Quercetin and 1-methyl-2-oxindole mimic root signaling that promotes spore germination and mycelial growth of Gigaspora margarita

Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs, and the difficulty of growing them in asymbiotic or monoxenic (AMF + root) conditions limits research and their large-scale production as biofertilizer. We hypothesized that a combination of flavanols and strigolactones can mimic complex root signaling during the presymbiotic stages of AMF. We evaluated the germination, mycelial growth, branching, and auxiliary cell clusters formation by Gigaspora margarita during the presymbiotic stage in the presence (or absence) of transformed Cichorium intybus roots in basal culture medium enriched with glucose, a flavonol (quercetin or biochanin A) and a strigolactone analogue (1-Methyl-2-oxindole or indole propionic acid). With quercetin (5 µM), methyl oxindole (2.5 nM), and glucose (8.2 g/L) in the absence of roots, the presymbiotic mycelium of G. margarita grew without cytoplasmic retraction and produced auxiliary cells over 71 days similar to presymbiotic mycelium in the presence of roots but without glucose, strigolactones, and flavonols. Our results indicate that glucose and a specific combination of certain concentrations of a flavonol and a strigolactone might be used in asymbiotic or monoxenic liquid or semisolid cultures to stimulate AMF inoculant bioprocesses.

Bioactive constituents from transformed root cultures of Nepeta teydea

A phytochemical study of an extract from transformed root cultures of Nepeta teydea, induced by Agrobacterium rhizogenes, led to the isolation of the following new compounds: the sesquiterpene (-)-cinalbicol, the diterpene teydeadione (6,11,14-trihydroxy-12-methoxy-abieta-5,8,11,13,15-penten-7-one), a degraded C23-triterpene (teydealdehyde) and three fatty acid esters of lanosta-7,24-dien-3β-ol. The propyl ester of rosmarinic acid was also isolated for the first time from a natural source. In addition, two dehydroabietane diterpenes, eight triterpenes and eighteen known phenolic compounds were obtained. The antifeedant, cytotoxic and phytotoxic activities of the isolated compounds have also been investigated.