Identifying volatile and non-volatile organic compounds to discriminate cultivar, growth location, and stage of ripening in olive fruits and oils.

BACKGROUND: There is increasing consumer demand for olive oil to be traceable. However, genotype, environmental factors, and stage of maturity, all affect the flavor and composition of both the olives and olive oil. Few studies have included all three variables. Key metabolites include lipids, phenolics, and a wide range of volatile organic compounds (VOCs), which provide the olives and oil with their characteristic flavor. Here we aim to identify markers that are able to discriminate between cultivars, that can identify growth location, and can discriminate stages of fruit maturity. 'Nocellara messinese' and 'Carolea' olive fruits were grown at three locations differing in altitude in Calabria, Italy, and harvested at three stages of maturity. Oil was analyzed from the two most mature stages. RESULTS: Nine and 20 characters discriminated all fruit and oil samples respectively, and relative abundance of two fatty acids distinguished all oils. Whole VOC profiles discriminated among the least mature olives, and oil VOC profiles discriminated location and cultivar at both stages. Three VOCs putatively identified as hexanal, methyl acetate, and 3-hexen-1-ol differentiated all samples of oils from the most mature fruit stage. CONCLUSION: The results confirm that interactions of location, cultivar and fruit maturity stage are critical for the overall pattern of aroma compounds, and identify potential markers of commercial relevance. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Altitude-mediated soil properties, not geography or climatic distance, explain the distribution of a tropical endemic herb.

Understanding the ecological processes that govern species' range margins is a fundamental question in ecology with practical implications in conservation biology. The center-periphery hypothesis predicts that organisms have higher abundance at the center of their geographic range. However, most tests of this hypothesis often used raster data, assuming that climatic conditions are consistent across one square km. This assumption is not always justified, particularly for mountainous species for which climatic conditions can vary widely across a small spatial scale. Previous studies rarely evenly sample occurrence data across the species' distribution. In this study, we sampled an endemic perennial herb, Thunbergia atacorensis (Acanthanceae), throughout its range in West Africa using 54 plots and collected data on (a)biotic variables, the species density, leaf mass per area, and basal diameter. We built a structural equation model to test the direct and indirect effects of distance from geographic and climatic niche centers, and altitude on Thunbergia density as mediated by abiotic and biotic factors, population demographic structure, and individual size. Contrary to the prediction of the center-periphery hypothesis, we found no significant effect of distance from geographic or climatic niche centers on plant density. This indicates that even the climatic center does not necessarily have optimal ecological conditions. In contrast, plant density varied with altitudinal gradient, but this was mediated by the effect of soil nitrogen and potassium which had positive effect on plant size. Surprisingly, we found no direct or mediating effect of interspecific competition on plant density. Altogether, our results highlight the role of geography, climatic, and ecological mismatch in predicting species distribution. Our study highlights that where altitudinal gradient is strong local-scale heterogeneity in abiotic factors can play important role in shaping species range limits.

Ribulose-1,5-bis-phosphate carboxylase activity in altitudinal populations of Espeletia schultzii Wedd.

The ribulose-1,5-bis-phosphate (RBPC) 14CO2 fixation rate was measured at four different temperatures, 5°, 15°, 25° and 35° C, in three populations of Espeletia schultzii at different altitudes, 3100, 3550 and 4200 ma.s.l. The fixation rate increased with temperature increase in the populations studied. The population at 4200 m showed the higher rate at any temperature, followed by those at 3550 and 3100 m. The Km(CO2) increased with temperature increase, but the values were similar among populations. The V max values increased with temperature and were higher for the 4200-m population. These results suggest that the RBPC enzyme is more activated in the highland population and that the enzyme kinetics are not similar among populations.