西瓜根际土壤细菌群落多样性对枯萎病发生的影响

通过高通量测序分析不同栽培条件下西瓜患枯萎病与健康植株根际土壤细菌群落差异，为克服西瓜连作障碍提供土壤生物学的理论依据。以西瓜品种‘早佳8424’为材料，采用Illumina Hiseq 平台进行测序，对其根际土样微生物16S(V4)区域进行扩增子测序分析，比较不同栽培条件下西瓜感病与健康植株根际土壤中细菌多样性变化，探讨影响西瓜枯萎病发生的关键细菌。连作健康组中共获得234895条序列，分归于11230 个OTUs；连作发病组中共获得224092 条序列，分归于11228 个OTUs；非连作健康组中共获得220963 条序列，分归于10068 个OTUs；非连作发病组中共获得231746 条序列，分归于10248 个OTUs。门水平上，变形菌门(Proteobacteria)在各组分中占比均为最高，分别为非连作健康土55.61%、非连作发病土60.84%、连作健康土46.06%、连作发病土47.21%，在非连作土壤中占比高于连作土壤11.59%。另外，连作健康组与非连作健康组存在组间差异显著物种，梭菌纲(Clostridia)在连作健康组中特有，而加玛变形菌纲(Gammaproteobacteria)仅存在非连作健康组中。而在属水平上，非连作组中丰度高的有水恒杆菌属(Mizugakiibacter)、潘多拉菌属(Pandoraea)、热单胞菌属(Thermomonas)、乳杆菌属(Acidobacterium)，且RH组中Taibaiella、戴氏菌属(Dyella)和噬几丁质菌属(Chitinophaga)含量显著增高。对不同处理的综合分析表明，发病植株与健康植株在非连作条件下，根际土壤细菌群落结构差异明显；发病植株的根际土壤细菌群落在不同栽培条件下的组成结构不同。根际土壤细菌群落结构、数量和种类是影响西瓜枯萎病发生的主效环境因子之一。

Watermelon Rhizosphere Soil Bacterial Diversity Affects the Occurrence of Fusarium Wilt

To explore the effect of bacterial community diversity of watermelon rhizosphere soil on the occurrence of fusarium, the authors analyzed the rhizosphere bacterial of wilted and healthy plants under both the continuous cropping field soil and rotated cropping field soil. The V4 region of the 16S rRNA gene in bacterial DNA was amplified using the polymerase chain reaction technique, and sequenced by the Illumina Hiseq platform, to conduct a diversity analysis of the soil bacteria microbial community composition of different samples. A total of 234895 tags of high-quality reads were obtained in CH (continuous cropping, healthy), 224092 tags in CW (continuous cropping, wilted), 220963 tags in RH (rotated cropping, healthy), 231746 tags in RW(rotated cropping, wilted), respectively. And the tags were clustered into CH 11230, CW 11228, RH 10068, RW 10248 microbial operational taxonomic units (OTUs). At phylum level, Proteobacteria accounted for the highest ratio in all the four treatments, respectively as RH 55.61% , RW 60.84% , CH 46.06%, CW 47.21%, and the proportion in non-continuous cropping was averagely 11.59% higher than that of continuous cropping. In addition, there was a significant difference between CH and RH, Clostridia was specifically in CH, while Gammaproteobacteria existed only in RH. However, in the genus top 35 bacteria population, the abundance of Mizugakiibacter, Pandoraea, Thermomonas and Acidobacterium in rotate cropping was apparently higher than that in continuous cropping. And Taibaiella, Dyella and Chitinophaga in RH were more abundant compared with other treatments. The results showed that the bacterial community diversity in rhizosphere soil of continuous cropping was higher than that in rotate cropping; the structures of bacterial communities in rhizosphere soil of wilted plants and healthy plants were significantly different under rotate cropping condition; the structures of bacterial community were different under different cultivation conditions. In conclusion, the bacteria community structure, quantity and variety of rhizosphere soil are one of the main environmental factors that affect the occurrence of watermelon wilt.