不同化学型和季节变化对茅苍术内生真菌群落多样性的影响

Effects of different chemotypes and seasonal dynamic variation on the species diversity of endophytic fungal communities harbored in Atractylodes lancea

对茅山型茅苍术(MA)和湖北型茅苍术(HA)的内生真菌多样性进行调查,分析二者之间优势菌群和特异菌群的差异。将两种化学型的茅苍术移栽至同一环境中,分别于春季、夏季、秋季3个季节采集叶片进行内生真菌的分离、鉴定和多样性分析。调查一共得到530株内生真菌,总分离率为58.89%,通过形态学特征和ITS序列鉴定归结为20个属。MA内生真菌分离率要高于HA,二者的真菌多样性构成有一定差异性。MA和HA内生真菌的优势菌群呈基本重合现象,主要集中于交链孢属、球座菌属、刺盘孢属等几个属;而二者之间的特异菌群显示出差异性,MA的特异菌群为Leptospora属、支顶孢属、壳针孢属等,HA特异菌群为白僵菌属、轮枝孢属、毛壳菌属等。随着季节的变化,内生真菌群落显示出一定的演替规律。夏季内生真菌的多样性高于春季和秋季。

Atractylodes lancea（ Thunb.） DC is a Chinese medicinal herb. The Maoshan mountain area is famous for producing the authentic medicinal herb of A. lancea. Volatile oils from A. lancea show antimicrobial activity and include the characteristic atractylone,!-eudesmol,hinesol,and atractylodin. Because the active compositions are different,A. lancea samples from different places are divided into the Maoshan chemotype and the Hubei chemotype. To study the formation of the authentic medicinal herb,the endophytic fungal diversity of the two chemotypes of A. lancea was analyzed. Maoshan chemotype A. lancea（ MA） and Hubei chemotype A. lancea（ HA） were transplanted from each habitat and cultivated in the same environmental conditions. The leaves were selected,and endophytic fungi were isolated and identified during spring,summer,and autumn in 2011.The results indicated that plentiful fungal diversity was present in A. lancea. A total of 530 endophytic fungi were isolated from the leaves of A. lancea,with an isolation rate of 58. 89%. All of the isolates were identified based on their morphological characteristics and molecular phylogeny; the isolates belonged to 20 genera. The species in Alternaria,Colletotrichum,and Guignardia were the predominant groups of fungi,and their relative isolation frequencies were 36.04%,19.43%,and 9.62%,respectively,which were much greater than the isolation frequencies of other genera.The isolation rate（ IR） of endophytic fungi from MA was 70. 22%,and that from HA with 47. 53%. Thediversity index,which was determined by the Shannon-Wiener index（ H’）,revealed that the diversity of endophytic fungi in MA（ H’ = 2.16） is somehow higher than that in HA（ H’ = 1.83）. Sorenson’s similarity index between MA and HA was0.67,which indicated that the community composition of endophytic fungi from the two types of A. lancea was different to some extent. The dominant genera of endophytic fungi in the two chemotypes of A. lancea showed basic similarities; these genera included Alternaria,Guignardia,and Colletotrichum. However,some genera were chemotype-specific. The MAspecific genera included Leptospora,Acremonium,and Septoria; the HA-specific genera included Beauveria,Verticillium,and Chaetomium.The diversity of endophytic fungi among different seasons presented certain successive patterns. The IR in summer was the highest（ IR = 71.33%） and was followed by autumn（ IR = 63.00%） and spring（ IR = 42.33%）. This suggested that the isolation of endophytic fungi increased from spring to summer and then declined slightly in autumn. The Shannon-Wiener index（ H’） indicated that greater endophytic fungal diversity was observed during summer（ H’ = 2.20）than spring（ H’ = 1.64） and autumn（ H’ = 1.88）. With respect to seasonal factors,Sorenson’s similarity index between spring and summer was 0.71,and that between summer and autumn was 0.76,while that between spring and autumn was0. 64. This indicated that there were some differences in the community composition of endophytic fungi among different seasons,but the differences were not significant. The dominant genera of endophytic fungi of A. lancea isolated in different seasons included Alternaria,Guignardia,and Colletotrichum; all of these genera were observed during every season,showing a wide seasonal distribution. The results of this study offer information about the differences in endophytic fungal diversity of two chemotypes of A. lancea under the same environmental conditions; these results also reveal seasonal variation in the endophytic fungi of A. lancea. Differences in the community composition of endophytic fungi between two chemotypes of A. lancea may have an important effect on the genuineness of the medicinal herb. These results are important for understanding the formation of the authentic medicinal herb of A. lancea.