Phenylpropanoids Are Connected to Cell Wall Fortification and Stress Tolerance in Avocado Somatic Embryogenesis.

Somatic embryogenesis (SE) is a valuable model for understanding the mechanism of plant embryogenesis and a tool for the mass production of plants. However, establishing SE in avocado has been complicated due to the very low efficiency of embryo induction and plant regeneration. To understand the molecular foundation of the SE induction and development in avocado, we compared embryogenic (EC) and non-embryogenic (NEC) cultures of two avocado varieties using proteomic and metabolomic approaches. Although Criollo and Hass EC exhibited similarities in the proteome and metabolome profile, in general, we observed a more active phenylpropanoid pathway in EC than NEC. This pathway is associated with the tolerance of stress responses, probably through the reinforcement of the cell wall and flavonoid production. We could corroborate that particular polyphenolics compounds, including p-coumaric acid and t-ferulic acid, stimulated the production of somatic embryos in avocado. Exogen phenolic compounds were associated with the modification of the content of endogenous polyphenolic and the induction of the production of the putative auxin-a, adenosine, cellulose and 1,26-hexacosanediol-diferulate. We suggest that in EC of avocado, there is an enhanced phenylpropanoid metabolism for the production of the building blocks of lignin and flavonoid compounds having a role in cell wall reinforcement for tolerating stress response. Data are available at ProteomeXchange with the identifier PXD019705.

Chromium and Lead adsorption by avocado seed biomass study through the use of Total Reflection X-Ray Fluorescence analysis.

Adsorption is an effective method for the treatment of wastewater containing low concentrations of heavy metals. This kind of metals such as Chromium and Lead could affect health and the ecosystem. In this work, biomass of avocado seed was used as adsorbent. It was tested as adsorbent in natural form (NB), as a chemically activated (AB) form and as activated carbon (AC). Batch reactors were used to investigate the adsorbent efficiency. Concentration of metal ions was measured using Total Reflection X-Ray Fluorescence. Operational conditions influencing adsorption, such as: pH, adsorbent dose, initial concentration and contact time, were measured and controlled. The 80% of adsorption was reached, at pH: 5 and 25 °C, when were used 50 mL of: a 20 mg L-1 of Cr (VI) solution with a dose of 1.25 g of NB, a 30 mg L-1 of Pb (II) solution with a dose of 0.15 g of NB, a 50 mg L-1 Pb (II) solution with a dose of 0.15 g of AB, a 30 mg L-1 Cr (VI) solution with a dose of 0.35 g of AB, a 30 mg L-1 of both metals, with a dose of 0.15 g of AC for Pb (II) and 0.7 g of AC for Cr (VI). In all cases, the pH value before and during the experiments remained constant, indicating the lack of acid/base reactions during the processes. The Langmuir adsorption isotherm model best fitted to the experimental data. The experimental results from kinetic studies best correlated using the pseudo-second order model. An increase in the remotion of both ions (Pb (II) and Cr (VI)), was observed when comparing the results obtained using the activated biomass. However, considering the loss of biomass that the pre-treatment causes, the remotion per gram of initial biomass does not vary significantly.

Water relations in culture media influence maturation of avocado somatic embryos.

Application of transformation and other biotechnological tools in avocado (Persea americana Mill.) is hampered by difficulties in obtaining mature somatic embryos capable of germination at an acceptable rate. In this work, we evaluated the effect of different compounds affecting medium water relations on maturation of avocado somatic embryos. Culture media were characterized with respect to gel strength, water potential and osmotic potential. Improved production of mature somatic embryos was achieved with gelling agent concentrations higher than those considered standard. The osmotic agents such as sorbitol and PEG did not have positive effects on embryo maturation. The number of w-o mature somatic embryos per culture was positively correlated with medium gel strength. Gel strength was significantly affected by gelling agent type as well as by gelling agent and PEG concentration. Medium water potential was influenced by sorbitol concentration; incorporation of PEG to a culture medium did not affect medium water potential. The highest maturation results were achieved on a medium gelled with 10 gl(-1) agar. Moreover, these somatic embryos had improved germination rates. These results corroborate the role of water restriction as a key factor controlling maturation of somatic embryos.

The role of the embryo and ethylene in avocado fruit mesocarp discoloration.

Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 degrees C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.

Trypanocidal constituents in plants 5. Evaluation of some Mexican plants for their trypanocidal activity and active constituents in the seeds of Persea americana.

Crude extracts of Mexican medicinal plants were screened for trypanocidal activity against Trypanosoma cruzi, which is the etiological agent for Chagas' disease, one of the most serious protozoan diseases in Latin America. There were 71 kinds of methanolic and other organic extracts from 65 plants, which were newly examined by a preliminary screening test to observe immobilization of epimastigotes and trypomastigotes of T. cruzi in vitro. The MeOH extract of seeds of Persea americana (avocado) showed moderate activity against epimastigotes. In order to identify the principal compounds for the activity, the MeOH extract was subjected to bioassay-guided fractionation. From the active fractions, six 1,2,4-trihydroxyheptadecane derivatives and two 1,2,4-trihydroxynonadecane derivatives including a new one were isolated. These compounds showed moderate activity against epimastigotes and trypomastigotes.