新疆黄萎病发病程度不同棉田土壤细菌群落结构差异分析

新疆棉区棉花黄萎病发生危害严重,提高该病的生态防控技术对实现棉花"化肥、农药"减施增效有重要意义。文章以阿克苏、石河子和库尔勒三地棉花黄萎病不同发生程度棉田土壤为研究对象,利用高通量测序技术对土壤细菌种群结构进行研究,并分析土壤理化性质与细菌多样性及种群结构的相关性,以期揭示棉田土壤的细菌群落结构差异及主要影响因子,为提高新疆棉花黄萎病生态防控技术提供依据。结果表明,在97%相似水平上,阿克苏、库尔勒重病棉田土壤细菌的OTU数量及ACE、Chao1、Shannon-Wiener指数均分别与其对照田土壤无显著差异,石河子重病田土壤细菌的ACE、Chao1指数均显著低于其对照田,而Shannon-Wiener指数显著高于对照田。聚类分析发现,阿克苏、石河子重病田均分别与对照田土壤的细菌群落组成差异显著,而库尔勒重病田与其对照田土壤细菌群落组成差异较小。在属水平上,阿克苏重病田土壤中有益菌群溶杆菌属(Lysobacter)和假单胞菌属(Pseudomonas)的丰度分别为3.67%和3.15%,均显著高于无病田对照(2.35%和0.18%),而芽胞杆菌属(Bacillus)和链霉菌属(Streptomyces)的丰度在阿克苏、石河子、库尔勒三地重病田与对照田之间均无显著差异。差异标记分析同样发现在阿克苏重病田中显著富集了假单胞菌目(Pseudomonadales),在石河子重病田中显著富集了放线菌门(Actinobacteria)。相关分析表明,棉田土壤细菌的OTU数量、Alpah多样性指数与土壤pH值、全钾含量呈正相关,与总盐含量、碳氮比呈负相关,与有机质、全氮、全磷含量及棉田发病程度无明显相关,土壤pH值、总盐含量是影响土壤细菌多样性的主要因子。

Characteristics of Soil Bacterial Community Structure in Cotton Fields with Different Incidence of Verticillium Wilt in Xinjiang

Since Verticillium wilt has caused severe damage to the cotton region in Xinjiang,an improved ecological prevention and control of the disease will help increase the efficiency of chemical fertilizers and pesticides while reduce their application in cotton fields.Therefore,the soil in the cotton fields with different degrees of Verticillium wilt in Aksu,Shihezi and Korla was selected as the object of study.The population structure of soil bacteria was investigated by high-throughput sequencing.How the physical and chemical properties of soil correlate with bacterial diversity and population structure was also analyzed,so as to reveal the differences of bacterial community structure and the main influencing factors in cotton soil.It is expected that the findings can provide a basis for improving the ecological prevention and control of Verticillium wilt in Xinjiang.The results showed that:at a similarity threshold of 97%,the number of OTUs,ACE index,Chao1 index and Shannon-Wiener index of soil bacteria in severely affected cotton fields of Aksu and Korla had no significant difference with those in the control soil.In Shihezi,the ACE index and Chao1 index of soil bacteria in severely affected cotton fields were significantly lower than those in mildly affected cotton fields,but their Shannon-Wiener index was significantly higher than that in mildly affected cotton fields.A cluster analysis indicated that the bacterial community composition of soil in severely affected cotton fields of Aksu and Shihezi was significantly different from that in control fields,but the bacterial community composition of soil in severely affected cotton fields of Korla was only slightly different from that in control fields.In terms of bacteria genera,the abundance of Lysobacter and Pseudomonas in severely affected cotton fields of Aksu(3.67%and 3.15%)was significantly higher than that in control fields(2.35%and 0.18%).However,the abundance of Bacillus and Streptomyces in severely affected cotton fields of Aksu,Shihezi and Korla did not show any significant difference with that in control fields.A labeling analysis revealed that Pseudomonadales were significantly enriched in severely affected cotton fields of Aksu,while Actinobacteria were significantly enriched in severely affected cotton fields of Shihezi.A correlation analysis suggested that the number of OTUs and Alpah diversity index of soil bacteria in cotton fields would be positively correlated with soil pH and total potassium,negatively correlated with total salt and carbon-nitrogen ratio,but not significantly correlated with organic matter,total nitrogen,total phosphorus and extent of disease in cotton fields.In other words,soil pH and total salt are the main factors that affect bacterial diversity in soil.