| Schizophyllum commune is a basidiomycete that reproduce sexually through heterologous mating.It is a species belonging to Basidiomycotina,Agaricales,Schizophyllaceae and Schizophyllum.As one of the most widely distributed fungi on the earth,S.commune could colonize at least 150 genera of woody plants.S.commune has complex polysaccharide decomposition machines and biological activities,which has been widely used in environmental management,industrial production,medical and health fields.In addition,S.commune can also cause diseases such as epidural abscess,skin infectious granuloma,bacterial sinusitis and allergic bronchopulmonary mycosis.As we all know,S.commune is also a model mushroom,which has been sequenced and used in the study of cell wall formation,hyphal fusion and development,and mating types of fungi.With typical bifactorial quadrupole mating system,S.commune is an ideal species for the study of the genetic evolution of fungi and other organisms.In this study,we focus on the genetic and biological characteristics of the(sub-)mating type of a S.commune strain 20R-7-F01,which was isolated from coal-bearing sediments about 2 km depth below the ocean floor formore than 20 million years ago.From the point of view of sexual reproduction genetic variation,the phylogenetic evolution of this fungsi was studied in terms of the genetic variation of sexual reproduction.The results showed in followings:1.A total of the 3×10~7basidiospores were collected from S.commune20R-7-F01 using basidiospore collection method.Among the basidiospores,a total of24 monokarytes were identified by microscopic examination on the occurrence of clamp connexion,and observation of fruiting body formation,which excluded the existence of binucleate mycelia.Based on morphology observation of the colony and hyphae,the 24 monokarytes showed different growth phenotypes on PDA plates,which could be summarized as four types:flat,villous,basal and loose.2.A total of four mating types,namely AxBx,AxBy,AyBx and AyBy,accounting for 20%,40%,15%and 25%respectively,were identified from 20monokaryons of S.commune 20R-7-F01 by means of confrontation reaction,fruiting body formation observation,and PCR amplification of mating genes.Fisher's test showed that there was no significant difference in the proportion of different mating types,indicating that there was no segregation of mating genes.3.Compared with the mating genes of modern S.commune strain H4-8,the number of monokaryon mating genes of S.commune 20R-7-F01 was relatively small.Mating site A contains HD2 family genes aay1 and abr6,while the mating site B contains bbr2,bar3,bbp2(1)and bbp2(2)genes,as well as one gene encoding pheromone-like and one gene encoding pheromone-like pheromone receptors.The mating genes are highly conserved in S.commune,but vary greatly in amino acid sequence.4.The effects of different media,carbon source,nitrogen source,heavy metals and pH on the growth rate of the(sub-)mating types of S.commune 20R-7-F01 were performed.The result showed that the mating type of AyBx has a strong environmental adaptability.In summary,the mating genetic composition of S.commune 20R-7-F01 is relatively simple,providing the fungus with the ability to adapt to the subseafloor environment by reducing unnecessary waste of material and energy while maintaining the ability to complete sexual cycle. |
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