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1.
Carotenoids are not only important to the plants themselves but also are beneficial to human health. Since citrus fruit is a good source of carotenoids for the human diet, it is important to study carotenoid profiles and the accumulation mechanism in citrus fruit. Thus, in the present paper, we describe the diversity in the carotenoid profiles of fruit among citrus genotypes. In regard to carotenoids, such as β-cryptoxanthin, violaxanthin, lycopene, and β-citraurin, the relationship between the carotenoid profile and the expression of carotenoid-biosynthetic genes is discussed. Finally, recent results of quantitative trait locus (QTL) analyses of carotenoid contents and expression levels of carotenoid-biosynthetic genes in citrus fruit are shown.  相似文献   

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Mature green cherry tomato fruit were harvested and treated with ultraviolet-C (UV-C) irradiation at a predetermined dose of 4.2 kJ m−2, and stored at 18 °C for 35 days. The effects of UV-C treatment on color change, pigment contents, and the expression of major genes involved in carotenoid metabolism, including Psy 1, Pds, Lcy-β, and Lcy-ɛ, encoding phytoene synthase, phytoene desaturase, lycopene β-cyclase and lycopene ɛ-cyclase, respectively, were examined. The UV-C treated fruit developed a pink red color in contrast to the normal orange red color of control fruit. Lycopene accumulation during ripening in UV-C treated fruit was significantly inhibited but its final content was not affected. However, both accumulation and final content of β-carotene were significantly suppressed in UV-C treated fruit. The lower content of β-carotene, leading to a higher lycopene to β-carotene ratio, is probably responsible for the altered color phenotype in UV-C treated fruit. Psy 1, a major gene involved in lycopene synthesis was inhibited by UV-C irradiation. Significantly suppressed expression of Lcy-β gene was also observed in UV-C treated fruit. Thus it is possible that the lower transformation from lycopene to carotenes contributed to the relatively stable content of lycopene.  相似文献   

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Major progress has been made over the last few years in the identification and regulation of tomato ripening genes. At least 25 genes showing elevated expression during ripening have been cloned and several, including polygalacturonase, which modifies fruit textures, have been shown to be ripening-specific. In addition, genes have been cloned for ACC synthase and ACC oxidase, which control the synthesis of ethylene, which plays a critical role in ripening. Inhibition of expression of polygalacturonase, pectinesterase, ACC synthase, ACC oxidase and phytoene synthase has been achieved in transgenic plants, using antisense technology. The expression of several genes has also been inhibited by sense gene suppression. New traits caused by these transgenes are stably inherited. Antisense tomatoes with reduced polygalacturonase have improved textural qualities which are being exploited commercially for the fresh and processed markets. Overexpression of phytoene synthase has been shown to restore carotenoid production in the yellow flesh mutant and can be used to enhance colour in other cultivars. Antisense fruit in which ACC synthase or ACC oxidase are inhibited show slower ripening and reduced over-ripening. ACC oxidase antisense genes have also been shown to delay leaf senescence. It is to be expected that further genes determining other quality traits will be identified and manipulated soon.  相似文献   

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Heritabilities and Minimum Gene Number Estimates of Carrot Carotenoids   总被引:1,自引:0,他引:1  
Summary Broad sense heritabilities and gene numbers were estimated for the production of total carotenoids and the major component carotenoids of carrot storage roots: phytoene, ζ-carotene, β-carotene, α-carotene, and lycopene. Two crosses with different backgrounds were evaluated: orange B493 × white QAL and orange Brasilia × dark orange HCM. The HCM (high carotene mass selection), Brasilia and B493 parents had both α-carotene and β-carotene, but HCM had proportionally more α-carotene. Carotene content in F 2 populations ranged from 522 ppm to 1714 ppm in Brasilia × HCM and from 0 to 695 ppm in B493 × QAL progeny. F 2 plants segregating for absence of α-carotene were identified in B493 × QAL. Broad-sense heritabilities ranged from 28% to 48% for all carotenes except lycopene and phytoene where estimates were 44% to 89% in the Brasilia × HCM cross, All heritability values exceeded 88% for the B493 × QAL cross, except one estimate for lycopene. The estimated number of genes was 4 conditioning α-carotene, 2 to 3 each for β-carotene and total carotenes and one each for ζ-carotene, lycopene and phytoene in the orange × dark orange cross. In the orange × white cross, the estimates were 4 genes for α-carotene, 1 to 2 each for lycopene and total carotenes and 1 for each of the other carotenes. These results are in general agreement with QTL studies and they provided evidence for continuous inheritance of α-carotene, β-carotene and total carotenoids in the orange × dark orange cross and discrete inheritance for β-carotene and total carotenoids in the orange × white cross.Part of thesis “Biometrical studies and quantitative trait loci associated with major products of the carotenoids pathway of carrot (Daucus carota L.)” presented by the first author as partial fulfillment of the requirement of the PhD degree in Plant Breeding and Plant Genetics, UW-Madison, USA, 2001.  相似文献   

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Carnation (Dianthus caryophyllus L.) belongs to the family Caryophyllaceae in the order Caryophyllales. Plants in this order do not accumulate carotenoids in petals. To understand how carotenoid accumulation is controlled in carnation petals, we analysed the expression of genes related to carotenoid accumulation. Petals at an early stage of development accumulated small amounts of carotenoids. As petals matured, their carotenoid content decreased to extremely low levels. In contrast, carnation leaves contained substantial amounts of carotenoids that are essential for photosynthesis. Most of the carotenogenic genes were expressed in petals at levels similar to those in leaves, and the expression levels of these genes increased during petal development. Genes encoding phytoene synthase and lycopene ε‐cyclase were exceptions. Their expression levels in petals were very low compared with those in leaves. Expression of the gene encoding carotenoid cleavage dioxygenase 4 was detected in neither leaves nor petals. These data suggest that the low levels of carotenoids in carnation petals are caused not by enzymatic degradation but rather by low rates of carotenoid biosynthesis.  相似文献   

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Citrus fruit are non-climacteric. However, exposure to exogenous ethylene, e.g., during ethylene degreening, stimulates various ripening-related processes in the peel tissue, such as destruction of the green chlorophyll pigments and accumulation of orange/yellow carotenoids. Nonetheless, it is not yet known whether exogenous ethylene affects internal ripening processes in citrus flesh. To address this question, we examined the possible effects of ethylene on taste, aroma, perceived flavor, and nutritional quality of various citrus fruit, including ‘Navel’ oranges, ‘Star Ruby’ grapefruit and ‘Satsuma’ mandarins. Exposure to ethylene enhanced peel color break, and respiration and ethylene production rates in all citrus fruit tested. However, ethylene degreening had no effect on juice total soluble solids and acid contents, and had only minor effects on contents and composition of juice aroma volatiles. Moreover, sensory analysis tests revealed that ethylene degreening did not affect the flavor of oranges and grapefruit, but marginally impaired sensory acceptability of mandarins; the latter change could be attributed, at least partially, to storage of the fruit for 5 days at 20 °C. Nevertheless, ethylene degreening did not enhance off-flavor perception or accumulation of off-flavor volatiles, nor had any effect on levels of health promoting compounds such as vitamin C, total phenols and flavonoids, or antioxidant-activity of citrus juice. We conclude that although ethylene affects peel color break, it is probably not involved in regulation of internal ripening processes in citrus fruit and, therefore, does not impair internal fruit quality.  相似文献   

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Summary The common cultivated tomato (Lycopersicon esculentum Mill.) provides a major focus for improvement of crop quality through genetic engineering. Identification of ripening-related cDNAs has enabled the modification of specific aspects of ripening by manipulating gene expression in transgenic plants. By utilizing antisense RNA to modify expression of ripening genes, we have inhibited the production of the cell wall-metabolising enzymes polygalacturonase and pectinesterase and created transgenic plants that contain, effectively, single, targeted mutations affecting these genes. Furthermore, this approach has been used with previously unidentified cDNA clones to enable both functional identification and manipulation of genes involved in ethylene production (ACC oxidase) and carotenoid biosynthesis (phytoene synthase). The use of antisense RNA targeted to specific genes to alter ripening phenotypes and improve commercial utility of fruit by affecting shelf-life, processing characteristics and nutritional content is discussed.We have used the extreme ripening-impaired mutant, ripening inhibitor (rin) to identify additional genes implicated in the ripening process. This approach has resulted in the cloning of several novel ripening-related mRNAs which are now being studied by antisense experiments. This may enable identification and manipulation of additional genes involved in processes such as softening, flavour and aroma generation and susceptibility to pathogens.Abbreviations ACC 1-aminocyclopropane-1-carboxylic acid - PE pectinesterase - PG polygalacturonase - SAM S-adenosyl methionine - SARs scaffold attachment regions  相似文献   

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Apricots are climacteric fruits with a high susceptibility to flesh softening and loss of flavor during postharvest storage, and most of the ripening processes are regulated by ethylene, which also has an effect on its own biosynthesis. To understand this process in apricot, inhibition of ethylene biosynthesis and perception was performed for studying key genes involved in the ethylene biosynthetic pathway. Apricots, cv. “Patterson”, were harvested with yellow-green ground color and immediately treated with either the ethylene perception inhibitor 1-methyl cyclopropene (1-MCP) at 10 μL L−1 or the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) at 1 g L−1. After treatment, quality and physiological attributes such as firmness, color, total soluble solids, acidity, fruit weight, ethylene production and respiration rates were evaluated every 2 d until they ripened at 20 °C. Gene expression analysis was performed by quantitative polymerase chain reaction (qPCR). Both ethylene inhibitors were effective in reducing ethylene production, respiration rate and fruit softening. Three 1-aminocyclopropane-1-carboxylic-acid synthase (ACS) genes were characterized, but only the expression of ACS2 was highly reduced by ethylene inhibition, suggesting a key role in ethylene synthesis at ripening. Contrarily, ACS1 and ACS3 showed a higher expression under ethylene inhibition suggesting that the corresponding genes are individually regulated in a specific mode as observed in other climacteric fruits. Finally, changes in 1-aminocyclopropane-1-carboxylic-acid oxidase genes did not show a consistent pattern of ethylene modulation.  相似文献   

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本研究以‘皮球桃’及其芽变桃不同发育阶段的果肉与叶片中脉为试材,采用HPLC法测定两种桃中类胡萝卜素的组分构成与含量积累,并对类胡萝卜素生物合成及代谢过程中关键基因的转录水平进行实时荧光定量PCR分析。结果显示,芽变桃中类胡萝卜素总含量极显著高于‘皮球桃’,β-隐黄质、α-胡萝卜素和β-胡萝卜素的积累差异是造成两种桃呈色不同的主要原因。实时荧光定量PCR结果表明,CCD4在果肉和叶片中脉中的表达规律完全相同,且与类胡萝卜素的积累模式一致,因此CCD4的表达差异可能是导致芽变桃果肉及叶片中脉突变为黄色的重要原因。本研究利用‘皮球桃’及其自然突变体作为探讨类胡萝卜素合成及代谢调控的理想材料,以期从生理及分子层面揭示变异黄桃的形成机理,为桃的类胡萝卜素调控基因开发、变异的早期鉴定、认识和选育富含类胡萝卜素桃品种提供理论基础。  相似文献   

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Tomato (Lycopersicon esculentum L.) fruit are an important source of antioxidant (mainly pigment) compounds, as well as lycopene, β-carotene, ascorbic acid and polyphenols. Differentiation of the final product in the market requires an accurate evaluation of these value-adding compounds. Because of this, we have undertaken a comparison of the spectral characterisation of the tomato fruit surface pigments from the immature to over-ripe stage, using spectroscopy techniques based on visible fluorescence emission upon excitation in the same or ultraviolet spectral regions. The aim was to verify the spectral band for optimal conditions for fruit harvesting using non-destructive techniques. The pattern of pigment composition changed markedly during ripening and showed progressive disappearance of chlorophyll with a concomitant increase in carotenoids until the fully ripe stage. The main fluorescence spectral features belonging to anthocyanins, flavonoids, carotenoids and chlorophyll a after excitation of skin tomato pigments at different laser wavelengths was identified. In comparing, the fluorescence spectral ratios at the excitation wavelength λexc = 266 nm, significant differences were obtained for the spectral ratios of chlorophyll/flavonoids and carotenoids/chlorophyll. Positive correlation coefficients were found for the carotenoids/flavonoids (0.780) ratios and negative ones for the carotenoids/chlorophyll ratios (−0.513).Analysis of fluorescence resulted in determination of the most useful laser radiation for remote non-invasive measurements with laser-induced fluoresence (LIF): for the ripening stage, λexc = 266 nm was the optimal laser wavelength, since the induced fluorescence spectra obtained appeared to differ with the physiological stage of the fruit.  相似文献   

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Two citrus types (‘Fallglo’ and ‘Lee × Orlando’) exhibiting differential fruit degreening response when treated with ethylene were selected. Fruit were harvested at commercial maturity but at different developmental periods (Harvest I, II and III). Rate of color change was greater in ‘Fallglo’ than in ‘Lee × Orlando’ when fruit were treated with 5 μL L−1 of ethylene for 24 h. After 24 h of transfer of fruit to ethylene-free storage, rate of change decreased in ‘Fallgo’ and exhibited varied response in ‘Lee × Orlando’ depending on harvest date. ‘Fallglo’ fruit from Harvests I and II were completely degreened at the end of storage for 7 d; however ‘Lee × Orlando’ were not and were green in color. No difference in seedling triple response was observed between ‘Fallglo’ and ‘Lee × Orlando’ and sequences of the four ethylene receptors were identical between them. Expression of genes involved in ethylene biosynthesis and signaling pathways were studied in flavedo to test if differences in these pathways were correlated with differential ethylene sensitivity of the citrus types. Basal levels of ACS2 and ACO expressions declined as maturity progressed, and ethylene-induced expression of ACS1 and ACO were influenced by fruit maturity. At Harvests I and II, ethylene-induced increase in ACS1 and ACO expressions and ACC levels were greater in ‘Fallglo’ than in ‘Lee × Orlando’. Ethylene treatment influenced MACC content only during Harvest I in ‘Lee × Orlando’. MACC levels were generally higher in ‘Lee × Orlando’ than in ‘Fallglo’. Expressions of ETR1 and ETR2 were ethylene responsive in ‘Fallglo’ and only ETR1 expression was ethylene responsive in ‘Lee × Orlando’. Ethylene had more impact on ETR1 expression in ‘Fallglo’ than in ‘Lee × Orlando’. Ethylene had a negative effect on ETR3 expression which was more pronounced in ‘Lee × Orlando’ than in ‘Fallglo’. Expressions of ERS1, CTR1, EIN2, EIL1 and EIL2 were not affected by ethylene in both citrus types. Expression of chlorophyllase gene and rate of total chlorophyll degradation were higher in ‘Fallglo’ than in ‘Lee × Orlando’ during ethylene treatment. Differential degreening behavior of ‘Fallglo’ and ‘Lee × Orlando’ correlated with peel maturity, and factor(s) downstream of ethylene signaling but upstream of ethylene biosynthesis play a role in the differential sensitivity.  相似文献   

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两个杏品种不同成熟期果实品质变化研究   总被引:3,自引:0,他引:3  
以金太阳(Prunus armeniaca Golden-sun)和魁金杏(Prunus armeniaca Kuiijn)为试材,研究其在绿熟期、商熟期和完熟期果实中类黄酮、类胡萝卜素等品质指标的变化。结果表明:两个杏品种果实单果重、可溶性固形物、Vc含量、可溶性糖、类黄酮和类胡萝卜素含量均随着果实的成熟不断升高,在完熟期达到最高,魁金高于金太阳;果实硬度和有机酸含量均随着果实成熟度的增加而降低,在完熟期达到最低,魁金低于金太阳,魁金果实品质优于金太阳。  相似文献   

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柿果类胡萝卜素化学成份及其含量研究   总被引:1,自引:0,他引:1  
袁冰  徐华龙  冷平 《中国农学通报》2006,22(10):277-277
对柿果中类胡萝卜素化学成份及其含量的季节性变化以及栽培条件的影响等进行了调查,旨在为柿色素代谢及其功能性成分合成与调控等的深入研究奠定基础。结果如下:柿果实中的色素成份为玉米黄质、β-隐黄质、β-胡萝卜素、叶黄素和番茄红素;果皮中的类胡萝卜素总含量约是果肉中的6-11倍;按类胡萝卜素组成成分的含量由高至低,果皮依次为玉米黄质、β-隐黄质、β-胡萝卜素、叶黄素和番茄红素;而果肉依次为β-隐黄质、玉米黄质和β-胡萝卜素。结果表明,柿果肉主要色素成份为功能性β-隐黄质。温室栽培磨盘柿果中功能性成分β-隐黄质含量是露地的3倍。供试7品种间色素成分与含量有很大区别。  相似文献   

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