Aims

The use of rootstock is effective at protecting plants from soil-borne diseases, however, the underlying mechanisms remain to be elucidated.

Methods

In this study, the root-associated microbiomes and root exudate profiles of rootstock (grafted) and self-rooted (ungrafted) watermelon plants grown in plastic shelters heavily infected with Fusarium oxysporum f. sp. niveum (FON) were characterized.

Results

We showed that grafting markedly controlled Fusarium wilt disease, greatly reduced FON abundance in the rhizoplane and endosphere, and improved microbial diversity across rhizosphere to endosphere in continuous cropping soils. We further found that grafting significantly changed the composition of root-associated microbiomes, improved microbial association network complexity, and had potential beneficial bacterial taxa like Streptomycetales and Sphingomonadales, and fungal taxa like Capnodiales and Sebacinales significantly enriched in grafted watermelon. The grafted watermelon also possessed a distinct root exudate profile from the ungrafted watermelon and rootstock plants, with organic acids (potential autotoxins) significantly depleted but more plant defense-related metabolites such as organosulfur compounds and benzenoids enriched in comparison to ungrafted watermelon.

Conclusion

Together, our results suggest that grafting facilitates plant disease resistance potentially by direct antagonism effect through root exudates and indirectly by shaping the protective root-associated microbiomes.

中文翻译：

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砧木通过在连作土壤中塑造保护性的根相关微生物组和代谢物，从枯萎病中拯救西瓜

目标

砧木的使用可有效保护植物免受土传疾病的侵害，但其潜在机制仍有待阐明。

方法

在这项研究中，在严重感染尖孢镰刀菌的塑料棚中生长的砧木（嫁接）和自生根（未嫁接）西瓜植物的根系相关微生物组和根分泌物概况。sp。niveum (FON) 进行了表征。

结果

我们表明嫁接显着控制镰刀菌枯萎病，大大降低了根际和内生层中的 FON 丰度，并改善了连作土壤中从根际到内生层的微生物多样性。我们进一步发现嫁接显着改变了根相关微生物组的组成，改善了微生物关联网络的复杂性，并具有潜在的有益细菌类群，如链霉菌和鞘氨醇单胞菌，以及真菌类群，如 Capnodiales 和 Sebacinales，在嫁接的西瓜中显着富集。嫁接的西瓜也具有与未嫁接的西瓜和砧木植物不同的根系分泌物特征，与未嫁接的西瓜相比，有机酸（潜在的自身毒素）显着耗尽，但更多的植物防御相关代谢物，如有机硫化合物和苯类化合物富集。

结论

总之，我们的研究结果表明，嫁接可能通过根分泌物的直接拮抗作用和通过塑造保护性根相关微生物组间接促进植物抗病性。