We have identified a plasma membrane Na + /H + antiporter gene from tomato (Solanum lycopersicum), SlSOS1, and used heterologous expression in yeast to confirm that SlSOS1 was the functional homolog of AtSOS1. Using posttranscriptional gene silencing, we evaluated the role played by SlSOS1 in long-distance Na + transport and salt tolerance of tomato. Tomato was used because of its anatomical structure, more complex than that of Arabidopsis, and its agricultural significance. Transgenic tomato plants with reduced expression of SlSOS1 exhibited reduced growth rate compared to wild-type (WT) plants in saline conditions. This sensitivity correlated with higher accumulation of Na + in leaves and roots, but lower contents in stems of silenced plants under salt stress. Differential distribution of Na + and lower net Na + flux were observed in the xylem sap in the suppressed plants. In addition, K + concentration was lower in roots of silenced plants than in WT. Our results demonstrate that SlSOS1 antiporter is not only essential in maintaining ion homeostasis under salinity, but also critical for the partitioning of Na + between plant organs. The ability of tomato plants to retain Na + in the stems, thus preventing Na + from reaching the photosynthetic tissues, is largely dependent on the function of SlSOS1.

The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na

The effect of ozone treatment on the postharvest quality of strawberry was evaluated. Strawberry fruits (Fragaria x ananassa Duch. cv. Camarosa) were stored at 2 degrees C in an atmosphere containing ozone (0.35 ppm). After 3 days at 2 degrees C, fruits were moved to 20 degrees C to mimic retail conditions (shelf life). The changes in several quality parameters such as fungal decay, color, sugar and acids distribution, and aroma were evaluated during the strawberries' shelf life. Ozone treatment was ineffective in preventing fungal decay in strawberries after 4 days at 20 degrees C. Significant differences in sugars and ascorbic acid content were found in ozone-treated strawberries. At the end of cold storage, the vitamin C content of ozonated strawberries was 3 times that of control fruits. A detrimental effect of ozone treatment on strawberry aroma was observed, with a 40% reduced emission of volatile esters in ozonated fruits.

An analytical procedure to determine major sugars and organic acids, including vitamin C, in fruits was developed using a C18 Sep-Pak cleanup process and an ion exclusion HPLC column. Dual UV monitoring and refractive index were performed for detection. To attain optimal separation and quantitation, 0.0085N H2SO4 was used as the mobile phase and the column temperature was maintained at 23 °C. This procedure was compared to others for the individual quantitation of sugars, organic acids, and vitamin C. Recovery and reproducibility of this analytical procedure were quite acceptable for strawberry and four other common fruits, allowing the analysis of all the components using a single-injection HPLC analysis in <22 min. Keywords: Simultaneous analysis; high-performance liquid chromatography; sugars; organic acids; vitamin C; strawberry; fruits