Tiêu đề 05 Para-sexuality in fungi.pdf ✅

➢ Until 1944, the sexual cycle was the only means of exchange of genetic material. ➢ A similar alternative to sexual reproduction, parasexuality was first discovered in 1952 by Pontecorvo and Roper of the University of Glasgow in Aspergillus nidulans, the imperfect state of Emericella nidulans ➢ The parasexual cycle was defined as plasmogamy, karyogamy and mitosis (Haploidization) occurs but of different type and on different time in the life cycle of an organism. ➢ In Deuteromycetes, lacking a sexual cycle and they typically undergo a parasexual cycle. ➢ These cycle has been discovered not only in Deuteromycetes but also in fungi belonging to Ascomycetes and Basidiomycetes.


➢ The genotype of different nuclei present in the heterokaryotic mycelium is A and B, then five types of nuclei can be formed by their fusion: I. No fusion of A nuclei, results in A haploid nuclei. II. No fusion of B nuclei, results in B haploid nuclei. III. Fusion of two A nuclei (A + A = AA), results in homozygous diploid nuclei. IV. Fusion of two A nuclei (B + B = BB), results in homozygous diploid nuclei. V. Fusion of A and B nuclei (A + B = AB), results in heterozygous diploid nuclei. Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Anastomasis Strain 1 Strain 2 Heterokaryotic mycelium Heterozygous diploid nuclei Mitotic crossing over Sorting out of diploid nuclei Diploid mycelia Occasional haploidisation of diploid nuclei Sorting of new haploid strains Formation of new gene combination