No abstract

The aim of this study was to evaluate the effect of eight native consortia of arbuscular mycorrhizal fungi (AMF), a commercial strain and a control without AMF on the growth of Agave inaequidens. Agave seedlings were inoculated and kept under greenhouse conditions for 300 days. At 90, 180 and 270 days after inoculation, the number of leaves and plant height were recorded; at the end of the experiment, fresh and dry weight, head (also known as heart or piña) diameter, leaf area and root length and volume were recorded. The percentage of mycorrhizal colonization, the relative mycorrhizal dependency index and the Dickson index were also calculated. Results showed a growth-promoting effect on agave plants when inoculated with native consortia, namely Barranca de las nueces, El Limón, Agua Dulce and Huizachal, compared to the control. Colonization values were high (45%) and similar to those reported in other studies with agaves. Plants inoculated with the Huichazal consortium obtained the highest Dickson index (9.6). It can be concluded that native consortia are a feasible alternative for use as growth promoters in Agave inaequidens and that they can be a good option as biofertilizer sunder nursery conditions.

Blue agave (Agave tequilana F.A.C. Weber var. Azul) is an important crop for Mexico, from which tequila is made. In 2018 1,138,800 t of agave were produced under aproduction system where the use of agrochemicals has become widespread; in particular, the excessive use of chemical fertilizers generates problems of environmental impact in the producing areas. An alternative to solve this problem is the use of soil microbial resources to reduce this impact. The use of arbuscular mycorrhizal fungi (AMF) as biofertilizers is a functional alternative in other crops that could be implemented in the production of blue agave. The aim of this research was to evaluate the effect of native mycorrhizal consortia isolated from the rhizosphere of A. cupreata from Michoacán on the growth of blue agave. An experiment was conducted under a randomized complete blocks design where eight AMF consortia, a commercial inoculum (Rhizophagus intraradices) and a control (without AMF) were evaluated on A. tequilana seedlings. The experiment was maintained for 300 d under greenhouse conditions and, at the end, growth and microbiological variables were analyzed; in addition, mycorrhizal dependency and the Dickson index were calculated as parameters of plant quality. Significant differences (Tukey, P ≤ 0.05) were found in the growth traits of agave plants when inoculated with AMF consortia compared to control plants. The agave plants inoculated with the native consortium Barranca de las Nueces showed greater growth and Dickson index, with a mycorrhizal colonization of 49 % and a mycorrhization dependency of 62 %, as well as the highest spore density (244 spores 100 g-1 of substrate). Results suggest that AMF could be a biotechnology alternative in the agricultural production process of blue agave.

Mango malformation disease (MMD) caused by Fusarium spp. is an important limiting factor in most production areas worldwide. Fusarium mexicanum and F. pseudocircinatum have been reported as causing MMD in Mexico. These two pathogens also cause a similar disease in Swietenia macrophylla (big-leaf mahogany malformation disease or BLMMD) in central western Mexico, while F. pseudocircinatum was recently reported as causing malformation disease in Tabebuia rosea (rosy trumpet) in the same region. These studies suggest that additional plant species, including weeds, might be hosts of these pathogens. The role that weed hosts might have in the disease cycle is unknown. The objectives of this work were to recover Fusarium isolates from understory vegetation in mango orchards with MMD, identify the Fusarium isolates using DNA sequence data, and determine if F. mexicanum is capable of inducing disease in the weedy legume Senna uniflora (oneleaf senna). Additional objectives in this work were to compare Fusarium isolates recovered from weeds and mango trees in the same orchards, by characterizing their phylogenetic relationships, assessing in vitro production of mycotoxins, and identifying their mating type idiomorph. A total of 59 Fusarium isolates from five species complexes were recovered from apical and lateral buds from four weed species. Two of the species within the F. fujikuroi species complex are known to cause MMD in Mexico. Trichothecene production was detected in five isolates, including F. sulawense and F. irregulare in the F. incarnatum-equiseti species complex and F. boothii in the F. sambucinum species complex. Both mating types were present among mango and weed isolates. This is the first report of herbaceous hosts harboring Fusarium species that cause mango malformation in Mexico. The information provided should prove valuable for further study of the epidemiological role of weeds in MMD, and help manage the disease.

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