Profiling shifts in protein complement in tomato fruit induced by atmospheric ozone-enrichment and/or wound-inoculation with Botrytis cinerea

To unravel the mechanism by which low level atmospheric ozone-enrichment (0.05 μmol mol⁻¹) increases the shelf-life of tomato fruit (Lycopersicon esculentum Mill.) by suppressing the growth of pathogens (Botrytis cinerea), protein yield and composition were examined during and following exposure to the gas at 13 °C/95% RH. Ozone-enrichment caused marked changes in protein yield and composition in control tomato fruit and suppressed shifts in the proteome induced by wounding/fungal attack. Wound/fungal-inoculation with B. cinerea resulted in a 7% increase in protein yield, and the down-regulation of at least 32 proteins. A number of proteins affected under ozone and wound/fungal-inoculation treatments are involved in the control of cellular oxidative status. Proteins that may be enhanced under oxidative stress were induced during ozone exposure (e.g. thioredoxin peroxidase-TPX), but suppressed following transfer to ‘clean air’ (e.g. ascorbate peroxidase-APX1). Constitutively-expressed proteins tended to increase reversibly under ozone-treatment, however proteins involved in ripening such as an enzyme related to ethylene biosynthesis (1-aminocyclopropane-1-carboxylate oxidase-ACO) were markedly reduced in ozone-treated tomato fruit but increased in wound-inoculated fruit. Levels of proteins involved in carbohydrate metabolism, pentose phosphate pathway, terpenoid and flavonoid biosynthesis differentiated among the treatments. The presented dataset makes a central contribution to a comprehensive analysis of the manner in which tomato fruit react to ozone-enrichment and/or pathogen infection during storage/transit.     

Impact of yield and quality-related traits of sugarcane on sugar recovery

Sugar recovery of Pakistani sugarcane varieties is relatively low as compared to the rest of the world while very little work is done on this aspect. The current study was conducted to tackle this issue and to assess the effect of quality and yielding traits on final sugar recovery. Sixty genotypes of sugarcane were sown during 2013 and data was collected at different growth stages during maturity and post maturity. Correlation studies indicated that polarity (0.77**) and purity (0.73**) were positively and significantly correlated with sugar recovery while brix% (-0.21**), fiber contents (-0.21**) and number of leaves per plant (-0.33**) were significant and negatively correlated with sugar recovery. Furthermore, leaf area was positively and significantly correlated with internode length (0.63**). Path coefficient analysis indicated that highest direct effect on sugar recovery was shown by purity (2.92), followed by brix% (2.48), and leaf area (0.66) which confirms that these traits could contribute more towards an increase of sugar recovery. Overall values of higher direct and indirect effects were observed by purity. The results of the current studies indicate that sugar recovery can be improved by focusing on purity, brix%, and leaf area.     

Effect of antifungal hydroxypropyl methylcellulose-beeswax edible coatings on gray mold development and quality attributes of cold-stored cherry tomato fruit

Edible composite coatings based on hydroxypropyl methylcellulose (HPMC), beeswax (BW), and food preservatives with antifungal properties, were evaluated on cherry tomatoes during cold storage. Food preservatives selected from previous research work included sodium propionate (SP), potassium carbonate (PC), ammonium phosphate (APh) and ammonium carbonate (AC). Cherry tomatoes artificially inoculated with Botrytis cinerea were coated and stored up to 15 d at 5 °C followed by 7 d of shelf-life at 20 °C. All antifungal HPMC-BW coatings significantly reduced gray mold development on inoculated and cold-stored cherry tomatoes, the SP-based coating being the most effective. Analytical and sensory fruit quality was also evaluated after cold storage and shelf-life. The AC-based coating was the most effective to control weight loss and maintain the firmness of coated cherry tomatoes. Respiration rate, firmness, color, sensory flavor, off-flavor, and fruit appearance were not adversely affected by the application of the antifungal coatings. Overall, the application of HPMC-BW edible composite coatings containing AC could be a promising treatment to extend the postharvest life of cherry tomatoes. Further studies should focus on the modification of some physical characteristics of the coatings in order to enhance the general performance and provide higher peel gloss.     

Biomechanical characteristics of tomato fruit peels

Mechanical properties, such as strength and elasticity, of tomato peel (exocarp) are important in fruit used both for industrial processing and for fresh consumption, and, therefore, are also of vital interest to breeders. The food industries prefer peel to be thick and stiff for easy peeling, whereas consumers of fresh produce prefer thin, soft peel, for easy eating. The various varieties of tomato fruit genetically developed by breeders might exhibit the desired quality or biomechanical characteristics, but at the same time, might produce types of peel that do not always meet the requirements of the canneries or the fresh-fruit market. The present study evaluated the morphology and mechanical characteristics of the fruit skin and its integrated cuticular membranes, and determined their suitability for industrial processing and/or human consumption. The biomechanical and anatomical properties of fruit peels of five tomato (Lycopersicon esculentum) cultivars were investigated. The mechanical properties of ripe tomato peel under axial tension were characterized by measuring strength, elastic modulus, failure stress, overall stiffness and degree of stiffening, by means of deformation and puncture testing of flat strip and circular disk samples, respectively, with a Universal Testing Machine. Data were collected by two testing methods for each peel sample from up to 15 fruit of each of five cultivars. The results were analyzed statistically to determine the instantaneous elastic strains, breaking stress (strength), and work of fracture the peels. The overall stiffness and the extent to which the stress–strain curve deviated from a straight line were calculated. The results suggested a standard measure for each tomato variety, based on its mechanical integrity and suitability for processing or fresh consumption.     

Effect of oxalic acid on ripening attributes of banana fruit during storage

The effect of exogenous oxalic acid treatment on ripening attributes of banana fruit during storage was investigated. Banana fruit were dipped into solutions of 0 (control) or 20 mM oxalic acid for 10 min and then stored at room temperature (23 ± 2 °C) and 75–90% relative humidity. The application of oxalic acid reduced fruit deterioration during storage. The oxalic acid treatment also reduced the rates of respiration and ethylene production, and delayed the decreases in firmness, hue angle, and maximal chlorophyll fluorescence (Fv/Fm) of banana fruit during storage. Furthermore, fruit treated with oxalic acid exhibited higher superoxide dismutase activity and antioxidant capability with a lower production of reactive oxygen species at the late storage period compared with non-oxalic acid-treated fruit. Overall, the oxalic acid treatment was effective in inhibiting postharvest ripening of banana fruit and exhibited the potential for commercial application to store the bananas at room temperature. It can be concluded that the delay in banana fruit ripening associated with oxalic acid treatment could be due to inhibition of respiration and ethylene production rates, and reduction of oxidative injury caused by reactive oxygen species through increased antioxidant activity.     

番茄种质资源果实性状遗传趋势研究

摘 要：研究番茄种质资源形态学性状遗传趋势,以期了解其多样性状况、亲缘关系,为我国番茄资源的开发利用提供理论依据。以50尖黄,47(A-6t),93-29,A33-1,46(A-10t),93-11,A-17,49(7-1t),48(7t) 9种不同的番茄品种及杂种F1代群体植株为实验材料,对杂交亲本及杂种F1代的坐果率、单果重、果型指数等性状进行遗传趋势分析。通过杂交育种可以改变番茄的部分形态性状,从而提高番茄的产量、品质及其抗性。     

Effect of wounding on cell wall hydrolase activity in tomato fruit

Changes in the activity of the cell wall hydrolases – polygalacturonase (EC 3.2.1.15), pectinesterase (EC 3.2.1.11) and β-galactosidase (EC 3.2.1.23) – have been investigated following wounding of tomato fruit pericarp tissue (Lycopersicon esculentum cv. Ailsa Craig). In ripening fruit wounding appears to arrest the further synthesis of polygalacturonase. β-Galactosidase synthesis may also have been arrested in ripening fruit. The level of pectinesterase declined over the first 24 h following harvest, and since this was apparent in both wounded and unwounded tissue may be related to a harvest, rather than a wounding effect. There was a recovery of activity in intact fruit by 48 h after harvest but this seems to be impaired in wounded tissue. In the case of pectinesterase, this observation was extended to examine the changes in isoform profile and it appeared that the decline of this enzyme may be associated with the reduction of one specific isoform — PE2. In contrast to ripening fruit, wounding of fruit at the fully ripe stage appears to have no significant effects on the activities of any of these three enzymes.     

Effect of hyperbaric pressure and temperature on respiration rates and quality attributes of tomato

Previous work with hyperbaric treatment of tomato focused on application at lower temperature (13 °C). In this work, hyperbaric treatment at varying pressure levels (i.e., 0.1, 0.3, 0.5, 0.7 and 0.9 MPa) at ambient temperature (20 °C) was tested as a potential alternative to conventional refrigerated storage (0.1 MPa at 13 °C) to preserve tomato quality. The experiments were divided into 3 phases: (1) 4 day of hyperbaric treatment, (2) 5 day of post-treatment ripening, and (3) 10 day of post-treatment ripening. Respiration rate (RR) of the tomatoes was continuously monitored during the course of the hyperbaric treatments. Quality attributes were assessed immediately after removal from the hyperbaric treatments and after 5 and 10 day ripening at 20 °C after removal from the treatments. Hyperbaric treatments at ≥0.3 MPa resulted in RR equal or higher than the RR in control fruit (0.1 MPa at 20 °C). The lowest RR was obtained from tomato stored at 0.1 MPa at 13 °C. Hyperbaric treatment at 0.5, 0.7 and 0.9 MPa significantly reduced weight loss, retained color, firmness, total soluble solid (TSS), titratable acidity (TA) and TSS:TA ratio at similar levels as the tomato treated at 13 °C and 0.1 MPa. Firmness after treatment was highest for fruit from 0.1 MPa at 13 °C and from 0.5, 0.7 and 0.9 MPa at 20 °C. The higher firmness advantage declined by 5 day of ripening after treatment, with higher firmness only being retained for fruit from the 0.9 MPa at 20 °C and the 0.1 MPa at 13 °C treatments. After 10 day ripening, firmness was similar for all treatments. Lightness (L*) and hue angle were greater for all treatments compared with the 0.1 MPa at 20 °C treatment. However, only the greater hue angle difference was maintained after 5 day of ripening. After 10 day ripening, no significant differences were found in color attributes. Only 0.1 MPa at 13 °C retained higher soluble solids, lower titratable acidity and higher TSS:TA ratios after treatment and after 5 day ripening. At 10 day of ripening none of the quality attribute differences noted were retained for any of the treatments. These results show that the only consistent effect of hyperbaric treatment at 0.5, 0.7 and 0.9 MPa was to reduce weight loss and enhance firmness retention up to 5 day ripening after treatment.     

Resistance of tomato cultivars and progenies to fruit hollowness

Summary In field experiments with fall and winter tomatoes, the incidence of fruit hollowness was found to range from 0 to more than 80%, depending both on the cultivar and the environment. The most resistant cultivars were Bonner Beste and Potentate; the most susceptible were Exhibiton, Moneymaker, E.S. 1, Berco, Cromco and Ailsa Craig. The rate of hollowness of F₁ and F₂ generations of crosses between resistant and susceptible parents suggests that resistance behaves as a partially dominant character governed by a small number of genes. Thus, commercial F₁ hybrids resistant to the disorder are easy to produce. The heritability of the resistance character was found to be rather high.Contribution from The Volcani Institute of Agricultural Research, Bet Dagan, Israel. 1969 Series, No. 1558-E.     

Diffusivity of 1-methylcyclopropene in spinach and bok choi leaf tissue,disks of tomato and avocado fruit tissue,and whole tomato fruit

Gaseous 1-methylcyclopropene (1-MCP) has been widely employed for delaying ripening and senescence of harvested fruit and vegetables; however, details on ingress of gaseous1-MCP in plant tissues, which might contribute to differences in responsiveness of different horticultural commodities to 1-MCP, have not been reported. In this study, we used spinach and bok choi leaves, disks from tomato epidermis, stem-scar and avocado-exocarp tissues, and whole tomato fruit to examine ingress of gaseous 1-MCP. Using a dual-flask system, equilibration of 20 μL L⁻¹ (831 μmol m⁻³) 1-MCP through leaf tissue was reached within 1–2 h, and paralleled 1-MCP transfer through glass-fiber filter paper. For disks derived from fruit tissues, changes in 1-MCP concentrations in the dual-flask system showed anomalous patterns, declining as much as 70% in source flasks with negligible accumulation in sink flasks. The pattern of 1-MCP distribution was markedly different from that of ethylene, which approached equal distribution with tomato stem-scar and avocado exocarp but not tomato epidermis tissues. 1-MCP ingress was further addressed by exposing whole tomato fruit to 20 μL L⁻¹ 1-MCP followed by sampling of internal fruit atmosphere. Tomato fruit accumulated internal gaseous 1-MCP rapidly, reaching approximately 8–9 μL L⁻¹ within 3–6 h at 20 °C. Internal 1-MCP concentration ([1-MCP]) declined around 74 and 94% at 1 and 3 h after exposure, respectively. Ingress was similar at all ripening stages and reduced by 45% in fruit coated with commercial wax. Blocking 1-MCP ingress through stem- and blossom-scar tissues reduced accumulation by around 60%, indicating that ingress also occurs through epidermal tissue. Fruit preloaded with 1-MCP and immersed in water for 2 h retained about 45% of post-exposure gaseous [1-MCP], indicating that 1-MCP is not rapidly sorbed or metabolized by whole tomato fruit. Rapid ingress of gaseous 1-MCP was also observed in tomato fruit exposed to aqueous 1-MCP. Both accumulation and post-exposure decline in internal gaseous [1-MCP] are likely to vary among different fruit and vegetables in accordance with inherent sorption-capacity, surface properties (e.g., waxes, stoma), volume and continuity of gas-filled intercellular spaces, and tissue hydration.     

番茄果实总RNA提取与cDNA-AFLP

从番茄果实中提取高质量的RNA是对调控番茄果实品质、生长发育和代谢等相关基因进行分子生物学研究的基础。实验表明,已报道的相关RNA的提取方法,即使利用已经报道的从其它果实中成功提取出高质量RNA的方法,也不能从番茄果实中分离出高质量的RNA。 这主要是由于番茄果实中多糖、多酚类物质及其他次生代谢,在RNA提取过程中与RNA共同沉淀,从而影响RNA的产量和质量。目前,商业化的RNA抽提试剂盒无法直接用于番茄果实RNA的提取。笔者采用4种方法对番茄果实总RNA进行提取,筛选出一种最佳的改进方法。可以从不同时期番茄果实中成功提取高质量的RNA,产量可达401.6--840.2μg/g,通过测定A260/A230和A260/A280 的比值表明,该方法排除了番茄果实中蛋白、多糖、以及多酚等次生物质的干扰,提取到了高质量番茄果实总RNA;1.2%琼脂糖电泳结果表明RNA在整个提取过程中结构完整,未发生明显降解;所提取的RNA用于cDNA-AFLP等到了清晰的表达图谱,这表明其质量完全可满足下一步分子生物学研究。     

Improving tomato fruit quality and the european regulatory framework

Tomato fruit quality is determined by a complex set of characters. Fruit used by the fresh market industry must have different attributes than those used by the processing industries. We have determined the major targets of the tomato industry and have isolated from the tomato itself genes which based upon their biochemical function are expected to improve texture and rheology, colour, soluble solids and flavour. Our research is aimed at proving this concept. So far we have demonstrated that polygalacturonase (PG) is a major fruit quality gene providing the processing tomato industry with improved viscosity. Commercial tomato hybrids have been developed in collaboration with Petoseeds (USA) which carry this effect gene. The regulatory system in Europe will be reviewed. Field trials are covered by the EC directive 90/220, which has now been implemented by all countries belonging to the European Union. On the contrary there are no European-wide regulations in place to cover the production of genetically modified plants as food sources. The evolving food regulations will be reviewed and evaluated in the context of competitiveness of the European plant biotechnology industry.     

采后UV-C辐照对番茄果实基因表达谱的短时效应

利用美国昂飞公司的番茄基因芯片进行微阵列分析,从而对经UV-C(4 kJ/m2)辐照后贮藏24 h内的番茄果实中的基因表达情况作出全面概括。结果表明,经UV-C辐照的番茄果实中分别有274和403个基因发生了基因上调和下调,比对照果实高出两倍多。发生上调的基因主要涉及到信号转导、防御反应及生理代谢功能;与之相反,一些涉及到细胞壁降解、光合作用及脂类代谢功能的基因则普遍发生基因下调。本研究结果从分子机制的角度阐述了采后UV-C辐照使番茄果实抗病性增强、延迟软化、维持采后品质及延长贮期的原因。     

Penalized regression techniques for modeling relationships between metabolites and tomato taste attributes

The search for models which link tomato taste attributes to their metabolic profiling, is a main challenge within the breeding programs that aim to enhance tomato flavor. In this paper, we compared such models calculated by the traditional statistical approach, stepwise regression, with models obtained by the new generation of regression techniques, known as penalized regression or regularization methods. In addition, for penalized regression, different scenarios and various model selection criteria were discussed to conclude that classical crossvalidation, selects models with many superfluous variables whereas model selection criteria such as Bayesian information criterion, seem to be more suitable, when the goal is to find parsimonious models, to explain tomato taste attributes based on metabolic information. An exhaustive comparison of the discussed methodology was done for six sensory traits, showing that the most important covariates were identified by the stepwise regression as well as by some of the penalized regression methods, despite the general disagreement on the size of the regression coefficients between them. In particular, for stepwise regression the coefficients are inflated due to their high variance which is not the case with penalized regression, showing that this new methodology, can be an alternative to obtain more accurate models.     

Deployment of low-level ozone-enrichment for the preservation of chilled fresh produce

Tomatoes, strawberries, table grapes and plums were inoculated with Botrytis cinerea (grey mould), transferred to chilled storage (13 °C) and exposed to ‘clean air’ or low-level ozone-enrichment (0.1 μmol mol⁻¹). Ozone-enrichment resulted in a substantial decline in spore production as well as visible lesion development in all treated fruit. Exposure-response studies performed specifically on tomato fruit (exposed to concentrations ranging between 0.005 and 5.0 μmol mol⁻¹ ozone) revealed lesion development and spore production/viability to be markedly reduced in produce exposed to ozone prior to, or following, infection with B. cinerea; higher concentrations/duration of exposure yielding greater reductions in lesion development and spore production/viability. Impacts on Botrytis colonies grown on Potato Dextrose Agar (PDA) for 5–6 days at 13 °C and 95% relative humidity (RH) revealed less effects than studies on fruit inoculated with the pathogen in vivo. Taken as a whole, the results imply that ozone-induced suppression of pathogen development is due, to some extent, to impacts on fruit–pathogen interactions. This work suggests that ozone may constitute a desirable and effective residue-free alternative to traditional postharvest fungicide practices. Data presented illustrate that optimal ozone treatment regimes are likely to be commodity-specific and require detailed investigation before such practices can be contemplated commercially.     

日光温室越冬番茄果实干物质生产分析

实际生产中,温室番茄果实产量是由各果穗产量构成的,并由分配到各果穗中的干物质量来决定的,分析各果穗的干物质生产规律有助于了解整株果实生产的动态。本试验采用了果穗和果穗下的三片叶及对应的茎作为一个源库生长单位的研究方法,详细研究了越冬温室番茄果实干物质生产规律,研究结果表明：叶面积指数在定植三个月之内几乎呈直线增加,达到3.3,之后随打叶和叶片生长维持在2.6左右;植株干物质累积明显地分为缓慢积累阶段和快速积累阶段,生长202天后,干物质累积达到1.6kg/m2;植株座果后,地上部干物质分配到果实的比例占到70%;源库生长单位的果实所分配到的干物质为98%-48%,随着果穗数从下而上的不断增加,在前七穗果同时存在的情况下,每产生一穗果实,各生长单位往果实的干物质分配就下降6%左右,这与果穗的库强有关,随着成熟果实的采收,干物质在新果穗的分配比例增加;除第一生长单位外,其余生长单位内茎、叶分配比均为3：7。     

Effects of chlorine dioxide treatment on respiration rate and ethylene synthesis of postharvest tomato fruit

Tomato fruit at the mature green stage were treated with ClO₂ gas in a sealed container for 12 h, and then stored at 23 °C with 85% relative humidity (RH) for 23 d. Respiration rate, respiration-related enzymes including phosphohexose isomerase (PHI), succinate dehydrogenase (SDH), and glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH), ethylene production, and the expression of LeAOX1a, LeCOX1, LeACS2, LeACS4 and LeACO1 genes were measured. The results showed that application of ClO₂ gas was effective in reducing total respiration, cytochrome pathway respiration and the expression of LeCOX1, but no significant reduction in the activities of respiration-related enzymes was observed during storage. Fruit treated with ClO₂ resulted in lower ethylene production. Furthermore, the expression of ethylene biosynthesis related genes, including LeACS2, LeACS4 and LeACO1 was reduced by the ClO₂ treatment. These results indicate that ClO₂ treatment might delay the ripening of tomato fruit, possibly by a mechanism involving suppression of respiration rate and ethylene biosynthesis.