不同条件下连作杭白菊内生菌群的T-RFLP分析

Effect of different treatment on endophytic bacterial communities in continuous cropping of Chrysanthemum morifoliu

通过研究轮作以及有机肥处理对连作杭白菊各器官内生细菌多样性和优势菌属的影响,揭示轮作和有机肥在缓解杭白菊连作障碍中的作用,筛选能够增强连作白菊抗病能力的有益内生菌。实验共设4个处理组,分别为连作处理、轮作处理、连作后施自制蚕沙发酵有机肥处理以及连作后施市售菌肥处理,通过基于16S r DNA的末端标记限制性片段长度多态性技术(terminal restriction fragment length polymorphism,T-RFLP)分析这些处理对杭白菊各器官内生细菌多样性及优势菌属的影响。结果显示,HaeⅢ内切酶能产生更多的TRFs数,比Hinf I酶更适合用来分析杭白菊内生菌多样性。有机肥和菌肥处理组的内生菌Simpson指数与轮作组相近,均高于连作,说明土壤外源微生物的添加导致植物内生菌多样性提高。实验共筛选出18种优势菌属,包括3种厚壁菌、4种放线菌和11种变形菌,其中节杆菌属、链霉菌属、黄杆菌属和分支杆菌属等优势菌属均在轮作组和菌肥组中检测到,而连作组中缺乏,说明添加外源微生物与轮作处理对杭白菊的内生菌群的影响基本类似,同时也说明这些菌的增加可能会通过影响连作白术的生长来缓解连作障碍。此外,比较不同器官中的内生菌的多样性及优势菌数量发现,根中最高,茎次之,叶中最少,这与内生菌侵入植株方式有关。总之,连作导致杭白菊内生细菌多样性降低,而轮作和菌肥处理后均能通过增加土壤微生物的多样性水平从而使连作杭白菊内生细菌多样性提高,最终达到缓解白菊连作障碍的目的。

To reveal the effect of rotation cropping and bacterial manure on the growth of Chrysanthemum morifolium and screen the beneficial endophytic, the diversity of endophytic and dominant genera of different treatment groups were analyzed. Four different treatments were continuous cropping, rotation, seff-made organic fertilizer and commercially available fertilizer, respectively. Endophytic bacterial diversity and dominant genera in different organs were examined using Terminal Restriction Fragment Length Polymorphism （T-RFLP）. The results showed that enzyme Hae IR was more appropriate than enzyme Hinfl because the number of TRFs digested by enzyme Hae Ⅲ was more than that of enzyme Hinfl. In comparison of diversity, the endophytic bacterial communities＇ diversity index in group of cropping rotation and fertilizer was higher than that of continuous cropping which indicated that the addition of exogenous microorganism in soil could increase the diversity of plant endophyte. 18 dominant species were selected, including 3 kinds of Fimficutes, 4 kinds of Actinomycetes and 11 kinds of Proteobacteria. The results of dominant species comparison showed that the number of dominant species in continuous cropping of Ch. morifolium was significantly less than that of the rotation group. Some dominant bacteria in rotation group and fertilizer group such as Arthrobacter, Streptomyces, Streptomyces, Flavobacterium and Mycobacterium were not found in the continuous cropping of Ch. morifolium group. Dominant species of fertilizer treatment group was similar with the rotation group, and the continuous cropping group＇s dominant species was more abundant. It indicates that these bacteria may be able to mitigate hindrance in continuous cropping, especially the Flavobacterium which can decompose the pathogenic fungi is worthy of further attention. Compared with leaves, there are more dominant species in roots and stems. The diversity of edophytic bacterial commu- nities in continuous cropping of Ch. morifolium stays below than that in the rotation of Ch. morifolium, and fertilizer treatment can increase the diversity of continuous cropping so that it could mitigate hindrance in continuous cropping.