Location: Plant, Soil and Nutrition ResearchTitle: Carotenoid profiling of leaves of selected eggplant accessions subjected to drought stress Author
Submitted to: Food Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2016
Publication Date: 1/5/2017
Citation: Mibei, E., Ambuko, J., Giovannoni, J.J., Onyango, A., Owino, W. 2017. Carotenoid profiling of leaves of selected eggplant accessions subjected to drought stress. Food Science and Nutrition. 5(1):113-122. Interpretive Summary: African eggplants (Solanum aethiopicum and S. macrocarpon) are among the most economically important and valuable vegetable and fruit crops. They are a major source of biologically active nutritional substances and metabolites which are essential for plant growth, development, stress adaptation and defense. Among these metabolites are the carotenoids which act as accessory pigments for photosynthesis and precursor to plant hormones. Though African eggplants are known to be resistant to various abiotic stresses, the effect of these stresses on secondary metabolites has not been well defined. The objective of this study was to establish the effect of drought stress on carotenoid profiles of nineteen African eggplant accessions selected based on leaf and fruit morphological traits. The results indicate that environmental stress has a significant influence on crop nutritional quality. Resulting insights may facilitate improved breeding and selection with stress tolerance in mind.
Technical Abstract: This study focused on the quantification of carotenoids of the leaves of African eggplants commonly consumed as leafy and fruit vegetables. The results gave comparative profiles of carotenoids at different growth and developmental stages and under drought stress. Stress was achieved by limiting irrigation and maintaining the wilting state of the crops. Fresh leaves were sampled at different maturity stages; before stress, 2 weeks and 4 weeks after stress for carotenoid analysis. The fresh harvested leaf tissues were immediately frozen in liquid nitrogen and ground. Analysis was carried out using a HPLC. Major carotenoids viz;. Xanthophylls (neoxanthin, violaxanthin, zeaxanthin and lutein) and carotenes (ß–carotene and a–carotene), phytofluene, lycopene, phytoene as well as chlorophylls (chlorophyll-b and Chlorophyll-a) were measured. The carotenoids increased with maturity stage of the crop. Although the stressed crops reported significantly decreased amount of carotenes, chlorophylls, neoxanthin and violaxanthin, the concentration of zeaxanthin increased with stress whereas lutein had no significant change. Chlorophyll-a was significantly high in all the control accessions. Two accessions reported significantly higher contents of carotenoids as compared to the other accessions. The results of this study indicate that water stress has significant impact on the concentration of some carotenoids and photosynthetic pigments.