水旱轮作模式下马铃薯根际土壤细菌群落多样性分析

Diversity analysis of bacterial community in potato rhizosphere soil under the mode of paddy-upland rotation

【目的】比较水旱轮作与旱地轮作两种种植模式下的马铃薯根际土壤及病株块茎的细菌群落多样性,为利用土壤细菌多样性优化马铃薯种植模式和防治马铃薯病害提供科学依据。【方法】分别采集前作为水稻的水旱轮作和前作为玉米的旱地轮作模式下马铃薯根际土壤样品(旱地轮作和水旱轮作健康马铃薯根际土壤样品分别记为HD.J和SH.J,旱地轮作和水旱轮作发病马铃薯根际土壤样品分别记为HD.B和SH.B)及马铃薯病株块茎样品(旱地轮作和水旱轮作发病马铃薯块茎样品分别记为P.HD.B和P.SH.B),基于高通量测序技术对样品中细菌16S rDNA的V3~V4区域进行测序,分析2种种植模式下的马铃薯根际土壤样品和病株块茎样品的细菌种类及丰度差异。【结果】对马铃薯根际土壤样品及病株块茎样品的细菌多样性分析结果显示,HD.J、HD.B、SH.J和SH.B的细菌种类(OTU数目)、丰富度(Chao1指数)及多样性(Shannon指数)均高于P.SH.B和P.HD.B,且健株根际土壤细菌群落丰富度高于病株土壤。马铃薯种植模式是影响根际土壤细菌群落变化的最主要因素,贡献率为39.1%,而马铃薯植株健康状况是影响根际土壤细菌群落变化的第二大因素,贡献率为34.7%。病株根际土壤样品中,HD.B无丰度在1.00%以上的优势种,而SH.B特有的优势种中包含软腐病果胶杆菌(Pectobacterium carotovorum)、雷尔氏菌(Ralstonia solanacearum)和不动杆菌(Acinetobacter rudis),相对丰度分别为2.03%、1.46%和1.22%,其中软腐病果胶杆菌和雷尔氏菌是马铃薯的主要病原细菌,可分别导致马铃薯黑胫病和青枯病发生。病株块茎样品中,P.SH.B除了包含P.HD.B检测到的23个属,还有5个属是其所特有;P.SH.B特有的5个属中有3个优势属在SH.B中未检测到。HD.B特有的优势功能是产甲烷作用,相对丰度为1.18%;SH.B特有的优势功能包括硝酸盐呼吸作用、氮呼吸作用、亚硝酸盐呼吸作用、亚硝酸盐氨化作用和硝酸盐氨化作用,均属于氮利用及代谢功能,相对丰度为1.48%~1.95%。【结论】与旱地轮作模式相比,水旱轮作模式可提高马铃薯根际土壤的细菌群落多样性,但在该种植模式下要重点预防马铃薯发生细菌性病害。

【Objective】The microbial community diversity in rhizosphere soil and tuber between paddy-upland rotation and upland rotation in potato planting was compared in order to optimize potato planting modes and provide scientific basis to develop potato industry from the perspective of plant-microbiome ecology.【Method】Soil samples of potato rhizosphere and tuber samples of potato diseased plants were collected from the rotation of rice paddy-upland rotation and maize upland rotation,respectively.The rhizosphere soil samples of healthy potato in upland rotation and paddy-upland rotation were marked with HD.J and SH.J,respectively.The rhizosphere soil samples of diseased potato in upland rotation and paddy upland rotation were marked with HD.B and SH.B,respectively.Tuber samples of diseased potato in upland rotation and paddy-upland rotation were marked with P.HD.B and P.SH.B,respectively.V3-V4 region of 16S rDNA amplicon of bacteria in the rhizosphere soil and tuber samples were sequenced using high throughput sequencing.Then the bacteria species and abundance differences of potato rhizosphere soil samples and diseased tuber samples in two cultivation modes were analyzed.【Result】The results of bacterial diversity analysis of rhizosphere soil samples and tuber samples of diseased potato showed that the bacterial species,richness(Chao1 index)and diversity(Shannon index)of HD.J,HD.B,SH.J and SH.B were higher than those of P.SH.B and P.HD.B.The abundance of bacterial community in rhizosphere soil of healthy plants was higher than that of diseased plants.Potato planting pattern was the most important factor affecting the change of bacterial community in soil,with the contribution rate of 39.1%,while the health status of potato plant was the second most important factor with the contribution rate of 34.7%.There was no dominant species with abundance of more than 1.00%in HD.B,while the dominant species in SH.B included Pectinium carotovorum,Ralstonia solanacearum and Acinetobacter rubis with abundances of 2.03%,1.46%and 1.22%,respectively.Among them,Pectinobacteria and Ralstonia were the main potato pathogens,which could cause potato black leg and potato bacterial wilt,respectively.In the tuber samples of diseased plants,P.SH.B contained not only twenty-three genera detected from P.HD.B,but also contained five genera which were endemic to P.SH.B.Among the five genera which endemic to P.SH.B,three dominant genera were not detected in SH.B.The dominant function of HD.B was methanogenesis,with a relative abundance of 1.18%.In SH.B,the dominant function was nitrogen utilization and metabolism,containing nitrate respiration,nitrogen respiration,nitrite respiration,nitrite ammonification and nitrate ammonification,with the relative abundance of 1.48%-1.95%.【Conclusion】Compared with the upland rotation mode,the paddy-upland rotation mode can improve the bacterial community diversity of potato rhizosphere soil,but the bacterial diseases of potato should be prevented under this planting mode.