Identification of malodorous, a wild species allele affecting tomato aroma that was aelected against during domestication

Vegetable cultivation favored the inclusion of pleasant aromas in the produce, whereas unpleasant aromas were selected against. Introgression lines, generated by hybridization of a cultivated tomato (Lycopersicon esculentum) to its wild relative L. pennellii, were used to map quantitative trait loci (QTL) that influence tomato aroma. A marked undesirable flavor was detected by taste panelists in L. pennellii fruits and was related to an introgressed segment from the short arm of chromosome 8. Analysis of the ripe fruits' volatiles of chromosome 8 introgressed lines revealed an up to 60-fold increase in the levels of 2-phenylethanol and phenylacetaldehyde, as compared to the cultivated tomato. This effect was associated with a 10 cM segment originating from the wild species. Although 2-phenylethanol and phenylacetaldehyde have favorable contribution to tomato aroma when present at low levels, phenylacetaldehyde has a nauseating objectionable aroma when present in levels >0.005 ppm. The loss of the ability to produce high levels of phenylacetaldehyde contributed to the development of desirable aroma of the cultivated tomato. The findings provide a genetic explanation for one of the aroma changes that occurred during the domestication of the tomato.     

The flavonoids of tomatoes

Tomatoes ( Lycopersicon esculentum Mill.) have been recognized as an important source of dietary flavonoids because of a high consumption worldwide. The qualitative and quantitative flavonoid compositions of assorted tomato cultivars including individual quantitative contributions of the five most significant flavonoids have been determined in this work. The dihydrochalcone phloretin 3',5'-di-C-beta-glucopyranoside and the flavonol quercetin 3-O-(2'-O-beta-apiofuranosyl-6'-O-alpha-rhamnopyranosyl-beta-glucopyranoside) were identified for the first time in Solanaceae spp. and found to be among the main flavonoids in all cultivars. Phloretin 3',5'-di-C-glc is the first C-glycoside identified in tomatoes and also the first dihydrochalcone from this species. In addition, chalconaringenin, kaempferol 3-rutinoside, and quercetin 3-rutinoside (rutin), though previously reported to occur in tomato, were fully characterized by extensive use of 2D NMR techniques and high-resolution LCMS. The total flavonoid content of different tomato types varied from 4 to 26 mg 100 (-1) g FW with chalconaringenin as the predominant compound comprising 35 to 71% of the total flavonoid content. The individual quantities of quercetin 3-O-(2'- O-beta-apiofuranosyl-6'- O-alpha-rhamnopyranosyl-beta-glucopyranoside) and phloretin 3',5'-di-C-beta-glucopyranoside was similar to that of rutin in several cultivars.     

Physico – biochemical properties of tomato (Solanum lycopersicum) grown in heavy – metal contaminated soil

The present study was undertaken to investigate the effect of soil contamination with heavy metals on physico-biochemical properties of tomato fruit. The deleterious effect of soil contamination on the quality and quantity of tomato plant yield was determined. Harvested tomato fruit characteristics including fruit length, diameter, volume and fresh and dry weights, total soluble solids, titratable acidity, lycopene and carbohydrates contents were measured in tomato fruits cultivated in soil contaminated with industrial effluents. In addition, some secondary metabolites (total phenols and flavonoids), micro- and macronutrients were also detected. Residual heavy metals (Cd, Co, Ni and Pb) were examined in the harvested fruits. The obtained results were compared with those of tomato fruits cultivated in non-contaminated soil. Results demonstrate that soil contamination with heavy metals have a negative effect on tomato fruits characteristics, titratable acidity, total soluble solids, lycopene, ascorbic acid, micro-elements and carbohydrates content. Moreover, fruits originated from plants grown in contaminated soil possess high phenols and flavonoids contents and higher heavy metals content compared to control fruits. It is recommended that fruits cultivated in that area not to be eaten by large quantities, to avoid excessive accumulation of heavy metals in the human body.

Abbreviations: (AsA): Ascorbic acid; (DTPA): diethylenetriamine penta acetic acid; (TA): Titratable acidity; (TSS): Total soluble solids     

Identification and quantification of stilbenes in fruits of transgenic tomato plants (Lycopersicon esculentum Mill.) by reversed phase HPLC with photodiode array and mass spectrometry detection

Reversed-phase high-performance liquid chromatography (RP-HPLC) with photodiode array (PDA) and mass spectrometry (MS) detection was employed to study the accumulation of stilbenes and other naturally occurring polyphenol intermediates of flavonoid pathway in tomato fruits of plants genetically modified to synthesize resveratrol. The transgenic tomato fruits were obtained by overexpression of a grapevine gene encoding the enzyme stilbene synthase in tomato plants (Lycopersicon esculentum Mill.). Stilbenes and flavonoids, either glycosylated or free, were simultaneosly identified by electrospray interface (ESI)-MS in negative ionization mode and were quantified by PDA detection at the wavelength corresponding to their maximum absorbance. The two detectors were coupled online with an HPLC system utilizing a narrow-bore C18 reversed-phase column, which was eluted by a multistep gradient of increasing concentration of acetonitrile in water containing 0.5% (v/v) formic acid. The results of these analysis revealed that the genetic modification of the tomato plants originated different levels of accumulation of four stilbenes (i.e., trans- and cis-piceid and trans- and cis-resveratrol) in their fruit depending on the stages of ripening. Either at immature or at mature stages of ripening the stilbenes were preferentially accumulated in the fruit peel as the glycosylated form. The highest amount of trans-piceid and trans-resveratrol were found in the peel of fruits harvested at mature stage of ripening. The variations in the levels of rutin, naringenin, and chlorogenic acid found in the samples extracted from the fruits of transgenic tomato plants, in comparison to that determined in the control lines, seemed to be related to the genetic transformation, whose effect on the flavonoid biosynthetic pathway needs to be elucidated by additional studies.     

Identification of an allele attributable to formation of cucumber-like flavor in wild tomato species (Solanum pennellii) that was inactivated during domestication

Carbon 6 (C6)-aldehydes formed by fatty acid 13-hydroperoxide lyase (13HPL) specific to fatty acid 13-hydroperoxides (13-HPO) are important flavor constituents in fresh tomato fruits. C9-aldehydes are usually formed by 9/13HPL showing dual specificity to 9- and 13-HPOs and are scarcely found in tomato fruits. Mature red fruits of one of the introgression lines, IL1-4, generated by hybridization of a cultivated tomato (Solanum lycopersicon) to its wild relative Solanum pennellii, form high amounts of C9-aldehydes upon homogenization. The IL1-4 fruits showed high 9/13HPL activity. One of the genes isolated from IL1-4 showed a high similarity to plant 9/13HPLs. Recombinant proteins expressed in Escherichia coli showed 9/13HPL activity. Cleaved amplified polymorphic sequence analyses indicated that the gene was specific to IL1-4 and S. pennellii. S. lycopersicon had a gene having high similarity to the S. pennellii gene. It was absent in IL1-4. Among the differences of amino acid residues found between the two genes, a Cys to Ser exchange may be responsible for the inactivation of resultant protein product of S. lycopersicon gene because the Cys is an essential amino acid residue for HPL activity. From these observations, it could be assumed that a tomato gene corresponding to S. pennellii 9/13HPL gene had been inactivated through domestication of tomatoes.     

Definition of nonvolatile markers for flavor of tomato (Lycopersicon esculentum mill.) as tools in selection and breeding

A methodology for flavor and composition assessment of processed tomato juice samples was developed using a wide range of commercial processing tomato varieties (Lycopersicon esculentum) grown in Spain and the United States. Fruitiness intensity was found by a trained panel to best describe overall tomato flavor. For two consecutive years, fruitiness intensity was significantly dependent on growing location and variety, and it was consistently linked to increased levels of glucose and reducing sugars and decreased glutamic acid content. Using the same procedure on a population of 176 breeding lines derived from the wild species of Lycopersicon pimpinellifolium, it was shown that tomato fruitiness intensity was significantly correlated to reducing sugars/glutamic acid ratio and glucose and glutamic acid contents. The definition of markers for tomato flavor of processed juice can provide the tomato breeder and processor with reliable analytical tools that can be applied in a straightforward way for the identification of raw materials that can be processed into juice with predictably high or low fruitiness.     

A chemosystematic study of the flavonoids of Vigna

Summary Flavonoid chemical markers together with other biochemical markers and/or morphological data can provide useful characters for defining species in Vigna genus. In this paper flavonid HPLC fingerprints have been utilized to assess taxonomic relationships amongst species and accessions of Vigna. Within the taxa analysed there is evidence of both infra- and interspecific chemical variations. In some species chromatographic data support evidence for the existence of different flavonoid chemotypes, which may reflect differences in geographic origin. As far as interspecific relationships are concerned, species belonging to sections Vigna, Plectotropis and Ceratotropis do not show flavonoid glycosides in common with cultivated lines of Vigna. By contrast, some relationships have been found between cultivated lines and wild species of section Catiang. Kaempferol-3-rutinoside and an unidentified kaempferol-glycoside were the only flavonoids detected in the three subgenera analysed. Finally, a greater variability in flavonoid aglycone class and glycosylation pattern has been observed in cultivars of V. unguiculata (L.) Walp. compared to the wild species. This observation may confirm that cultivation and/or domestication may cause or increase species diversification.     

Role of endogenous flavonoids in resistance mechanism of Vigna to aphids

Cultivated and wild species of the genus Vigna were screened for their flavonoid content. Flavonoid HPLC analyses clearly showed that cultivated lines of cowpea (Vigna unguiculata L. Walp.) are very similar from a qualitative point of view, always showing three flavonoid aglycons: quercetin, kaempferol, and isorhamnetin. In addition, a positive relationship between resistance/susceptibility characteristics against aphids and flavonoid glycoside content of cowpea lines was found. The resistant lines showed a flavonoid content higher than that of susceptible ones. In vitro bioassays proved that, among endogenous flavonoids, quercetin and isorhamnetin possess a good inhibitory aphid reproduction rate. Flavonoid HPLC analyses of wild Vigna species supported evidence for the existence of different flavonoid chemotypes in some species of section Vigna. There are kaempferol chemotypes, kaempferol being the main aglycon detected, quercetin chemotypes, containing quercetin glycosides only, and two isorhamnetin chemotypes. When the resistance characteristics to aphids in different chemotypes of the same species were tested, it became evident that quercetin or isorhamnetin chemotypes showed a higher level of resistance compared to kaempferol chemotypes in the same species, thus demonstrating a direct involvement of quercetin or isorhamnetin in the resistance mechanism. These results can provide useful information for further studies on gene expression of resistance factors.     

Particle-stabilizing effects of flavonoids at the oil-water interface

It has been shown that some common food flavonoids can act as excellent stabilizers of oil-in-water emulsions through their adsorption as water-insoluble particles to the surface of the oil droplets, i.e., Pickering emulsions are formed. Flavonoids covering a wide range of octanol-water partition coefficients (P) were screened for emulsification behavior by low shear mixing of flavonoid+n-tetradecane in a vortex mixer. Most flavonoids with very high or very low P values were not good emulsifiers, although there were exceptions, such as tiliroside, which is very insoluble in water. When a high shear jet homogenizer was used with 20 vol% oil in the presence of 1 mM tiliroside, rutin, or naringin, much finer emulsions were produced: the average droplet sizes (d32) were 16, 6, and 5 μm, respectively. These results may be highly significant with respect to the delivery of such insoluble compounds to the gut, as well as their digestion and absorption.     

Disposition of selected flavonoids in fruit tissues of various tomato (lycopersicon esculentum mill.) Genotypes

Flavonoids have been studied extensively because they offer great potential health benefits. In this study, enzymatic hydrolysis of glycosylated quercetin, kaempferol, and naringin was used to obtain their sugar-free aglycones. The investigation also employed a validated HPLC method to obtain the chiral disposition of the aglycone naringenin enantiomers. These analyses were conducted on exocarp, mesocarp, and seed cavity tissues of field-grown tomato (Lycopersicon esculentum Mill.) mutants (anthocyanin absent, atroviolacea, and high pigment-1) and their nearly isogenic parent (cv. Ailsa Craig) at immature green, "breaker", and red ripe maturity stages. Concentrations of all flavonoids using enzymatic hydrolysis were significantly higher than previously reported concentrations using acid hydrolysis. Presumably, this occurred due to a more specific and rapid hydrolysis of the glycoside moiety by the beta-glucosidase enzyme. The glycoside S-naringin was the predominant enantiomer in all fruit tissues, although the aglycones free R- and S-naringenin were detected in both exocarp and mesocarp. Whereas there was significantly more quercetin than kaempferol in exocarp tissue, they were present in about equal concentrations in the mesocarp. Quercetin concentrations were higher in the exocarp and mesocarp of immature green and breaker fruit of the high pigment-1 mutant than in the other genotypes, supporting the observed photoprotection and potential health benefits of the high pigment-1 tomato genotype.     

Sodium borohydride/chloranil-based assay for quantifying total flavonoids

A novel sodium borohydride/chloranil-based (SBC) assay for quantifying total flavonoids, including flavones, flavonols, flavonones, flavononols, isoflavonoids, flavanols, and anthocyanins, has been developed. Flavonoids with a 4-carbonyl group were reduced to flavanols using sodium borohydride catalyzed with aluminum chloride. Then the flavan-4-ols were oxidized to anthocyanins by chloranil in an acetic acid solution. The anthocyanins were reacted with vanillin in concentrated hydrochloric acid and then quantified spectrophotometrically at 490 nm. A representative of each common flavonoid class including flavones (baicalein), flavonols (quercetin), flavonones (hesperetin), flavononols (silibinin), isoflavonoids (biochanin A), and flavanols (catechin) showed excellent linear dose-responses in the general range of 0.1-10.0 mM. For most flavonoids, the detection limit was about 0.1 mM in this assay. The recoveries of quercetin from spiked samples of apples and red peppers were 96.5 +/- 1.4% (CV = 1.4%, n = 4) and 99.0 +/- 4.2% (CV = 4.2%, n = 4), respectively. The recovery of catechin from spiked samples of cranberry extracts was 97.9 +/- 2.0% (CV = 2.0%, n = 4). The total flavonoids of selected common fruits and vegetables were measured using this assay. Among the samples tested, blueberry had the highest total flavonoid content (689.5 +/- 10.7 mg of catechin equiv per 100 g of sample), followed by cranberry, apple, broccoli, and red pepper. This novel SBC total flavonoid assay can be widely used to measure the total flavonoid content of fruits, vegetables, whole grains, herbal products, dietary supplements, and nutraceutical products.     

乙烯受体基因LeETR1和LeETR4的克隆及在番茄果实中的表达

摘要：为研究野生型番茄（Lycopersicon esculentum Mill. cv . Lichun）和转反义ACS 番茄果实中乙烯受体基因LeETR1和LeETR4的表达与乙烯的关系，实验用RT-PCR方法扩增了乙烯受体基因LeETR1和LeETR4片段，用两片段作探针进行Northern 杂交。结果表明：两受体基因的表达在番茄果实成熟进程中变化不明显，LeETR4在同一时期的果实外果皮中表达水平低于其在辐射壁和中柱的表达。转反义ACS番茄果实中LeETR1和LeETR4的表达水平显著低于野生型番茄果实，外源乙烯处理转反义ACS番茄果实，促进两个受体基因的表达。可见果实中LeETR1和LeETR4的表达受乙烯调控的影响。     

Iodine biofortification in tomato

Iodine is an essential element in the human diet, and iodine deficiency is a significant health problem. No attempts to increase iodine content in plant‐derived food (biofortification) have so far been particularly effective. We studied iodine uptake in tomato (Solanum lycopersicum L.) to evaluate whether it is possible to increase the iodine concentration in its fruits. Iodine translocation and storage inside tomato tissues were studied using radioactive iodine. Potassium iodide was also supplied at different concentrations to tomato plants to evaluate the resulting iodide concentration both in the vegetative tissues and the fruits. The results indicate that iodine was taken up better when supplied to the roots using hydroponically grown plants. However, a considerable amount of iodine was also stored after leaf treatment, suggesting that iodine transport through phloem also occurred. We found that tomato plants can tolerate high levels of iodine, stored both in the vegetative tissues and fruits at concentrations that are more than sufficient for the human diet. We conclude that tomato is an excellent crop for iodine‐biofortification programs.     

The consumption of wild and semi-domesticated edible plants in the Arribes del Duero (Salamanca-Zamora,Spain): an analysis of traditional knowledge

The collection and consumption of wild (including naturalized) and semi-domesticated (cultivated and reverted to wild status, and neglected cultivated plants for food) edible plants in the rural communities of the Arribes del Duero (western Spain), a highly heterogeneous Mediterranean agroecosystem, were analysed. Through semi-structured interviews with 80 informants, data on the gathering, preparation and consumption of 76 wild edible plant species were acquired. To analyze how traditional knowledge varies with the characteristics of the informants, we performed an ANCOVA. The “age” variable was found to have a significant effect. The most frequently cited species in the study area (i.e. Rubus ulmifolius, Foeniculum vulgare, Quercus ilex, Laurus nobilis, Origanum vulgare) are widely consumed in the Mediterranean region. Also, from a cluster analysis it was observed that the grouping succession this territory matches those of analysed areas of the Iberian southwest. Certain species have traditionally been consumed as an important supplement to the diet, particularly during food shortages (i.e. Rumex induratus, Chondrilla juncea). Several species are ethnobotanical novelties, among which are Erodium botrys and Astragalus pelecinus, whose immature fruits are eaten raw as a snack. Some ecological and cultural aspects of the gathering of wild plants for food are discussed.     

Ten-year comparison of the influence of organic and conventional crop management practices on the content of flavonoids in tomatoes

Understanding how environment, crop management, and other factors, particularly soil fertility, influence the composition and quality of food crops is necessary for the production of high-quality nutritious foods. The flavonoid aglycones quercetin and kaempferol were measured in dried tomato samples (Lycopersicon esculentum L. cv. Halley 3155) that had been archived over the period from 1994 to 2004 from the Long-Term Research on Agricultural Systems project (LTRAS) at the University of California-Davis, which began in 1993. Conventional and organic processing tomato production systems are part of the set of systems compared at LTRAS. Comparisons of analyses of archived samples from conventional and organic production systems demonstrated statistically higher levels (P < 0.05) of quercetin and kaempferol aglycones in organic tomatoes. Ten-year mean levels of quercetin and kaempferol in organic tomatoes [115.5 and 63.3 mg g(-1) of dry matter (DM)] were 79 and 97% higher than those in conventional tomatoes (64.6 and 32.06 mg g(-1) of DM), respectively. The levels of flavonoids increased over time in samples from organic treatments, whereas the levels of flavonoids did not vary significantly in conventional treatments. This increase corresponds not only with increasing amounts of soil organic matter accumulating in organic plots but also with reduced manure application rates once soils in the organic systems had reached equilibrium levels of organic matter. Well-quantified changes in tomato nutrients over years in organic farming systems have not been reported previously.     

番茄ACO基因的克隆及其RNAi对乙烯释放的抑制

筛选番茄(Lycopersicon esculentum)幼苗cDNA文库获得与番茄抗性相关的克隆E11,设计引物,利用RT-PCR方法从受到病原侵染的番茄叶片中获得长1018bp的候选片段,同源性分析发现该片段与其它作物上发表的ACO基因序列高度同源,同源率83%～99%,推断该基因为番茄ACO基因家族的新成员。在此基础上,用BP克隆的方法构建该基因的RNA干涉(RNAi)载体pD311,对番茄进行遗传转化,获得卡那霉素抗性植株27棵,分子检测证实外源片段成功导入番茄基因组中。对获得的转基因植株的乙烯生成量测定结果表明,RNAi结构的导入大大抑制了内源ACO基因的表达,从而导致乙烯的生成大大降低。     

Study of flavonoids of Sechium edule (Jacq) Swartz (Cucurbitaceae) different edible organs by liquid chromatography photodiode array mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS)-based method was developed for the characterization of flavonoids from Sechium edule (Jacq) Swartz (Cucurbitaceae) edible organs, a plant cultivated since pre-Colombian times in Mexico where the fruit is called chayote. Chayote is used for human consumption in many countries; in addition to the fruits, stems, leaves and the tuberous part of the roots are also eaten. Eight flavonoids, including three C-glycosyl and five O-glycosyl flavones, were detected, characterized by nuclear magnetic resonance spectroscopic data, and quantified in roots, leaves, stems, and fruits of the plant by LC-photodiode array-MS. The aglycone moieties are represented by apigenin and luteolin, while the sugar units are glucose, apiose, and rhamnose. The results indicated that the highest total amount of flavonoids was in the leaves (35.0 mg/10 g of dried part), followed by roots (30.5 mg/10 g), and finally by stems (19.3 mg/10 g).     

供锌水平对番茄果实抗氧化性及风味品质的影响

为研究不同供锌水平对番茄产量及果实风味品质的影响,设置了不同的硫酸锌浓度的溶液培养试验。结果表明,无论缺锌还是多锌处理,番茄叶片叶绿素含量均显著下降;MDA含量显著上升,POD酶活性下降,以缺锌处理较为明显;缺锌处理SOD酶活性显著低于对照,而多锌处理稍高于对照,产量均下降。缺锌和多锌处理番茄果实的酸度增加,Vc含量降低;缺锌处理可溶性固形物显著下降,而多锌处理与正常处理没有差别。此外,缺锌和多锌处理果实中的番茄红素、总酚和总黄酮含量均低于正常处理,而抗氧化力没有差别,果实的芳香物质种类组成也发生了变化。说明适宜的锌水平是保证番茄高产、优质的重要因素。     

Re-examination of chromogenic quantitative assays for determining flavonoid content

Flavonoids in plants have gained worldwide attention because of their benefits for human health. This study compared three analytical procedures commonly used for determining flavonoid content in plant samples in terms of chromogenic relationships and the reaction products of different flavonoid structures by means of using flavonoid standards with flavone, flavonol, flavanone, flavanol, and isoflavone and analytes such as phenolic acids commonly found in plant extracts. Procedure A produced a stable color reaction between 3-hydroxy-4-keto-flavonoids (flavonols) and 5-hydroxyflavones and was highly sensitive. Procedure B produced color reactions among most of the flavonoids, but the reaction products had different colors and faded over time. Procedure B also produced a color reaction with caffeic and chlorogenic acid. Procedure C was the most sensitive. It produced a color reaction and, like procedure A, could be used to quantify flavonols and 5-hydroxyflavones, but also showed color reaction toward caffeic and chlorogenic acid. On the basis of the results, the current three procedures are not satisfactory for determining all of the types of flavonoid. Two issues needed to be clarified before a promising determination of flavonoid content could be performed with chromogenic assays. The first is a survey of the literature to screen the possible predominant component of flavonoid in analytes. The other is guided by the predominant flavonoid; a promising calibration curve for flavonoid detection can be established on the basis of the selection of an appropriate method and a chemical standard with an equivalent dose response to the predominant flavonoid.