Xu Lihui, Nicolaisen Mogens, Larsen John, Zeng Rong, Gao Shigang, Dai Fuming
Institute of Eco-Environmental Protection, Shanghai Academy of Agricultural Sciences, Shanghai, China.
Shanghai Key Laboratory of Protected Horticultural Technology, Shanghai, China.
Front Microbiol. 2020 Dec 17;11:605622. doi: 10.3389/fmicb.2020.605622. eCollection 2020.
Interactions of pathogen infection, host plant resistance, and fungal communities are poorly understood. Although the use of resistant watermelon cultivars is an effective control measure of watermelon wilt disease, fungal communities may also have significant effects on the development of the soil-borne pathogen complexes. We characterized the root and rhizosphere fungal communities associated with healthy and diseased watermelons of three different cultivars with different susceptibilities toward wilt disease by paired-end Illumina MiSeq sequencing. Thirty watermelon plants including highly wilt-resistant, moderately resistant, and susceptible cultivars were collected from a greenhouse, half of which showing clear wilt symptoms and the other half with no symptoms. Patterns of watermelon wilt disease and the response of the fungal communities varied among the three cultivars. The amount of the pathogen f. sp. was higher in diseased root and rhizosphere samples, particularly in the susceptible cultivar, and was significantly positively correlated with the disease index of Fusarium wilt. Plant health had significant effects on root-associated fungal communities, whereas only the highly resistant cultivar had significant effects only on the rhizosphere fungal communities. Co-occurrence networks revealed a higher complexity of fungal communities in the symptom-free roots compared to diseased roots. In addition, networks from roots of the highly resistant plants showing symptoms had a higher complexity compared to the susceptible cultivars. Keystone species were identified for the plants with different symptom severity and the different cultivars in the root and rhizosphere, such as , and . Overall, the most important factor determining fungal communities in the roots was plant symptom severity, whereas in the rhizosphere, plant genotype was the most important factor determining fungal communities.
病原体感染、寄主植物抗性和真菌群落之间的相互作用尚不清楚。虽然使用抗病西瓜品种是防治西瓜枯萎病的有效措施，但真菌群落也可能对土传病原体复合体的发展产生重大影响。我们通过双末端Illumina MiSeq测序对三种不同品种的健康和患病西瓜的根和根际真菌群落进行了表征，这三种品种对枯萎病的易感性不同。从温室中收集了30株西瓜植株，包括高抗枯萎病、中抗枯萎病和易感品种，其中一半表现出明显的枯萎症状，另一半没有症状。三种品种的西瓜枯萎病发病模式和真菌群落的反应各不相同。病原菌f. sp. 在患病根和根际样品中的数量较高，尤其是在易感品种中，并且与枯萎病的病情指数显著正相关。植株健康状况对根际相关真菌群落有显著影响，而只有高抗品种仅对根际真菌群落有显著影响。共现网络显示，与患病根相比，无症状根中的真菌群落更为复杂。此外，有症状的高抗植株根际的网络比易感品种更为复杂。已确定了根和根际中具有不同症状严重程度的植株以及不同品种的关键物种，如 、 和 。总体而言，决定根中真菌群落的最重要因素是植株症状严重程度，而在根际中，植物基因型是决定真菌群落的最重要因素。
