抗、感青枯病桑树根际细菌群落结构与多样性

Rhizosphere Bacterial Community and Diversity at Fields of Wilt Resistant or Susceptible Mulberry Trees

【目的】通过抗、感青枯病桑树根际土壤细菌群落结构与多样性分析,阐明根际细菌群落与桑树抗、感青枯病的相关性。【方法】采用Illumina MiSeq测序技术对抗青枯病桑树基因型(抗青283×抗青10)和感病基因型(桂桑优62)根际细菌的16S rRNA基因V3-V4区进行扩增,高通量测序后比较分析了其根际细菌群落结构与多样性。【结果】①抗、感青枯病桑树根际土壤的优势菌门为变形菌门、放线菌门、酸杆菌门、芽单胞菌门和拟杆菌门,优势菌属为MND1、Gaiella、硝化螺菌属、Haliangium和链霉菌属;②抗、感青枯病桑树根际土壤细菌群落Alpha多样性无显著差异,但经NMDS排序,则可显著区分(stress=0.005<0.05),其中抗性基因型根际土壤中具有重要作用的细菌类群较多,包括:硝化螺旋菌纲、酸杆菌纲、硝化螺旋菌目、索利氏菌目、酸杆菌目、硝化螺旋菌科、酸杆菌目未培养科、索利氏菌科Subgroup 3和Subgroup 2未培养科,而敏感基因型桂桑优62根际重要作用的细菌类群则主要为Ilumatobacteraceae和TRA320 Other两个科。③抗、感青枯病桑树根际细菌差异COG类目为763,仅占17.25%。【结论】抗、感青枯病桑树根际土壤细菌群落丰富度和多样性虽无显著差异,但其重要作用的类群显著不同,说明桑树根际土壤细菌群落结构可能与种质对青枯病的抗性具有相关性。本结果将为进一步研究桑树根际微生态特征、筛选有益功能菌株并用于桑青枯病的有效防控具有重要意义。

【Objective】Structure and diversity of rhizosphere bacterial communities at fields of mulberry trees resistant(QZ2 K)or susceptible(QZ2 G)to wilt disease were studied.【Method】The V3-V4 regions of 16 S rRNA in rhizosphere bacteria were amplified and sequenced using high-throughput sequencing technology on Illumina MiSeq to determine the bacterial community structure,diversity,and functions.Results from the two field samples were compared.【Result】(1)At phylum and genus levels,the dominant rhizosphere bacteria were similar at QZ2 K(Kangqing 283×Kangqing 10 mulberry field)and at QZ2 G(Guisangyou 62 mulberry field).The phyla included Proteobacteria,Actinobacteria,Acidobacteria,Gemmatimonadetes,and Bacteroidetes,while the genera consisted of MND1,Gaiella,Nitrospira,Haliangium,and Streptomyces.(2)Although no significant difference in the alpha diversity of the bacteria communities at the two different fields,the NMDS ordination showed significant differences(stress 0.005<0.05).At QZ2 K,the bacteria related to significant metabolic functions were Nitrospira,Acidobacteriia,Nitrospirales,Solibacteraies,Acidobacteriales,Nitrospiraceae,and the uncultured Acidobacteria,Solibacteraies Subgroup 3,and Solibacteraies Subgroup 2.At QZ2 G,only Ilumatobacteraceae and TRA3-20-other were identified.(3)According to the Wilcoxon signed rank test,the 763 different rhizosphere bacteria orthologs identified were only 17.25%of all COG orthologs on both fields.【Conclusion】There were no significant differences in the richness and diversity of rhizosphere bacteria community between the two fields.However,the bacteria associated with significant functions differed significantly between them,which could well be the species that made the difference in the occurrence of wilt disease on the mulberry plants.The information obtained in this study was of value for further studies on the microecological characteristics of mulberry rhizosphere as well as selection and application of functional bacteria for wilt control.