periodically rather than assuming a strain retains the behaviour originally described.

Microbiology

Microbiology

Research Frontiers in Fungal Mating-Type Loci and Sexual Reproduction Control