School of Agricultural Engineering, Area of Agroforestry Engineering, University of Seville, Seville, Spain.
Department of Genetics, University of Córdoba, Córdoba, Spain.
Methods Mol Biol. 2021;2309:105-111. doi: 10.1007/978-1-0716-1429-7_9.
Current knowledge on the mechanism of strigolactones (SLs) as signaling molecules during specific interactions in the rhizosphere is mainly related to the control of germination of parasitic weed seeds and hyphal branching of arbuscular mycorrhizal fungi. Thus, the role of plant secreted SLs in regulating the growth and development of root-colonizing fungi still remains controversial. Fusarium oxysporum can sense and respond to extracellular signals through oriented germ tube emergence and redirectioning of hyphal growth toward gradients of nutrients, sex pheromones, or plant root exudates. However, chemoattractant activity of SLs against microorganisms living in the soil has not been tested so far. Here we propose a quantitative chemotropic assay to understand if and how soil fungi could sense gradients of SLs and SLs-like sources. In the example case of F. oxysporum, hyphae of fungal representative mutants preferentially grow toward the synthetic SL analog GR24; and this chemotropic response requires conserved elements of the fungal invasive growth mitogen-activated protein kinase (MAPK) cascade.
目前关于独脚金内酯（SLs）作为根际特定相互作用中信号分子的作用机制的知识，主要与寄生杂草种子萌发和丛枝菌根真菌菌丝分枝的控制有关。因此，植物分泌的 SLs 在调节定殖于根际的真菌的生长和发育中的作用仍然存在争议。尖孢镰刀菌可以通过定向的芽管伸出和菌丝生长向营养物质、性信息素或植物根分泌物梯度的重新定向来感知和响应细胞外信号。然而，到目前为止，还没有测试 SLs 对生活在土壤中的微生物的化感活性。在这里，我们提出了一种定量趋化性测定法，以了解土壤真菌是否以及如何感知 SLs 和 SLs 类似物源的梯度。以尖孢镰刀菌为例，真菌代表性突变体的菌丝优先向合成的 SL 类似物 GR24 生长；并且这种趋化性反应需要真菌侵袭生长丝裂原激活蛋白激酶（MAPK）级联的保守元件。
