Resumen:
Lettuce (Lactuca sativa L.) is extensively grown and is the most widely used
food crop for the called ¿Fourth Range¿ of vegetables. Lettuce exhibits healthy properties
mainly due to the presence of antioxidant compounds (vitamins C and E, carotenoids,
polyphenols) alongside significant fibre content and useful amounts of certain minerals.
Lettuce can establish a mutualistic association with arbuscular mycorrhizal fungi (AMF).
The establishment of the symbiosis involves a continuous cellular and molecular dialogue
between both symbionts, which includes the activation of antioxidant, phenylpropanoid or
carotenoid metabolic pathways. The presence of AMF colonizing roots of greenhouse-grown
lettuces can induce an accumulation of secondary metabolites, vitamins and minerals in
leaves that overcome the dilution effect due to the increased size of mycorrhizal plants.
Therefore, AMF would allow the intake of minerals and compounds with antioxidant
properties to be enhanced without increasing the consumption of lettuce in the diet. In
addition, increased quantities of secondary metabolites may help lettuce plants to
withstand biotic and abiotic stresses. Our review discusses the influence exerted by several
environmental factors and agronomic practices on the ability of AMF for enhancing
the levels of vitamins, nutraceuticals and minerals in leaves of green and red-leaf
types of lettuces.
