菌根真菌对酸铝胁迫的响应

酸性环境中活性铝浓度升高可能抑制菌根真菌生长,为探讨酸性条件下菌根真菌对活性铝的响应机制,以拟青霉(Simplicillium sp.,Si)、细长孢霉(Mortierella elongate,Me)、木霉菌(Trichoderma spp.,Tr)、瓶头霉(Phialocephala,Ph)和葡萄状穗霉(Stachybotrys chartarum,Sc)5种菌根真菌为供试材料,采用PDA液体培养基单种纯培养以pH值为5.5设定3个Al3+浓度梯度,分别为对照(0 mmol·L^-1)、低铝(0.2 mmol·L^-1)和高铝(1.0 mmol·L^-1),研究酸性条件下不同活性铝浓度对菌根真菌的生物量、有机酸分泌以及N、P、K含量等的影响。结果表明:(1)除拟青霉(Si)外,其他菌株均不同程度受活性铝浓度影响,Si生物量随活性铝浓度增加而增加,低铝时比对照增加了238%(P<0.05),而细长孢霉(Me)、木霉菌(Tr)、瓶头霉(Ph)和葡萄状穗霉(Sc)生物量均降低,其中,Ph和Sc分别比对照降低了38.1%和72.5%(P<0.05)。(2)5种菌根真菌分泌有机酸存在显著性差异,Si、Me、Tr和Sc的H+分泌量在高铝浓度时均低于对照,对Si产生显著性差异(P<0.05);仅Me分泌草酸,对照的分泌量是高铝时的1.12倍。(3)5种菌根真菌N、P、K含量随不同活性铝浓度胁迫存在显著性差异,Si和Sc的P、K含量随活性铝浓度增加而显著增加(P<0.05);Me和Ph的N含量随活性铝浓度增加而显著降低(P<0.05),Me的P、K含量分别在低铝和高铝时达到峰值,Tr和Ph的N、P、K含量在低铝时达到峰值而在高铝时受到抑制。(4)Si、Me和Tr受酸铝影响不显著,属耐酸铝型菌株,Ph和Sc属酸铝敏感型菌株。本工作可为天山雪岭云杉森林更新与幼苗存活问题研究的深入开展提供基础依据。

Response of mycorrhizal fungi to acid aluminum stress

Increased concentration of active aluminum in an acidic environment may inhibit the growth of mycorrhizal fungi.In order to further explore the response mechanism of mycorrhizal fungi to active aluminum under acidic conditions in Tianshan forest area,this paper used five mycorrhizal fungi of Simplicillium sp.,Si,Mortierella elongate,Me,Trichoderma spp.,Tr,Phialocephala,Ph and Stachybotrys chartarum,Sc.The test material was set up in a single pure culture of PDA liquid medium at a pH of 5.5 to set three Al3+concentration gradient controls(CK),low Aluminum(0.2 mmol·L^-1),and high Aluminum(1.0 mmol·L^-1).The effects of changes in active aluminum concentration on the biomass,organic acid secretion,and N,P,and K contents of mycorrhizal fungi were studied.The results showed that:(1)Except for Si,other strains were inhibited by active aluminum concentration to varying degrees;Si biomass was positively correlated with active aluminum concentration,and low content of aluminum was increased by 238% compared with control(P<0.05);the biomass of Me,Tr,Ph and Sc decreased,among which,Ph and Sc decreased by 38.1% and 72.5%,respectively.(P<0.05).(2)There were significant differences in the secretion of organic acids by five mycorrhizal fungi.Except for Ph,the H+secretion of Si,Me,Tr and Sc was lower than CK at a high content of aluminum,and there was a significant difference in Si(P<0.05).Only Me detected oxalic acid,and the amount of oxalic acid secretion was 1.12 times higher than CK.(3)The contents of N,P and K in five mycorrhizal fungi were significantly different from the concentration of active aluminum.The contents of P and K in Si and Sc were positively correlated with the concentration of active aluminum(P<0.05).The N content of Me,Ph was significantly negatively correlated with the active aluminum concentration(P<0.05).The P and K contents of Me reached the peak at low and high content of aluminum,respectively.The N,P and K contents of Tr and Ph peaked at low content of aluminum.It was suppressed in high content of aluminum.(4)Si,Me and Tr were not significantly affected by acid aluminum and belonged to the acid-aluminum resistance strain.Ph and Sc were acid-aluminum sensitive strains.