两种栽培型广藿香内生真菌群落组成变化

Community composition changes of endophytic fungi from two cultivated species of Pogostemon cablin

为探索内生真菌与广藿香互作间对宿主活性成分形成机制的影响,该研究以成分差异较大的牌香和湛香为对象,采用传统形态学方法对所获菌株归类,通过真菌通用引物ITS1/ITS4扩增菌株rDNA-ITS序列,鉴定其分类地位并研究其多样性。结果表明:(1)用PDA和LBA培养基对苗期、分枝期和成株期广藿香茎叶组织块进行内生真菌分离,共获得3070株菌株,其中牌香(PX)分离出1624株,鉴定出1319株,分属于36属;湛香(ZX)分离出1446株,鉴定出994株,分属于33属。牌香分离出7种特有内生真菌,分别为香柱菌(Epichloe typhina)、盘长孢状刺盘孢菌(Colletotrichum gloeosporioides)、座腔孢菌(Botryosphaeria sp.)、丝核菌(Rhizoctonia sp.)及截盘多毛孢菌(Truncatella sp.),并首次分离到疫霉菌(Phytophthora sp.)和指疫霉菌(Sclerophthora sp.),这2种菌属于卵菌门内生菌。湛香分离出拟青霉菌(Paecilomyces sp.)和尾孢菌(Cercospora sp.)2种特有内生真菌。(2)牌香和湛香优势内生真菌相同,均为链格孢菌(Alternaria sp.)和刺盘孢菌(Colletotrichum sp.),其中牌香中相对分离频率为9.48%和7.81%,湛香为10.16%和8.65%。(3)从苗期到成株期,牌香和湛香内生真菌定殖率逐渐增高,依次为牌香8月(97.78%)>7月(72.50%)>5月(55.28%);湛香8月(91.11%)>7月(63.06%)>5月(46.67%)。平均定殖率为牌香75.19%,湛香66.95%。(4)随着生长期延长,牌香和湛香内生真菌多样性呈递增趋势,同时2种广藿香内生真菌平均相似性系数为0.86。可见,牌香和湛香内生真菌种类丰富,各有独特的内生真菌,且不同生长期内生真菌种群组成不同。该研究结果为筛选活性内生真菌菌株,探究内生真菌影响广藿香活性成分合成与积累奠定了基础。

In order to explore the effects of the interaction between endophytic fungi and patchouli on the formation mechanism of active components,a laboratory experiment was conducted for investigating the endophytic fungi of Pogostemon cablin cv.shipaiensis and P.cablin cv.zhanjiangensis with chemical component difference.The strains were classified by traditional morphological methods firstly,and then the rDNA-ITS sequences of the strains were amplified by the common fungal primer ITS1/ITS4 to identify their taxonomic status and their diversities.The results were as follows:(1)A total of 3070 strains were isolated from the stem and leaf tissues of patchouli in seedling,branching and adult stages by PDA and LBA culture media.The 1624 strains of endophytic fungi from P.cablin cv.shipaiensis were isolated and 1319 strains were identified,which belonged to 36 genera.Seven endemic endophytic fungi were isolated from P.cablin cv.shipaiensis,including Epichloe typhina,Colletotrichum gloeosporioides,Botryosphaeria sp.,Rhizoctonia sp.,Truncatella sp.,Phytophthora sp.,and Sclerophthora sp.,and the later two belonging to Oomycete were isolated for the first time.There were 1446 strains isolated from P.cablin cv.zhanjiangensis,and 994 strains were identified,which were belonging to 33 genera.Among them,there were two endemic endophytic fungi in P.cablin cv.Zhangjiangensis,including Paecilomyces sp.and Cercospora sp.(2)The dominant endophytic fungi were Alternaria sp.and Colletotrichum sp.in two kinds of cultivated patchouli.The relative separation frequencies of the Alternaria sp.and Colletotrichum sp.were 9.48%and 7.81%in P.cablin cv.shipaiensis,and were 10.16%and 8.65%in P.cablin cv.zhanjiangensis.(3)The colonization rates of endophytic fungi gradually increased with the growth of patchouli from seedling to adult stages,which were Aug.(97.78%)>Jul.(72.50%)>May(55.28%)in P.cablin cv.shipaiensis,and Aug.(91.11%)>Jul.(63.06%)>May(46.67%)in P.cablin cv.zhanjiangensis.The average colonization rates were 75.19%and 66.95%.(4)There were a positive correlation between the growth periods and the Shannon index,which increased with the growth of patchouli.The average sorenson similarity index was 0.86.Obviously,P.cablin cv.shipaiensis and P.cablin cv.Zhangjiangensis had a large population of endophytic fungi and had their own endemic endophytic fungi,but the community structure was significantly different.These results lay a foundation for screening active strains and exploring the effect of endophytic fungi on the synthesis and accumulation of active components of patchouli.