Arbuscular Mycorrhizal Fungi Associated with Maize (Zea mays L.) in the Formation and Stability of Aggregates in Two Types of Soil.

Knowledge of native Arbuscular Mycorrhizal Fungi (AMF) and their relationship with the edaphic characteristics where they live is important to establish the influence of allochthonous AMF, which were inoculated, on the development and stability of soil aggregates. The objectives of this research were to know the composition of native AMF species from two contrasting soils, and to establish the development and stability of aggregates in those soils with corn plants after inoculating them with allochthonous AMF. The experiment had three factors: Soil (two levels [S1 and S2]), HMA (three levels: without application [A0], with the application of Claroideoglomus claroideum [A1] and with the application of a consortium [A2]) and Fertilization (two levels (without fertilization [f0] and with fertilization [f1])). Twelve treatments were generated, with five replicates (60 experimental units [EU]). The EU consisted of a pot with a corn plant and the distribution was completely random. The results demonstrated that the Typic Ustifluvent presented nine species of native AMF, while the Typic Dystrustert had three; the native AMF in each soil influenced the activity of allochthonous AMF, such as their colonization and sporulation. Likewise, differences were found in the stability of macro-sized aggregates (0.5 to 2.0 mm).

Physiological Responses of Agave maximiliana to Inoculation with Autochthonous and Allochthonous Arbuscular Mycorrhizal Fungi.

The benefits of mycorrhizal interactions are only known in 8 of 210 recognized Agave taxa. We evaluated the effects of autochthonous and allochthonous arbuscular mycorrhizal fungi (AMF) on growth and nutrient assimilation in Agave maximiliana. The autochthonous consortium (Cn) of eight species was propagated from the rhizospheric soil of A. maximiliana, while Claroideoglomus claroideum (Cc) and Claroideoglomus etunicatum (Ce) were employed as allochthonous AMF. Six treatments were included in the study: Cn, Ce, Cc, Ce + Cc, Tf (fertilized control), and Tn (non-fertilized control, not inoculated). Mycorrhizal colonization increased over time, and the colonization percentages produced by Cn and the allochthonous AMF, both alone and mixed together, were equal at 6, 12, and 18 months. Height increased steadily and was higher in AMF-treated plants from seven months onward. Growth indicators of AMF-treated and AMF-free plants were equal at 6 months, but the beneficial effects of allochthonous and autochthonous AMF were evident in all growth indicators at 18 months and in sugar and mineral (P, K, Ca, Mg, and Fe) content. Arbuscular mycorrhizal fungi significantly improved all growth parameters of A. maximiliana regardless of the origin of the inoculums. This is the first study to report the positive effects of AMF colonization in A. maximiliana.

Expression of the 1-SST and 1-FFT genes and consequent fructan accumulation in Agave tequilana and A. inaequidens is differentially induced by diverse (a)biotic-stress related elicitors.

The expression of genes coding for sucrose:sucrose 1-fructosyltransferase (1-SST; EC 2.4.1.99) and fructan:fructan 1-fructosyltransferase (1-FFT; EC 2.4.1.100), both fructan biosynthesizing enzymes, characterization by TLC and HPAEC-PAD, as well as the quantification of the fructo-oligosaccharides (FOS) accumulating in response to the exogenous application of sucrose, kinetin (cytokinin) or other plant hormones associated with (a)biotic stress responses were determined in two Agave species grown in vitro, domesticated Agave tequilana var. azul and wild A. inaequidens. It was found that elicitors such as salicylic acid (SA), and jasmonic acid methyl ester (MeJA) had the strongest effect on fructo-oligosaccharide (FOS) accumulation. The exogenous application of 1mM SA induced a 36-fold accumulation of FOS of various degrees of polymerization (DP) in stems of A. tequilana. Other treatments, such as 50mM abscisic acid (ABA), 8% Sucrose (Suc), and 1.0 mg L(-1) kinetin (KIN) also led to a significant accumulation of low and high DP FOS in this species. Conversely, treatment with 200 µM MeJA, which was toxic to A. tequilana, induced an 85-fold accumulation of FOS in the stems of A. inaequidens. Significant FOS accumulation in this species also occurred in response to treatments with 1mM SA, 8% Suc, and 10% polyethylene glycol (PEG). Maximum yields of 13.6 and 8.9 mg FOS per g FW were obtained in stems of A. tequilana and A. inaequidens, respectively. FOS accumulation in the above treatments was tightly associated with increased expression levels of either the 1-FFT or the 1-SST gene in tissues of both Agave species.

Effect of the temperature on the spray drying of Roselle extracts (Hibiscus sabdariffa L.).

The effect of the drying temperature on the volatile components and sensory acceptance of the Roselle (Hibiscus sabdariffa) extract in powder was investigated. The Roselle extraction was carried out by maceration with 7 L of 30% ethanol (v/v), 560 g of fresh Roselle calyces for 168 h. The Roselle extracts were spray dried at different temperatures 150, 160, 170, 180, 190, 200 and 210 degrees C, giving different outlet values about yield and final moisture. The volatile compounds in Roselle extract and dried samples were performed using needles of solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS HP-5890). Twenty volatile compounds were identified in the extracts among them terpenoids, esters, hydrocarbons and aldehydes. Fourteen volatile compounds were identified in the powder sample, but only ten were present in the Roselle extract. This indicates that some compounds were lost and some others were generated due to a degradation process. An acceptability sensory analysis showed that the best powder sample was the Roselle extract dehydrated using temperature between 190 degrees C and 200 degrees C (p<0.05). There was not statistically significant difference in the pH of Roselle extracts ranging from 3.4 to 3.9. It was concluded that the spray drying temperature of the Roselle extracts has an effect on the volatile compounds losses.