Li Yonghua, Li Xinghong, Zhang Wei, Zhang Jiao, Wang Hui, Peng Junbo, Wang Xuncheng, Yan Jiye
Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China.
College of Plant Protection, Hebei Agricultural University, Baoding, 071000, China.
Environ Microbiome. 2023 Apr 3;18(1):29. doi: 10.1186/s40793-023-00490-0.
Grapevine trunk diseases (GTDs) are disease complexes that are major threats to viticulture in most grapevine growing regions. The microbiomes colonizing plant belowground components form complex associations with plants, play important roles in promoting plant productivity and health in natural environments, and may be related to GTD development. To investigate associations between belowground fungal communities and GTD symptomatic or asymptomatic grapevines, fungal communities associated with three soil-plant compartments (bulk soils, rhizospheres, and roots) were characterized by ITS high-throughput amplicon sequencing across two years.
The fungal community diversity and composition differs according to the soil-plant compartment type (PERMANOVA, p < 0.001, 12.04% of variation explained) and sampling year (PERMANOVA, p < 0.001, 8.83%), whereas GTD symptomatology exhibited a weaker, but still significant association (PERMANOVA, p < 0.001, 1.29%). The effects of the latter were particularly prominent in root and rhizosphere community comparisons. Many GTD-associated pathogens were detected, but their relative abundances were not correlated (or were negatively correlated) to symptomatology. Fusarium spp., were enriched in symptomatic roots and rhizospheres compared to asymptomatic counterparts, suggesting that their abundances were positively correlated with symptomatic vines. Inoculation tests revealed that Fusarium isolates, similar to Dactylonectria macrodidyma, a pathogen associated with black foot disease, caused dark brown necrotic spots on stems in addition to root rot, which blackened lateral roots. Disease indices were higher with co-inoculation than single inoculation with a Fusarium isolate or D. macrodidyma, suggesting that Fusarium spp. can exacerbate disease severity when inoculated with other known GTD-associated pathogens.
The belowground fungal microbiota of grapevines varied from soil-plant compartments, the years and whether showed GTD symptoms. The GTDs symptoms were related to the enrichment of Fusarium spp. rather than the relative abundances of GTD pathogens. These results demonstrate the effects of fungal microbiota of roots and rhizospheres on GTDs, while providing new insights into opportunistic pathogenesis of GTDs and potential control practices.
葡萄树干病害（GTDs）是一类病害复合体，对大多数葡萄种植区的葡萄栽培构成重大威胁。定殖于植物地下部分的微生物群落与植物形成复杂的关联，在自然环境中对促进植物生产力和健康发挥重要作用，并且可能与GTDs的发生发展有关。为了研究地下真菌群落与出现或未出现GTD症状的葡萄树之间的关联，通过两年的ITS高通量扩增子测序对与三个土壤-植物组分（大田土壤、根际和根系）相关的真菌群落进行了特征分析。
真菌群落的多样性和组成因土壤-植物组分类型（PERMANOVA，p < 0.001，解释变异的12.04%）和采样年份（PERMANOVA，p < 0.001，8.83%）而异，而GTD症状表现出较弱但仍显著的关联（PERMANOVA，p < 0.001，1.29%）。后者的影响在根系和根际群落比较中尤为突出。检测到许多与GTD相关的病原体，但其相对丰度与症状无关（或呈负相关）。与无症状的根系和根际相比，镰刀菌属在出现症状的根系和根际中富集，这表明它们的丰度与出现症状的葡萄树呈正相关。接种试验表明，类似于与黑脚病相关病原体大茎点霉的镰刀菌分离株，除了导致根腐病使侧根变黑外，还会在茎上引起深褐色坏死斑。联合接种的病害指数高于单独接种镰刀菌分离株或大茎点霉，这表明镰刀菌属与其他已知的与GTD相关的病原体共同接种时会加剧病害严重程度。
葡萄树的地下真菌微生物群因土壤-植物组分、年份以及是否表现出GTD症状而有所不同。GTD症状与镰刀菌属的富集有关，而不是与GTD病原体的相对丰度有关。这些结果证明了根系和根际真菌微生物群对GTDs的影响，同时为GTDs的机会性发病机制和潜在防治措施提供了新的见解。
