Strategies to Modulate Specialized Metabolism in Mediterranean Crops: From Molecular Aspects to Field.

Plant specialized metabolites (SMs) play an important role in the interaction with the environment and are part of the plant defense response. These natural products are volatile, semi-volatile and non-volatile compounds produced from common building blocks deriving from primary metabolic pathways and rapidly evolved to allow a better adaptation of plants to environmental cues. Specialized metabolites include terpenes, flavonoids, alkaloids, glucosinolates, tannins, resins, etc.

Appressoria and phosphorus fluxes in mycorrhizal plants: connections between soil- and plant-based hyphae.

Arbuscular mycorrhizal fungi (AMF) live in symbiosis with plant roots, facilitating mineral nutrient transfer from soil to hosts through large networks of extraradical hyphae. Limited data are available on the fungal structures (appressoria) connecting soil- to root-based mycelium, in relation to plant nutrition. Two in vivo systems were set up using three AMF, Funneliformis mosseae, Funneliformis coronatus and Rhizoglomus irregulare, grown in symbiosis with Cichorium intybus.

Mycorrhizal networks facilitate the colonization of legume roots by a symbiotic nitrogen-fixing bacterium.

Arbuscular mycorrhizal fungi (AMF) absorb and translocate nutrients from soil to their host plants by means of a wide network of extraradical mycelium (ERM). Here, we assessed whether nitrogen-fixing rhizobia can be transferred to the host legume Glycine max by ERM produced by Glomus formosanum isolate CNPAB020 colonizing the grass Urochloa decumbens. An H-bridge experimental system was developed to evaluate the migration of ERM and of the GFP-tagged Bradyrhizobium diazoefficiens USDA 110 strain across an air gap compartment.

Two herbicides, two fungicides and spore-associated bacteria affect Funneliformis mosseae extraradical mycelium structural traits and viability.

The extraradical mycelium (ERM) produced by arbuscular mycorrhizal fungi is fundamental for the maintenance of biological fertility in agricultural soils, representing an important inoculum source, together with spores and mycorrhizal root fragments. Its viability and structural traits, such as density, extent and interconnectedness, which are positively correlated with the growth and nutrition of host plants, may be affected by different agronomic practices, including the use of pesticides and by different mycorrhizospheric communities. This work, carried out using a whole-plant experimental model system, showed that structural traits of ERM, such as length and density, were strongly decreased by the herbicides dicamba and glufosinolate and the fungicides benomyl and fenhexamid, while anastomosis frequency and hyphal branching were differentially modulated by singly inoculated mycorrhizospheric bacteria, depending on their identity.

Lifespan and functionality of mycorrhizal fungal mycelium are uncoupled from host plant lifespan.

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts, living in associations with the roots of most land plants. AMF produce wide networks of extraradical mycelium (ERM) of indeterminate length, spreading from host roots into the surrounding soil and establishing belowground interconnections among plants belonging to the same or to different taxa. Whether their lifespan and functionality are limited by host plant viability or can be extended beyond this limit is unknown.

Divergence of Funneliformis mosseae populations over 20 years of laboratory cultivation, as revealed by vegetative incompatibility and molecular analysis.

Arbuscular mycorrhizal fungi (AMF) are widespread, important plant symbionts. They absorb and translocate mineral nutrients from the soil to host plants through an extensive extraradical mycelium, consisting of indefinitely large networks of nonseptate, multinucleated hyphae which may be interconnected by hyphal fusions (anastomoses). This work investigated whether different lineages of the same isolate may lose the ability to establish successful anastomoses, becoming vegetatively incompatible, when grown separately.