J. Egea, D. Ruiz, and L. Burgos
J. Egea, D. Ruiz, F. Dicenta, and L. Burgos
A. Ruiz*, D.S. Rodriguez, G.A. Picchioni, J.G. Mexal, and T.W. Sammis
Low-cost, sustainable wastewater treatment systems are needed for rapidly-growing communities of the southwestern United States. The objective of this study is to develop a practical management plan for land application of industrial wastewater on native Chihuahuan Desert vegetation. To assess environmental impact and create the management plan, wastewater effluent characteristics, soil physicochemical changes, and mineral uptake of the vegetation were monitored. The effluent was saline, ranging from 2500 to 6000 mg·L-1 of TDS and dominated by Na and Cl. Total N ranged from 10 to 40 mg·L-1. Soils sampled in Dec. 2002 (after 11 months and 64 cm of effluent irrigation) increased in salinity in the top 60 cm from 1.85 to 3.5 dS·m-1, and SAR in the top 30 cm was close to 15, but diminished with depth. Branch samples of the co-dominant perennial shrub vegetation members (Larrea tridentata and Prosopis glandulosa) harvested in July 2002 had elevated Na and Cl concentrations (0.4% to 2.1% of dry weight, respectively). By Oct. 2002, L. tridentata leaves contained comparable Na and Cl concentrations as those of P. glandulosa, yet removed 2 to three times more Na, Cl, and total N per branch, while maintaining their dry mass per branch. This raises the possibility of interspecific variation among the shrub species in salinity stress tolerance and capacity to remove wastewater contaminants. These data will aid in determining total vegetation removal of effluent components, preventing adverse environmental impact to the site, and developing a practical management plan suitable for small communities seeking cost-effective wastewater handling protocols.
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.
Juan J. Ruiz, Belen Pico, Genyi Li, Vincent D'Antonio, Bryce Falk, and Carlos F. Quiros
Resistance to Celery mosaic virus (CeMV) in celery [Apium graveolens L. var. dulce (Mill.) Pers.] is recessive and determined by the single gene, cmv. We report discovery of two polymerase chain reaction-based dominant markers tightly linked to cmv in segregating F2 and BC1 populations. Marker me1em2 is associated to the dominant (susceptibility allele) and the second marker, me8em2, to the recessive (resistance allele). Simultaneous screening for both markers in segregating populations allows for identification of both homozygous and heterozygous genotypes for disease resistance. This marker system can be used for early seedling selection, which will simplify and speed development of celery cultivars resistant to CeMV.