Tan Yong, Cui Yinshan, Li Haoyu, Kuang Anxiu, Li Xiaoran, Wei Yunlin, Ji Xiuling
Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China.
Department of Biology, University of Texas Rio Grande Valley, Edinburg, Texas.
J Basic Microbiol. 2017 Apr;57(4):337-344. doi: 10.1002/jobm.201600464. Epub 2017 Jan 6.
Rhizobacteria and endophytic bacteria play important roles in protecting host plants from infection by phytopathogens, which cause soil-borne diseases and severely impair plant health. Panax notoginseng is negatively affected by continuous cropping and becomes vulnerable to attack by microbial pathogens. In the present study, culture-independent Illumina MiSeq was used to investigate root-endophytic and rhizospheric bacteria in response to continuous cropping of P. notoginseng. Numbers of rhizospheric bacteria decreased with continuous P. notoginseng cropping, while the effects of continuous cropping on endophytic bacteria were not statistically significant. Bacterial diversity was higher in healthy P. notoginseng rhizospheric soils and roots than in those of diseased P. notoginseng. The most dominant phyla detected during continuous cropping were Proteobacteria, Cyanobacteria, Actinobacteria, and Acidobacteria. The genera Pseudomonas, Rhodoplanes, Candidatus Solibacter, and Streptomyces were dominant in P. notoginseng rhizospheric soils and roots. Erwinia, Stenotrophomonas, Pseudomonas, and Sphingobium were specifically detected in relatively high proportions among root-rot rhizospheric bacteria and endogenous root bacteria in plants under continuous cropping, suggesting that they may be the pathogens responsible for the negative effects of continuous cropping on P. notoginseng. Based on canonical correspondence analysis of the bacterial communities that were identified from healthy plants and fallow soils, total phosphorus (P), pH, and organic soil matter exerted the greatest impacts upon bacterial community composition during continuous cropping. In general, continuous cropping practices for P. notoginseng and severe root-rot disease notably affected the community structure and the diversity of rhizospheric and root endophytic bacteria. Our study elucidated the ecological significance of microbial communities in healthy plant maintenance, and our results may inform biological control strategies during the continuous cropping of P. notoginseng.
根际细菌和内生细菌在保护宿主植物免受植物病原体感染方面发挥着重要作用，这些病原体可导致土传病害并严重损害植物健康。三七受到连作的负面影响，容易受到微生物病原体的攻击。在本研究中，采用非培养的Illumina MiSeq技术来研究三七连作对根内生细菌和根际细菌的影响。随着三七连作，根际细菌数量减少，而连作对内生细菌的影响无统计学意义。健康三七根际土壤和根中的细菌多样性高于患病三七。连作期间检测到的最主要门类为变形菌门、蓝细菌门、放线菌门和酸杆菌门。假单胞菌属、红游动菌属、类芽孢杆菌属和链霉菌属在三七根际土壤和根中占主导地位。在连作植物的根腐根际细菌和内生根细菌中，欧文氏菌属、嗜麦芽窄食单胞菌属、假单胞菌属和鞘氨醇单胞菌属的检出比例相对较高，这表明它们可能是导致三七连作负面影响的病原体。基于对健康植物和休闲土壤中细菌群落的典范对应分析，总磷（P）、pH值和土壤有机质在连作期间对细菌群落组成影响最大。总体而言，三七连作和严重根腐病显著影响根际和根内生细菌的群落结构和多样性。我们的研究阐明了微生物群落在维持植物健康中的生态意义，我们的结果可能为三七连作期间的生物防治策略提供参考。
