Simultaneous transgenic suppression of LePG and LeExp1 influences rheological properties of juice and concentrates from a processing tomato variety

Processing tomato lines suppressed in the accumulation of ripening-related polygalacturonase or expansin were generated by introduction of transgenes to silence expression of the LePG and LeExp1 genes, respectively. The rheological properties of juice and juice reconstituted from paste produced from lines suppressed in one of these genes, or in both, were compared with azygous controls. When assayed by measuring Bostwick consistency, paste produced from either suppressed LePG or suppressed LeExp1 lines and diluted to 5 degrees Brix was approximately 18% more viscous than that produced from controls. Simultaneous suppression of LePG and LeExp1 produced a small additional increase in viscosity of 4%. Rheometric flow analysis at 5 or 10 degrees Brix also showed substantial increases in the consistency index due to suppression of either LePG or LeExp1 alone, and a small additional increase when both genes were suppressed in the same transgenic line. Measurements by laser diffraction and [1H]NMR showed that suppression of LePG or LeExp1 accumulation altered the size distribution of insoluble particles and modified their surface properties. The data are consistent with suppression of LePG increasing serum viscosity, and suppression of either LePG or LeExp1 altering the properties of the insoluble particles and improving some aspect of particle-particle or particle-serum interaction, or both. However, relative to that caused by suppression of either gene alone, the additional increase in viscosity caused by simultaneous suppression of LePG and LeExp1 together was slight.     

Simultaneous transgenic suppression of LePG and LeExp1 influences fruit texture and juice viscosity in a fresh market tomato variety

Tomatoes are grown for fresh consumption or for processing of the fruit. Some ripening-associated processes of the fruit can either contribute to or degrade attributes associated with both fresh and processing quality. For example, cell wall disassembly is associated with loss of fresh fruit firmness as well as with loss of processed tomato product viscosity. Several enzymes contribute to cell wall polysaccharide disassembly. Polygalacturonase (PG, poly[1,4-alpha-d-galactouronide] glucanohydrolase, EC 3.2.1.15) is among the most abundant polysaccharide hydrolases in ripening tomato fruit and is the major contributor to pectin depolymerization. Expansin (LeExp1) is also abundant in ripening fruit and is proposed to contribute to cell wall disassembly by nonhydrolytic activity, possibly by increasing substrate accessibility to other enzymes. Suppression of either LePG or LeExp1 expression alone results in altered softening and/or shelf life characteristics. To test whether simultaneous suppression of both LePG and LeExp1 expression influences fruit texture in additive or synergistic ways, transgenic Lycopersicon esculentum var. Ailsa Craig lines with reduced expression of either LePG or LeExp1 were crossed. Fruits from the third generation of progeny, homozygous for both transgenic constructs, were analyzed for firmness and other quality traits during ripening on or off the vine. In field-grown transgenic tomato fruit, suppression of LeExp1 or LePG alone did not significantly increase fruit firmness. However, fruits suppressed for both LePG and LeExp1 expression were significantly firmer throughout ripening and were less susceptible to deterioration during long-term storage. Juice prepared from the transgenic tomato fruit with reduced LePG and LeExp1 expression was more viscous than juice prepared from control fruit.     

Changes in pectins and product consistency during the concentration of tomato juice to paste

Concentrating tomato juice to paste during the tomato season allows for preservation and long-term storage, but subsequent dilution for formulation of value-added products is known to result in a loss of consistency. To understand the reasons for this, samples of unconcentrated juice, processing intermediates, and concentrated paste were collected from an industrial processing plant during normal commercial production. All samples were diluted with water to 5 degrees Brix and then analyzed for consistency and pectin content. Whole juice consistency, measured with a Bostwick consistometer, decreased through the course of juice concentration, with the largest change occurring early in the process, as the juice was concentrated from 5 to 10 degrees Brix. This decrease in consistency occurred during the production of paste from both hot- and cold-break juices. The change in Bostwick value was correlated with a decrease in the precipitate weight ratio. The loss of consistency during commercial processing was not the direct result of water removal because a sample of this same 5 degrees Brix juice could be concentrated 2-fold in a vacuum oven and then diluted back to 5 degrees Brix with no change in consistency or precipitate ratio. Total pectin content did not change as the juice was concentrated to paste, but the proportion of the total pectin that was water soluble increased. The greatest increases in pectin solubility occurred during the hot break and late in the process where the evaporator temperature was the highest.     

Changes in antioxidant and metabolite profiles during production of tomato paste

Tomato products and especially concentrated tomato paste are important sources of antioxidants in the Mediterranean diet. Tomato fruit contain well-known antioxidants such as vitamin C, carotenoids, flavonoids, and hydroxycinnamic acids. The industrial processing of this fruit into tomato paste involves several treatments that potentially affect the final profile of antioxidants and other metabolites in the commercial product. Here we have used both biochemical and metabolomic techniques to assess the effect of each separate step in the industrial production chain starting from fresh fruit to the final tomato paste. Material was collected from five independent tomato paste production events spread over two successive years. Samples comprised the intact ripe fruits and semifinished products after fruit-breaking, separation of the pulp from skin and seeds, evaporation, and finally after canning and pasteurization. The effect of each processing step was determined by different types of analysis. First, the total antioxidant capacity and total phenolic content were determined by commonly used spectrophotometric methods. Second, individual antioxidants in the extracts were identified and compared using an HPLC with online antioxidant detection. Third, in each sample the levels of the major individual antioxidants present, i.e., vitamin C, phenolic compounds (such as rutin and chlorogenic acid), tocopherols, and carotenoids, were quantified. Fourth, an untargeted metabolomic approach using LC-QTOF-MS was used to identify those production steps that have the largest impact on the overall metabolic profile in the final paste as compared to the original fruits. This multifaceted approach has revealed that each processing step induces specific alterations in the metabolic profile, as determined by the different analysis procedures, and that in particular the fruit-breaking step and the removal of seed and skin significantly affect the levels of antioxidants and many other metabolites present in commercial tomato paste.     

Rheological characterization of a novel functional food: tomato juice with soy germ

The rheological properties of tomato juice containing 1.5% soy germ were compared to plain tomato juice with and without soy protein isolate. This novel product was developed to provide a delivery system of carotenoids, soy protein, and significant isoflavone content without compromising the perceived juice characteristics of tomato product. Rheological tests depicted physical gel characteristics for all three products. Dynamic tests as a function of temperature showed that the stability and the compatibility between tomato juice and soy germ were higher as compared to soy protein isolate. The hydrophobic and electrostatic interactions between pectin and protein in the tomato soy protein isolate system were weakened as the temperature was increased. In the case of tomato juice with soy germ, the viscosity did not change during heating. The addition of soy germ increased the viscosity of tomato juice reinforcing the entire system without major qualitative effects on the rheological properties of plain tomato juice.     

Occurrence of flavonols in tomatoes and tomato-based products

The flavonol contents of 20 varieties of tomato fruit were investigated in relation to variety, size, season, and country of origin. Ten commonly consumed tomato-based food products were also assessed. Free and conjugated flavonols were identified and quantified using reversed-phase HPLC. Ninety-eight percent of flavonols detected in tomatoes were found to occur in the skin. Tomatoes contained, primarily as conjugates, quercetin and kaempferol. The main quercetin conjugate was identified as rutin (quercetin 3-rhamnosylglucoside) by LC-MS. The total flavonol content of the different varieties of tomato that were analyzed varied from 1.3 to 22.2 microgram/g of fresh weight (fw). Smaller cherry tomato fruits originating from warm sunny climates, such as Spain and Israel, were found to contain the highest concentration of flavonols. Among the tomato-based products investigated, tomato juice and tomato purée were rich in flavonols, containing 14-16 microgram/mL and 70 microgram/g fw, respectively. In contrast to fresh tomatoes, most tomato-based products contained significant amounts of free flavonols.     

超表达亚硫酸氧化酶基因对促进番茄果实亚硫酸盐氧化的研究

本研究以亚硫酸氧化酶基因（SO）超表达系（OE）、干扰系（Ri）及野生型（WT）的绿熟番茄果实为材料,经SO2熏蒸后,12℃低温贮藏,研究亚硫酸氧化酶基因的超表达,对番茄贮藏期间相对电导率、亚硫酸盐含量、番茄红素含量及成熟度的变化。结果表明,经SO2熏蒸后,Ri果实较WT果实表现为相对电导率增加,亚硫酸盐残留较多,番茄...     

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。     

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.     

Optimizing sampling of tomato fruit for carotenoid content with application to assessing the impact of ripening disorders

Color defines one aspect of quality for tomato and tomato products. Carotenoid pigments are responsible for the red and orange colors of tomato fruit, and thus color is also of dietary interest. The aims of this study were (1) to determine the relative importance of field sampling and analytical replication when measuring lycopene and beta-carotene in tomato fruit and (2) to determine the effect of yellow shoulder disorder (YSD) on the content of lycopene and beta-carotene in tomato juice and tissue. Our results show that increasing biological replications is an efficient strategy for reducing the experimental error associated with measurements of lycopene and beta-carotene. Analytical replications did not contribute significantly to observed variation, and therefore experimental efficiency will be gained by reducing analytical replications while increasing field replication. We found that YSD significantly reduces lycopene in affected tissue and in juice made from affected fruit. In contrast, beta-carotene concentrations were only reduced in affected tissue but were not significantly reduced in juice. With increasing interest in biofortified crops, modulating the carotenoid profile in tomato by minimizing YSD symptoms represents a strategy for improving tomato fruit quality that is currently supported by grower contract structure and processor grades.     

The effects of silicon on nutrient levels and yields of tomatoes under saline stress in artificial medium culture

The purpose of this study was to determine the effects of silicon on the stem + leaf dry weight, fruit yield, quality and nutrient levels of tomatoes, cultured under saline stress on an artificial medium. Silicon doses (0, 0.5, 1.0, 2.0 mM) were combined in nutrient solution with 0, 44.4 and 70.4 mM NaCl in a factorial experiment with three replications. All silicon concentrations without NaCl increased stem + leaf dry weight and 1.0 mM Si increased fruit yield. Silicon increased fruit yield at 44.4 mM NaCl and steam + leaf dry weight at high NaCl concentrations. NaCl significantly increased the level of soluble solids in fruit and decreased the pH of fruit juice. Silicon significantly increased the pH of the tomato juice and decreased the number of fruits at high concentrations of NaCl. The effects of NaCl, Si and their interaction on nutrient contents and Si levels in leaves were statistically significant at different concentrations.     

Tetrahydro-beta-carboline alkaloids occur in fruits and fruit juices. Activity as antioxidants and radical scavengers

Tetrahydro-beta-carbolines are biologically active alkaloids that occur and accumulate in mammalian tissues, fluids, and brain, but their ultimate origin or biological role is still uncertain. Four tetrahydro-beta-carboline alkaloids: 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid, 1-methyl-1,2,3,4-tetrahydro-beta-carboline, and 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline, are found as naturally occurring substances in some fruit and fruit juices. These compounds occur in the microg/g level in those products, and a characteristic and distinct profile appears to exist depending on the type of fruit and juice involved. Thus, 1-methyl-1,2,3,4-tetrahydro-beta-carboline may appear in tomato, tomato juice, and kiwi; 6-hydroxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline in bananas, pineapple, tomato, and their corresponding juices; and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid in oranges and grapefruits, although it also occurred in most juices. Fruit-occurring tetrahydro-beta-carboline alkaloids acted as antioxidants and free radical scavengers in the ABTS assay when compared with ascorbic acid and Trolox. This suggests that tetrahydro-beta-carboline alkaloids might act as antioxidants when absorbed and accumulated in the body, contributing to the antioxidant effect of fruit products containing these compounds.     

Carotenoid pigmentation affects the volatile composition of tomato and watermelon fruits, as revealed by comparative genetic analyses

Tomato near-isogenic lines differing in fruit carotenogenesis genes accumulated different aroma volatiles, in a strikingly similar fashion as compared to watermelon cultivars differing in fruit color. The major volatile norisoprenoids present in lycopene-containing tomatoes and watermelons were noncyclic, such as geranial, neral, 6-methyl-5-hepten-2-one, 2,6-dimethylhept-5-1-al, 2,3-epoxygeranial, (E,E)-pseudoionone, geranyl acetone, and farnesyl acetone, seemingly derived from lycopene and other noncyclic tetraterpenoids. Beta-ionone, dihydroactinodiolide, and beta-cyclocitral were prominent in both tomato and watermelon fruits containing beta-carotene. Alpha-ionone was detected only in an orange-fleshed tomato mutant that accumulates delta-carotene. A yellow flesh (r) mutant tomato bearing a nonfunctional psy1 gene and the yellow-fleshed watermelon Early Moonbeam, almost devoid of carotenoid fruit pigments, also lacked norisoprenoid derivatives and geranial. This study provides evidence, based on comparative genetics, that carotenoid pigmentation patterns have profound effects on the norisoprene and monoterpene aroma volatile compositions of tomato and watermelon and that in these fruits geranial (trans-citral) is apparently derived from lycopene in vivo.     

猪血蛋白水解物对盆栽樱桃番茄生长和品质的影响

  【目的】  研究外源喷施不同浓度猪血蛋白水解物 (PP)对樱桃番茄植株生长和品质的影响,以期为高产优质樱桃番茄生产提供理论参考。  【方法】  以樱桃番茄品种“盆栽红”为试验材料,采用基质栽培,设置3个PP浓度:0 g/L (CK)、1 g/L (PP1)、2 g/L (PP2),在开花期进行叶面喷施,整个生育期共喷施6次。樱桃番茄在第三穗果实完全成熟后收获,分析外源PP对樱桃番茄植株生长、光合作用、养分吸收以及果实品质的影响。  【结果】  PP1和PP2处理不同程度地增加了番茄地上部、根部以及果实中氮、磷、钾含量,显著提高了叶片叶绿素含量、净光合速率 (Pn)、蒸腾速率 (Tr)和气孔导度 (Gs),植株地上部鲜重比CK处理分别增加了18.2%和40.6%,干重分别增加了42.3%和57.4%,且PP2处理的效果好于PP1处理。与CK处理相比,PP2处理番茄的产量、单果重、横径、纵径和硬度分别增加了37.4%、26.6%、16.3%、10.3%和30.8%,并有效改善了果实色泽,提高了樱桃番茄的外观品质。PP2处理有利于樱桃番茄果实中可溶性糖、可溶性蛋白、抗坏血酸和谷胱甘肽的积累,较CK分别增加了24.2%、25.5%、96.6%和30.9%;番茄果实中的总酚、类黄酮和花色素苷含量分别增加18.7%、33.3%和56.2%,DPPH自由基清除能力和铁还原抗氧化能力分别增加了27.7%和29.4%,显著提高了番茄果实的抗氧化活性。  【结论】  外源喷施2 g/L的猪血蛋白水解物能有效改善番茄植株的养分吸收和光合作用,促进植株生长和番茄品质的提升,是一种提高樱桃番茄产量、改善营养和功能性品质的高效有机措施。     

Gas chromatographic determination of fenvalerate insecticide residues in processed tomato products and by-products

The results of a 5-laboratory collaborative determination of residues of the synthetic pyrethroid insecticide fenvalerate in tomato products are presented. Tomatoes from plants treated in the field at 2-4 day intervals (13 foliar applications) were processed into chopped fresh tomatoes, canned quarters, juice, paste, and the by-product skins plus seeds. Gas chromatographic analysis of the commodities for fenvalerate showed the fresh produce to contain 0.26 ppm, and the skins plus seeds contained 1.9 ppm. Residues were barely detectable in canned peeled quarters and juice, but averaged 0.12 ppm for paste, the concentration product of juice. High residues were associated with the skin content of the product. Five laboratories using modifications of the same analytical technique obtained good collaborative agreement.     

Processing effects on lycopene content and antioxidant activity of tomatoes

Consumption of tomato products has been associated with decreased risk of some cancer types, and the tomato antioxidant, lycopene, is thought to play an important role in the observed health effects. In this study, four carotenoids, trans-lycopene, phytofluene, phytoene, and zeta-carotene, were quantified in tomato products. Samples of raw tomatoes, tomato juice after hot break scalder, and final paste were obtained from two different processing plants over two years. Comparison of carotenoid levels throughout processing indicated that lycopene losses during processing of tomatoes into final paste (25-30 degrees Brix) ranged from 9 to 28%. The initial Brix level of the raw tomatoes appeared to influence the amount of lycopene loss that occurred, possibly due to the differences in processing time required to achieve the final desired Brix level of the paste. In general, no consistent changes in the other carotenoids were observed as a function of processing. The antioxidant activity of fresh tomatoes, tomato paste, and three fractions obtained from these products (i.e., aqueous, methanol, and hexane fractions) was also determined. In both a free radical quenching assay and a singlet oxygen quenching assay, significant antioxidant activity was found in both the hexane fraction (containing lycopene) and the methanol fraction, which contained the phenolic antioxidants caffeic and chlorogenic acid. The results suggest that in addition to lycopene, polyphenols in tomatoes may also be important in conferring protective antioxidative effects.     

加工型番茄果实硬度特异材料的果实特性及果肉组织特征

为能分析不同硬度加工番茄品系的果实特性和果肉组织特征差异,该文以田间发现的特异高硬度果实材料WT-75和WT-76为研究对象,分析了果实的可溶性固形物、总酸、番茄红素、单果耐压力、果肉组织含水量和可溶性果胶等主要品质指标差异,并利用石蜡切片和扫描电镜技术,研究不同材料间的果肉组织特征差异.结果表明,相较于对照ZH-10较软的手捏感官硬度评价,WT-75和WT-76的评价为特硬.利用平板挤压法测试硬度,WT-75和WT-76的耐压力分别为79.70和77.71 N,极显著高于(P＜0.01)对照ZH-10的耐压力.在测试的果实主要品质指标中,WT-75和WT-76的可溶性果胶含量显著高于(P＜0.05)对照ZH-10,其他的品质指标在各研究材料间不存在差异的显著性(P＞0.05).WT-75和WT-76的果肉组织石蜡切片结果表明,在200 μm视野下WT-75和WT-76的平均果肉细胞面积分别为0.037 6和0.053 2 mm2明显(P＜0.01)小于ZH-10(果肉细胞面积为0.089 9 mm2),且排列紧密.常温放置35d后,WT-75的果实腐烂率达93％,而对照ZH-10腐烂率为64％,WT-76的腐烂率为33％,ZH-10和WT-76的腐烂程度小于(P＜0.05)WT-75.结合与果肉组织的扫描电镜结果,相较对照ZH-10和WT-76,WT-75的果皮中分布了大量的小皮孔,这种果皮结构的特异性可能是导致果实的耐贮藏性显著降低的主要原因.通过对特异果实硬度加工型番茄果实主要品质、果肉组织特征和常温耐贮藏性研究,为后期适宜加工型番茄杂交品种亲本的选配筛选提供理论依据.     

Carotenoid profiling and biosynthetic gene expression in flesh and peel of wild-type and hp-1 tomato fruit under UV-B depletion

Although light is recognized as one of the main factors influencing fruit carotenogenesis, the specific role of UV-B radiation has been poorly investigated. The present work is addressed to assess the molecular events underlying carotenoid accumulation in presence or absence of ultraviolet-B (UV-B) light in tomato fruits of wild-type and high pigment-1 (hp-1), a mutant characterized by exaggerated photoresponsiveness and increased fruit pigmentation. Gene expression analyses indicated that in wild-type fruits UV-B radiation mainly negatively affects the carotenoid biosynthetic genes encoding enzymes downstream of lycopene both in flesh and peel, suggesting that the down-regulation of genes CrtL-b and CrtL-e and the subsequent accumulation of lycopene during tomato ripening are determined at least in part by UV-B light. In contrast to wild-type, UV-B depletion did not greatly affect carotenoid accumulation in hp-1 and generally determined minor differences in gene expression between control and UV-B-depleted conditions.     

Enzyme immunoassay for tenuazonic acid in apple and tomato products

The Alternaria mycotoxin tenuazonic acid was derivatized with succinic anhydride and conjugated to keyhole limpet hemocyanin (KLH) and to horseradish peroxidase (HRP), respectively. The KLH conjugate was used to produce polyclonal antibodies in rabbits. A competitive direct enzyme immunoassay (EIA) for tenuazonic acid was established, which was moderately sensitive for tenuazonic acid [50% inhibition concentration (IC(50)): 320 ± 130 ng/mL] but strongly reacted with tenuazonic acid acetate (IC(50): 23.3 ± 7.5 ng/mL). Therefore, an optimized EIA protocol was established, which employed acetylation of standard and sample extract solutions. The mean standard curve detection limit (IC(30)) for tenuazonic acid acetate was 5.4 ± 2.0 ng/mL, enabling detection limits for tenuazonic acid in apple and tomato products of 25-50 ng/g (150 ng/g in tomato paste). Recoveries in a concentration range of 50-2000 ng/g were 60-130% in apple juice and tomato juice and 40-150% in other tomato products. Tenuazonic acid was detected in apple juice and tomato products from German retail shops at levels of 50-200 ng/g. In conclusion, this novel EIA for tenuazonic acid could be useful within a screening program for Alternaria mycotoxins in food.