Preliminary Study About The Influence Of Stress Environment To Fungus On Sexual Reproduction

The maintenance and evolution of sexual reproduction is a focus in evolutionary biology. Although sexual reproduction maybe destroy combination of dominant genes and consume too much time and energy expenditure, the most facultatively sexual organisms will choose to sexual reproduction. The hypothesis, the stress environment maybe promote the fungus to sexual reproduction, is approved by some people. Experimental evolution of several model organisms provided evidences for relationship between the evolution of sex and heterogeneity environments, which was questioned because of limited timescales and the simplified nature of laboratory environments.Nematode-trapping fungi (A. musiformis) are facultatively sexual organisms. The anamorph of A. musiformis is belongs to the Arthrobotrys, and the teleomorph is one of anamorph of Orbilia spp. The species are widely distributed, not only the general environment, but also in various environments.In this study, the effectect of natural stress environment on the sexual reproduction of fungi was studied, and we used three different sources groups of the species. Three groups are:one group was from ascospores separation by sexual reproducetion (sex); one group was from soil by spore separation which is asexual reproduction (XS); one group was from the sediment of Dianchi Lake which was divided by asexual reproduction (DC).1. The ITS and4sexual reproductive related genes (ran1, ndk-1, sexM, cpc-2) of the three populations were constructed NJ by the Mega software. The results turned out that the strains from Dianchi and from ascospore isolation at the population level showed a closer relationship, while the strains from Dianchi and from farmland soil near Dianchi are relatively far. Preliminary inference that the environment of the Dianchi promoted the evolution of sexual reproduction..2. Based on the gene linkage analysis and reorganization of the Dianchi environmental strains, PTLPT RbarD and the corresponding P values were greater than0.001. The result showed that the Dianchi environmental strain was random genetic recombination, and the strains in the Dianchi sediment environment had occurred sexual reproduction.3. The analysis of Single Nucleotide Polymorphisms (SNPs) of four sexual reproduction related genes showed that the mutation sites of the ascospore strains and the strain from Dianchi were mainly consistent. It was further explained that the Dianchi may promote the fungi to sexual reproduction in the sexual direction.4. The suitability of the strains for three populations was tested by simulating several stress environments. The strains of DC and sex were significantly better than that of the XS group in the resistance to Cd and Pb, high temperature and pH. Also the difference was significant. The fittness of the DC group to other stress environment is also high.This showed that the evolution of the Dianchi was related to the evolution of sexual reproduction.