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  • Author or Editor: Joyce Chen x
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Cucumber (Cucumis sativus) seed oil has the potential for use as an edible oil and as a pharmaceutical, cosmetic, insecticidal, and industrial product. In this study, we investigated, for the first time, the effect of cultivar and season on seed number, oil content, and fatty acid profiles as well as their proportions in different cucumber cultivars. We examined the effects of spring and autumn seasons on seed oil content and fatty acid composition in 46 cucumber cultivars and one wild species of cucumber (C. anguria) grown in greenhouse experiments in 2013 and 2014. Seed oil was determined using the Soxhlet method and fatty acids using the gas chromatography-mass spectrometry method. Seed oil content in the cucumber seeds ranged from 41.07% in ‘Hazerd’ to 29.24% in ‘Lubao’ while C. anguria had 23.3%. Fatty acids detected were linoleic (C18:2), palmitic (C16:0), oleic (C18:1), stearic (C18:0), linolenic (C18:3), behenic (C22:0), arachidic C20:0), lignoceric (C24:0), eicosenoic (C20:1), palmitoleic (C16:1), and myristic (C14:0), among other unidentified fatty acids. The results showed significant effects of cultivar genotype, growing season, and interactions on the variables examined. The content of seed oil and fatty acids differed significantly among the cultivar genotypes. Spring-grown cucumbers had higher quantities of oil than the autumn-grown cucumbers. The content of fatty acids (mainly palmitic, palmitoleic, stearic, oleic, eicosenoic, and lignoceric) also was higher in spring. In autumn there were more seeds, and higher linoleic, linolenic, and other unspecified fatty acids. The higher the oleic acid content the lower was the linoleic acid indicating a strong negative relationship in these two fatty acids. The higher the seed oil content the higher was linoleic and oleic indicating a positive relationship between the seed oil and the two fatty acids. Results of this study provide important information applicable in improving management and production of cucumber seed oil especially considering its versatility in uses. Furthermore, the wide range of fatty acids found in the studied cucumber cultivars could be used in the production of novel industrial oils through genetic engineering.

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High temperature stress is a major limiting factor for pepper productivity, which will continue to be a problem under climate change scenarios. Developing heat tolerant cultivars is critical for sustained pepper production, especially in tropical and subtropical regions. In fruiting crops, like pepper, reproductive tissues, especially pollen, are the most sensitive to high temperature stress. Typically, pollen viability and germination are assessed through staining and microscopy, which is tedious and potentially inaccurate. To increase efficiency in assessing pollen traits of pepper, the use of impedance flow cytometry (IFC) has been proposed. We conducted three independent experiments to determine the most effective methodology to use IFC for evaluating pollen traits for heat tolerance in pepper. Seven floral developmental stages were evaluated, and stages 3, 4, and 5 were found to best combine high pollen concentration and activity. Flowers in development stages 3, 4, or 5 were then heat treated at 41, 44, 47, 50, and 55 °C or not heat treated (control). The critical temperature to assess heat tolerance using IFC was found to be 50 °C, with a reduction in pollen activity and concentration occurring at temperatures greater than 47 °C. Twenty-one entries of pepper were then accessed for pollen traits using the staining and IFC methods over 2 months, April (cooler) and June (hotter). Growing environment was found to be the greatest contributor to variability for nearly all pollen traits assessed, with performance during June nearly always being lower. PBC 507 and PBC 831 were identified as being new sources of heat tolerance, based on using IFC for assessing pollen. Pollen viability determined by staining and pollen activity determined using IFC were significantly positively correlated, indicating that IFC is an efficient and accurate method to assess pollen traits in pepper. This work provides a basis for further research in this area and supports more efficient breeding of heat-tolerant cultivars.

Open Access