Biofertilization of micropropagated Agave tequilana: Effect on plant growth and production of hydrolytic enzymes

Three beneficial bacterial strains [Gluconoacetobacter diazotrophicus (Pal5), the diazotrophs (11B) and Pachaz (008)] and an arbuscular mycorrhizal fungus [Glomus intraradices (AMF)] were evaluated for their ability to enhance plant growth and the production of hydrolytic enzymes in micropropagated Agave tequilana Weber var. Blue. Results show that the growth of the agave plants and the production of hydrolytic enzymes in their roots were influenced by the presence of these microorganisms. AMF + 11B treatment induced the greatest fresh weight, showing significant differences with respect to other combinations. Microscopic analysis showed dense root colonization in the AMF treated plants. Pal 5 treatment produced taller plants, indicating a better plant nitrogen nutrition and possibly phytohormone production by Gluconoacetobacter. Treatment Pachaz 008 presented the highest values of the most important agronomic variables, such as the diameter of the pseudo-stem. On another hand, differential catalytic activities of the enzymes beta-glucosidase, cellobiohydrolase and endo-1,4-beta-D-glucanase were detected in inoculated roots in comparison to the un-inoculated control. We offer explanations about those results based on nutritional and hormonal relationships between the microorganisms and the agave plantlets, as well as on the microbial mechanism to colonize the agave roots.