Grafting is a basic technique which is widely used to increase yield and enhance biotic and abiotic stress tolerance in plant production. The diversity and interactions of rhizobacterial assemblages shaped by grafting are important for the growth of their hosts but remain poorly understood. To test the hypothesis that plant grafting shapes complexity and co-occurrence of rhizobacterial assemblage, four types of plants, including ungrafted bottle gourd (B), ungrafted watermelon (W), grafted watermelon with bottle gourd rootstock (W/B), and grafted bottle gourd with watermelon rootstock (B/W), were cultivated in two soil types in a greenhouse, and the rhizosphere bacterial communities were analyzed by 16S rRNA gene high-throughput sequencing. Both the soil type and grafting significantly influenced the bacterial community composition. Grafting increased bacterial within-sample diversity in both soils. Core enriched operational taxonomic units (OTUs) in the W/B rhizosphere compared with the other three treatments (B, W, and B/W) were mainly affiliated with Alphaproteobacteria, Deltaproteobacteria, and Bacteroidetes, which are likely related to methanol oxidation, methylotrophy, fermentation, and ureolysis. Co-occurrence network analysis proved that grafting increased network complexity, including the number of nodes, edges, and modules. Moreover, grafting strengthened the structural robustness of the network in the rhizosphere, while ungrafted watermelon had the lowest network robustness. Homogeneous selection played a predominant role in bacterial community assembly, and the contribution of dispersal limitation was increased in grafted watermelon with bottle gourd rootstock. Grafting increased the diversity and transformed the network topology of the bacterial community, which indicated that grafting could improve species coexistence in the watermelon rhizosphere.

嫁接是一项基本技术，已广泛用于提高产量并增强植物生产中的生物和非生物胁迫耐受性。通过嫁接形成的根瘤菌群的多样性和相互作用对于它们的宿主的生长很重要，但仍然知之甚少。为了检验假说植物嫁接会影响根瘤菌的复杂性和共生性，提出了四种类型的植物，包括未嫁接的葫芦（B），未嫁接的西瓜（W），带有葫芦砧木的嫁接的西瓜（W / B）和嫁接的在温室中的两种土壤类型中种植带西瓜砧木（B / W）的葫芦，并通过16S rRNA基因高通量测序分析了根际细菌群落。土壤类型和嫁接都显着影响细菌群落组成。嫁接增加了两种土壤中细菌的样本内多样性。与其他三种处理方法（B，W和B / W）相比，W / B根际中富含核心的操作分类单位（OTU）主要与丙酸杆菌，三角洲细菌和拟杆菌属有关，这很可能与甲醇氧化，甲基营养相关，发酵和尿素分解。共现网络分析证明，嫁接会增加网络的复杂性，包括节点，边缘和模块的数量。此外，嫁接增强了根际网络的结构坚固性，而未嫁接的西瓜具有最低的网络坚固性。均质选择在细菌群落的组装中起主要作用，而在嫁接西瓜与葫芦根砧木中，分散限制的贡献增加了。