Flavonoids promote Rhizophagus irregularis spore germination and tomato root colonization: A target for sustainable agriculture

Abstract

The use of arbuscular mycorrhizal (AM) fungi has great potential, being used as biostimulants, biofertilizers and bioprotection agents in agricultural and natural ecosystems. However, the application of AM fungal inoculants is still challenging due to the variability of results when applied in production systems. This variability is partly due to differences in symbiosis establishment. Reducing such variability and promoting symbiosis establishment is essential to improve the efficiency of the inoculants. In addition to strigolactones, flavonoids have been proposed to participate in the pre-symbiotic plant-AM fungus communication in the rhizosphere, although their role is still unclear. Here, we studied the specific function of flavonoids as signaling molecules in AM symbiosis. For that, both in vitro and in planta approaches were used to test the stimulatory effect of an array of different subclasses of flavonoids on Rhizophagus irregularis spore germination and symbiosis establishment, using physiological doses of the compounds. We show that the flavone chrysin and the flavonols quercetin and rutin were able to promote spore germination and root colonization at low doses, confirming their role as pre-symbiotic signaling molecules in AM symbiosis. The results pave the way to use these flavonoids in the formulation of AM fungal-based products to promote the symbiosis. This can improve the efficiency of commercial inoculants, and therefore, help to implement their use in sustainable agriculture.

Mycorrhiza‐induced resistance in citrus against Tetranychus urticae is plant species dependent and inversely correlated to basal immunity

“…In this study, repeated treatments with the C4H inhibitor PIP over a period of a month reduced root colonization by R. irregularis by 50%, although it did not fully abolish symbiosis. Hence, phenylpropanoids and flavonoid derivatives are relevant for symbiosis in citrus, as previously shown in other crops 85,87 . Furthermore, we confirmed that C4H activity is essential for MIR in citrus, because a single treatment with PIP 1 day before infestation abolished MIR.…”

Investigation of pectin deficiency in modulating the bioflavonoid profile of orange processing waste: A sustainable valorization of industrial waste

“…These compounds can serve as natural agents to strengthen plant resistance, reduce the need for chemicals and improve crop quality. In addition, studies have shown that flavonoids can play a fundamental role in promoting plant growth, stimulating nutrient absorption and optimizing metabolic processes ( Lidoy et al (2023) ). Flavonoids show intriguing potential for the development of more sustainable phytosanitary products, as certain varieties have demonstrated pesticidal activity.…”

Tap into non-symbiotic carbon? Exogenous myristate fuels the growth of symbiotic arbuscular mycorrhizal fungi but disrupts their carbon‒phosphorus exchange with host plants

“…Notably, the signaling role of myristate has also been found in several soil-borne bacteria (Fernández-Piñar et al ., 2012; Liu et al ., 2024), implying its universal role in regulating the soil microbiome. AMF signal molecules such as strigolactones and flavonoids increase AMF colonization by promoting spore germination, and hyphal growth and branching (Mori et al ., 2016; Lidoy et al ., 2023; Yu et al ., 2022); and palmitoleic acid even stimulates asymbiotic AMF to generate infection-competent, albeit morphologically and functionally incomplete, secondary spores, without increasing AMF biomass (Sugiura et al ., 2020). Unlike those signaling molecules, myristate enhanced both intraradical and extraradical fungal biomasses in our study, likely due to its dual role as a signaling molecule and a C source for AMF.…”