Assessment of carotenoid degradation of grits from orange corn packaged in high barrier thermosealed pouches

Genetically improved maize varieties with high carotenoid levels and dark orange color have been developed to increase dietary consumption of macular carotenoids. However, postharvest and food processing conditions can cause isomerization and oxidation of carotenoids, reducing their potential impact on consumers' health. The purpose of this study was to assess the effectiveness of high barrier pouches in reducing carotenoid losses during the storage of dry-milled corn products. Orange corn grits were packaged in paper pouch bags, and three types of low-oxygen and low-moisture permeable (LOMP) pouches. Grits were packaged in each type of LOMP pouch with (LOMP-oxy) and without (LOMP-noxy) an oxygen scavenger. For six months, all pouches were stored at semi-controlled environmental conditions (22.5 ± 1.3°C, 32 ± 18% RH). After the storage period, orange corn grits stored in paper pouch bags lost 55% of total xanthophylls, whereas grits packaged in LOMP pouches only lost 8% of total xanthophylls. Orange Corn grits packaged in LOMP-oxy pouches had slightly higher carotenoid content than in LOMP-noxy pouches. Relative humidity fluctuation in the storeroom could have caused fluctuation in moisture content in the orange corn grits packaged in paper pouches, which may affect the rate of carotenoid degradation in the orange corn grits. Therefore, an effective control of the moisture content of the packaged dry-milled product and effective control of the temperature of pouches during storage conditions is essential to maximize carotenoid retention during the storage of dry-milled high carotenoid orange corn grits.

A Comparative Metabolomic Analysis Reveals Difference Manufacture Suitability in “Yinghong 9” and “Huangyu” Teas (Camellia sinensis)

“Yinghong 9” is a widely cultivated large-leaf variety in South China, and the black tea made from it has a high aroma and strong sweet flavor. “Huangyu” is a light-sensitive tea variety with yellow leaves. It was cultivated from the bud-mutation of “Yinghong 9” and has a very low level of chlorophyll during young shoot development. Due to chlorophyll being involved in carbon fixation and assimilation, the changes in photosynthesis might potentially affect the accumulation of flavor metabolites, as well as the quality of “Huangyu” tea. Although “Huangyu” has a golden yellow color and high amino acid content, the mechanism underlying the formation of leaf color and drinking value remains unclear. The widely targeted metabolomics and GC-MS analysis were performed to reveal the differences of key metabolites in fresh and fermented leaves between “Yinghong 9” and “Huangyu.” The results showed that tea polyphenols, total chlorophyll, and carotenoids were more abundant in “Yinghong 9.” Targeted metabolomics analysis indicated that kaempferol-3-glycoside was more abundant in “Yinghong 9,” while “Huangyu” had a higher ratio of kaempferol-3-glucoside to kaempferol-3-galactoside. Compared with “Yinghong 9” fresh leaves, the contents of zeaxanthin and zeaxanthin palmitate were significantly higher in “Huangyu.” The contents of α-farnesene, β-cyclocitral, nerolidol, and trans-geranylacetone, which were from carotenoid degradation and involved in flowery-fruity-like flavor in “Huangyu” fermented leaves, were higher than those of “Yinghong 9.” Our results indicated that “Huangyu” was suitable for manufacturing non-fermented tea because of its yellow leaf and flowery-fruity-like compounds from carotenoid degradation.

Raman Spectroscopy as a Robust New Tool for Rapid and Accurate Evaluation of Drought Tolerance Levels in Both Genetically Diverse and Near-Isogenic Maize Lines

Improving drought tolerance of crops has become crucial due to the current scenario of rapid climate change. In particular, development of new maize germplasm with increased drought tolerance is viewed as a major breeding goal to ensure sustainable food and feed production. Therefore, accurate rapid phenotyping techniques for selection of superior maize genotypes are required. The objectives of this study were to determine whether Raman microscopy technique can be applied for accurate assessment of drought-tolerance levels in both genetically diverse and near-isogenic maize lines that differ in their levels of drought-tolerance. Carotenoid degradation is known to be a direct stress response initiated by reactive oxygen species during osmotic stress such as drought. Using Raman mapping, we observed real-time changes in the rate of carotenoid degradation in chloroplasts that was dependent on the strength of osmotic stress. In addition, we showed that the rate of carotenoid degradation as measured by Raman spectroscopy correlates directly with drought tolerance levels of diverse maize genotypes. We conclude that Raman technique is a robust, biochemically selective and non-invasive phenotyping technique that accurately distinguishes drought tolerance levels in both genetically diverse and near-isogenic maize genotypes. We conclude that this technique can be further developed to render it suitable for field-based early assessment of breeding materials with superior drought-tolerance traits.

Microencapsulation by lyophilization of natural carotenoids using different wall materials/ Microencapsulação por liofilização de carotenoides naturais utilizando diferentes materiais de parede

Due to the biological importance of carotenoids, several works have been developed aiming for the reduction of carotenoid degradation, and one notable proposed alternative has been the formation of microcapsules. Therefore, the aim of the current paper was the microencapsulation of carotenogenic extracts from Rhodotorula mucilaginosa and Sporidiobolus pararoseus by a lyophilization method utilizing gum arabic, xanthan gum, sodium alginate and soy protein-like wall materials. The gum arabic showed the greatest efficiency of encapsulation for the R. mucilaginosa (66.3±0.8 %) and S. pararoseus (91.4±0.9 %) carotenogenic extracts, while the soy protein showed the lowest efficiency of encapsulation (40.7±1.1 % for R. mucilaginosa and 68.5±1.5 % for S. pararoseus). Scanning electron micrographs (SEM) showed irregular structure formation that was independent of the material utilized for the encapsulation. In this way, it was possible to observe that the wall materials directly affect the encapsulation efficiencies, morphology, and thermal behavior of the capsules of natural carotenoids.

Carotenoid metabolite and transcriptome dynamics underlying flower color in marigold (Tagetes erecta L.)

Marigold (Tagetes erecta L.) is an important ornamental plant with a wide variety of flower colors. Despite its economic value, few biochemical and molecular studies have explored the generation of flower color in this species. To study the mechanism underlying marigold petal color, we performed a metabolite analysis and de novo cDNA sequencing on the inbred line ‘V-01’ and its petal color mutant ‘V-01M’ at four flower developmental stages. A total of 49,217 unigenes were identified from 24 cDNA libraries. Based on our metabolites and transcriptomic analyses, we present an overview of carotenoid biosynthesis, degradation, and accumulation in marigold flowers. The carotenoid content of the yellow mutant ‘V-01M’ was higher than that of the orange inbred line ‘V-01’, and the abundances of the yellow compounds lutein, neoxanthin, violaxanthin, zeaxanthin, and antheraxanthin were significantly higher in the mutant. During flower development, the carotenoid biosynthesis genes were upregulated in both ‘V-01’ and ‘V-01M’, with no significant differences between the two lines. By contrast, the carotenoid degradation genes were dramatically downregulated in the yellow mutant ‘V-01M’. We therefore speculate that the carotenoid degradation genes are the key factors regulating the carotenoid content of marigold flowers. Our research provides a large amount of transcriptomic data and insights into the marigold color metabolome.

Esterified carotenoids are synthesized in petals of carnation (Dianthus caryophyllus) and accumulate in differentiated chromoplasts

Although yellow and orange petal colors are derived from carotenoids in many plant species, this has not yet been demonstrated for the order Caryophyllales, which includes carnations. Here, we identified a carnation cultivar with pale yellow flowers that accumulated carotenoids in petals. Additionally, some xanthophyll compounds were esterified, as is the case for yellow flowers in other plant species. Ultrastructural analysis showed that chromoplasts with numerous plastoglobules, in which flower-specific carotenoids accumulate, were present in the pale yellow petals. RNA-seq and RT-qPCR analyses indicated that the expression levels of genes for carotenoid biosynthesis and esterification in pale yellow and pink petals (that accumulate small amounts of carotenoids) were similar or lower than in green petals (that accumulate substantial amounts of carotenoids) and white petals (that accumulate extremely low levels of carotenoids). Pale yellow and pink petals had a considerably lower level of expression of genes for carotenoid degradation than white petals, suggesting that reduced degradation activity caused accumulation of carotenoids. Our results indicate that some carnation cultivars can synthesize and accumulate esterified carotenoids. By manipulating the rate of biosynthesis and esterification of carotenoids in these cultivars, it should be feasible to produce novel carnation cultivars with vivid yellow flowers.

A genetic mechanism for sexual dichromatism in birds

Sexual dichromatism, a difference in coloration between males and females, may be due to sexual selection for ornamentation and mate choice. Here, we show that carotenoid-based dichromatism in mosaic canaries, a hybrid phenotype that arises in offspring of the sexually dichromatic red siskin and monochromatic canaries, is controlled by the gene that encodes the carotenoid-cleaving enzyme β-carotene oxygenase 2 (BCO2). Dichromatism in mosaic canaries is explained by differential carotenoid degradation in the integument, rather than sex-specific variation in physiological functions such as pigment uptake or transport. Transcriptome analyses suggest that carotenoid degradation in the integument might be a common mechanism contributing to sexual dichromatism across finches. These results suggest that differences in ornamental coloration between sexes can evolve through simple molecular mechanisms controlled by genes of major effect.

Evaluation of Physiological and Biochemical Parameters of Some Wheat (Triticum aestivum) Genotypes under Salinity Stress

Physiological and biochemical parameters of plants among five wheat genotypes: KH-65, KRL-210, KRL-99, PBW-343 and PBW-373 were studied. Wheat plantlets, at three-leaf stage, were supplemented with 0, 50, 100, 150, 200, 250 and 300 mM of NaCl for 48 hours. Principal component analysis revealed chlorophyll and carotenoid degradation as best salinity indicator for studied wheat genotypes. Salt tolerance levels of studied wheat genotypes were in the order: KH-65 greater than KRL-210 greater than KRL-99 greater than PBW-343 greater than PBW-373. The study has revealed that observed physiological and biochemical data may provide an insight into the existence of internal mechanism in salt tolerant genotypes to cope up with salinity stress.

Effects of Exogenous Abscisic Acid (ABA) on Carotenoids and Petal Color in Osmanthus fragrans ‘Yanhonggui’

Osmanthus fragrans is a well-known native plant in China, and carotenoids are the main group of pigments in the petals. Abscisic acid (ABA) is one of the products of the metabolic pathway of carotenoids. Application of ABA could affect pigmentation of flower petals by changing the carotenoid content. However, little is known about the effects of ABA treatment on carotenoid accumulation in O. fragrans. In this study, different concentrations of ABA (0, 150 and 200 mg/L) were spread on the petals of O. fragrans ‘Yanhonggui’. The petal color of ‘Yanhonggui’ receiving every ABA treatment was deeper than that of the control. The content of total carotenoids in the petals significantly increased with 200 mg/L ABA treatment. In the petals, α-carotene and β-carotene were the predominant carotenoids. The expression of several genes involved in the metabolism of carotenoids increased with 200 mg/L ABA treatment, including PSY1, PDS1, Z-ISO1, ZDS1, CRTISO, NCED3 and CCD4. However, the transcription levels of the latter two carotenoid degradation-related genes were much lower than of the five former carotenoid biosynthesis-related genes; the finding would explain the significant increase in total carotenoids in ‘Yanhonggui’ petals receiving the 200 mg/L ABA treatment.