Souza Ricardo M, Oliveira Denilson F, Gomes Vicente M, Viana Abraão J S, Silva Geraldo H, Machado Alan R T
Departamento de Entomologia e Fitopatologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Brazil.
Departamento de Química, Universidade Federal de Lavras, Lavras, Brazil.
J Nematol. 2023 Dec 31;55(1):20230055. doi: 10.2478/jofnem-2023-0055. eCollection 2023 Feb.
Despite the worldwide importance of disease complexes involving root-feeding nematodes and soilborne fungi, there have been few in-depth studies on how these organisms interact at the molecular level. Previous studies of guava decline have shown that root exudates from -parasitized guava plants (NP plants), but not from nematode-free plants (NF plants), enable the fungus to rot guava roots, leading to plant death. To further characterize this interaction, NP and NF root exudates were lyophilized; extracted with distinct solvents; quantified regarding amino acids, soluble carbohydrates, sucrose, phenols, and alkaloids; and submitted to a bioassay to determine their ability to enable to rot the guava seedlings' roots. NP root exudates were richer than NF root exudates in amino acids, carbohydrates, and sucrose. Only the fractions NP-03 and NP-04 enabled fungal root rotting. NP-03 was then sequentially fractionated through chromatographic silica columns. At each step, the main fractions were reassessed in bioassay. The final fraction that enabled fungal root rotting was submitted to analysis using high performance liquid chromatography, nuclear magnetic resonance, mass spectrometry, energy-dispersive X-ray fluorescence, and computational calculations, leading to the identification of 1,5-dinitrobiuret as the predominant substance. In conclusion, parasitism by causes an enrichment of guava root exudates that likely favors microorganisms capable of producing 1,5-dinitrobiuret in the rhizosphere. The accumulation of biuret, a known phytotoxic substance, possibly hampers root physiology and the innate immunity of guava to .
尽管涉及根际取食线虫和土传真菌的病害复合体在全球具有重要意义，但关于这些生物体在分子水平上如何相互作用的深入研究却很少。先前对番石榴衰退病的研究表明，被寄生的番石榴植株（NP植株）的根系分泌物能使真菌腐烂番石榴根，导致植株死亡，而未受线虫侵染的植株（NF植株）的根系分泌物则不能。为了进一步表征这种相互作用，将NP和NF根系分泌物冻干；用不同溶剂提取；对氨基酸、可溶性碳水化合物、蔗糖、酚类和生物碱进行定量；并进行生物测定以确定它们使真菌腐烂番石榴幼苗根系的能力。NP根系分泌物中的氨基酸、碳水化合物和蔗糖比NF根系分泌物更丰富。只有NP - 03和NP - 04组分能使真菌根系腐烂。然后通过色谱硅胶柱对NP - 03进行连续分级分离。在每一步，主要组分都在生物测定中重新评估。使真菌根系腐烂的最终组分通过高效液相色谱、核磁共振、质谱、能量色散X射线荧光分析和计算进行分析，从而鉴定出1,5 - 二硝基缩二脲为主要物质。总之，[线虫名称未给出]的寄生导致番石榴根系分泌物富集，这可能有利于根际中能够产生1,5 - 二硝基缩二脲的微生物。已知的植物毒性物质缩二脲的积累可能会阻碍番石榴根系生理和对[线虫名称未给出]的固有免疫力。
