title: Fruiting Body Formation in Volvariella volvacea Can Occur Independently of Its MAT-A-Controlled Bipolar Mating System, Enabling Homothallic and Heterothallic Life Cycles.
abstract: Volvariella volvacea is an important crop in Southeast Asia, but erratic fruiting presents a serious challenge for its production and breeding. Efforts to explain inconsistent fruiting have been complicated by the multinucleate nature, typical lack of clamp connections, and an incompletely identified sexual reproductive system. In this study, we addressed the life cycle of V. volvacea using whole genome sequencing, cloning of MAT loci, karyotyping of spores, and fruiting assays. Microscopy analysis of spores had previously indicated the possible coexistence of heterothallic and homothallic life cycles. Our analysis of the MAT loci showed that only MAT-A, and not MAT-B, controlled heterokaryotization. Thus, the heterothallic life cycle was bipolar. Karyotyping of single spore isolates (SSIs) using molecular markers supported the existence of heterokaryotic spores. However, most SSIs were clearly not heterokaryotic, yet contained structural variation (SV) markers relating to both alleles of both parents. Heterokaryons from crossed, self-sterile homokaryons could produce fruiting bodies, agreeing with bipolar heterothallism. Meanwhile, some SSIs with two different MAT-A loci also produced fruiting bodies, which supported secondary homothallism. Next, SSIs that clearly contained only one MAT-A locus (homothallism) were also able to fruit, demonstrating that self-fertile SSIs were not, per definition, secondary homothallic, and that a third life cycle or genetic mechanism must exist. Finally, recombination between SV markers was normal, yet 10 out of 24 SV markers showed 1:2 or 1:3 distributions in the spores, and large numbers of SSIs contained doubled SV markers. This indicated selfish genes, and possibly partial aneuploidy.
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Bingzhi
authors.identifier: 0000-0003-0254-7475
authors.initials: B
authors.lastname: Chen
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Arend F
authors.initials: AF
authors.lastname: van Peer
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Yan
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Bin
authors.identifier: 0000-0003-2192-4168
authors.initials: B
authors.lastname: Xie
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Miao
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Qianhui
authors.initials: Q
authors.lastname: Huang
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Junsheng
authors.initials: J
authors.lastname: Fu
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Fengli
authors.initials: F
authors.lastname: Hu
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Qingfang
authors.initials: Q
authors.lastname: Kong
authors.affiliation: Institute of Microbiology, State Key Laboratory of Mycology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Xianyun
authors.initials: X
authors.lastname: Sun
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zou
authors.affiliation: Institute of Microbiology, State Key Laboratory of Mycology, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Hanxing
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Microbiology, State Key Laboratory of Mycology, Chinese Academy of Sciences, Beijing 100080, China Lisj@im.ac.cn mrcfafu@163.com.
authors.forename: Shaojie
authors.initials: S
authors.lastname: Li
authors.affiliation: Mycological Research Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China Lisj@im.ac.cn mrcfafu@163.com.
authors.forename: Baogui
authors.initials: B
authors.lastname: Xie
mesh_terms: D000595:Amino Acid Sequence; D000782:Aneuploidy; D001947:Breeding; D002874:Chromosome Mapping; D048690:Fruiting Bodies, Fungal / Q000235:genetics* / Q000254:growth & development; D049770:Genes, Mating Type, Fungal; D056426:Genetic Loci; D005819:Genetic Markers; D014644:Genetic Variation; D016681:Genome, Fungal; D007621:Karyotyping; D010802:Phylogeny; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000235:genetics* / Q000254:growth & development; D055367:Volvariella / Q000145:classification / Q000235:genetics* / Q000254:growth & development
chemical_list: D005819:Genetic Markers
keywords: Volvariella volvacea; amphithallic; aneuploidy; genomic analysis; mating-type system