Answer:
+ and -
Explanation:
Sexual reproduction occurs when the hyphae of two different strains meet and merge. For this to happen the two strains must be compatible, they are designated as + and -.
When these are found, two cells are formed in the apical region that are called gametangios, one of them contains + nuclei and the other -, when fused they will form diploid nuclei that will produce the zygote.
