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David Ruiz, Manuel Rubio, Pedro Martínez-Gómez, Jesús López-Alcolea, Federico Dicenta, Encarna Ortega, María Dolores Nortes, Antonio Molina, Antonio Molina Jr., and Jose Egea

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José Egea, Manuel Rubio, José A. Campoy, Federico Dicenta, Encarna Ortega, María D. Nortes, Pedro Martínez-Gómez, Antonio Molina, Antonio Molina Jr, and David Ruiz

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Teresa Muñoz, Jesús Ruiz-Cabello, Antonio D. Molina-García, María I. Escribano, and Carmen Merodio

Phophorous nuclear magnetic resonance (31P-NMR) spectroscopy was used to study the vacuolar and cytoplasmic pH and the inorganic phosphate (Pi) pool distribution in `Fino de Jete' cherimoya (Annona cherimola Mill.) fruit stored at a chilling temperature (6 °C). Fruit stored at the ripening temperature (20 °C) for 3 days were used as a control. 31P-NMR results confirmed that 6 °C storage caused cytoplasmic acidosis (a decrease of 0.72 ± 0.08 pH units) and a notable increase in the amount of Pi in the cytoplasm. Spectra of perchloric acid extracts also revealed that storage at 6 °C was associated with an increase in the total amount of Pi and phosphorylated metabolites. Moreover, perfusion experiments with a phosphate medium confirmed the preferential accumulation of Pi in the cytoplasm in chilled tissues. Specific activation of phosphoenolpyruvate carboxylase (PEPC) (32.1 ± 1.7 μmol·min-1·mg-1) was observed in those fruit. In chilled fruit the amount of ADP was held at steady-state levels and ATP levels increased, contrary to observations for ripe fruit, where the pool of total nucleotides decreased beyond the point of NMR detection. Fruit stored at 6 °C exhibited a low respiration rate, but metabolism was not arrested and an increase in total soluble solid contents was also observed.

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Carlos Alberto Lecona-Guzmán, Sheila Reyes-Zambrano, Felipe Alonso Barredo-Pool, Miguel Abud-Archila, Joaquín Adolfo Montes-Molina, Reiner Rincón-Rosales, and Federico Antonio Gutierrez-Miceli

Factors such as slow growth, low rates of sexual and asexual reproduction, and viability of seeds among others limit the massive propagation of Agave americana L. by conventional methods. In this study, callus induction and shoot proliferation was determined in A. americana using Murashige and Skoog (MS) medium supplemented with dicholorophenoxyacetic acid (2,4-D) and 6-benzyl adenine (BA). Meristematic tissue was used as the explants, and were placed on MS medium supplemented with 30.0 g·L−1 sucrose with 0.11, 0.18, or 0.45 μm 2,4-D and 11.0, 22.0, 38.2, 44.0, 58.7, or 73.3 μm BA. Treatments were implemented according to factorial experimental design 3 × 6. After 1 month, the number of explants with callus was determined, whereas the numbers of shoots per explant were monitored after 4, 16, 20, and 36 weeks. The maximum percent of explants with callus was obtained with 0.11 μm 2,4-D and 58.7 and 73.3 μm BA, whereas the maximum numbers of shoots per explant (71) were obtained with 0.11 μm 2,4-D and 73.3 μm BA. The effect of different concentrations of indolebutyric acid (IBA) in the rooting of shoots was evaluated. There were no significant effects of IBA on the number of roots, root length, and axillary roots. Plantlets were acclimatized in the glasshouse and they did not show any phenotypic alteration. This is a highly efficient protocol for the in vitro propagation of A. americana via indirect organogenesis.