Control of Monilinia rots on fruit naturally infected by hot water treatment in commercial trials

In recent years, safer methods for the control of fruit postharvest pathogens have been investigated and heat treatment could represent an effective and safe approach for managing postharvest decay such as Monilinia rots. In the present study, the effect of hot water treatment (HWT) (60 °C for 30 and 60 s) on brown rot was investigated. More specifically, the influence of HWT was determined in in vitro trials on conidial germination of Monilinia laxa, Monilinia fructicola and Monilinia fructigena and in peach and nectarine fruit, naturally infected. The effect of hot water application on fruit quality was also assessed. M. fructicola showed a greater resistance to heat than M. laxa and M. fructigena, however conidia germination of all three species was completely inhibited by a dipping in hot water for 1 min at 55 °C. The results of a large scale experiment under commercial conditions and several pilot trials showed a good antifungal activity of HWT in naturally infected fruit. After 6 days at 0 °C and 3 days at 20 °C, in both semi-commercial and commercial trials, the inhibition of decay was higher than 78% in four trials out of six. In addition, the treated fruit showed an acceptable commercial quality and no visual damage was observed as a consequence of HWT. The results demonstrated that HWT is a promising method to control Monilinia rots of peach and nectarine, and is safe and readily available for conventional and organic production under commercial conditions.     

水果醋中有机酸成分的分析

本文以陈醋作对照分析,采用气相色谱-质谱联用（GC-MS）对沙棘醋、柿子醋及苹果醋中的有机酸含量进行了分析测试。实验数据显示,果醋富含多种有机酸,以沙棘醋最多,共46种;柿子醋有25种;苹果醋32种;陈醋35种。果醋含有一些特殊的有机酸,具有较高的营养保健功效。     

Effects of a phospholipase D inhibitor on postharvest enzymatic browning and oxidative stress of litchi fruit

Membrane lipid degradation catalyzed by phospholipase D (PLD) results in postharvest browning and senescence of litchi fruit. The effects of n-butanol, a specific PLD inhibitor, on enzymatic browning and oxidative stress during storage of litchi fruit at room temperature were evaluated. n-Butanol-treated fruit had a lower browning index and disease index than untreated fruit. n-Butanol treatment also decreased PLD activity. As a result, the decompartmentalization of litchi polyphenoloxidase and substrates was reduced. The conversion of substrates (−)-epicatechin and procyanidin A₂ into quinones was slowed down and enzymatic browning of litchi pericarp tissues was lower after 6 d storage. Additionally, n-butanol-treated fruit possessed significantly lower malondialdehyde contents than untreated fruit after 4 d storage. Analysis of antioxidative enzyme activities showed that n-butanol treatment inhibited oxidative stress mainly by maintaining high catalase activity in litchi pericarp tissues. Consequently, senescence of litchi fruit during storage was moderated.     

The role of active oxygen metabolism in hydrogen peroxide-induced pericarp browning of harvested longan fruit

Effects of hydrogen peroxide (H₂O₂), as exogenous reactive oxygen, on browning and active oxygen metabolism in pericarp of harvested ‘Fuyan’ longan fruit were investigated. The results showed that as compared with the control fruit, there was a higher browning index in pericarp of H₂O₂-treated fruit. The fruit treated with H₂O₂ resulted in increased rate of superoxide anion (O₂⁻) production, reduced activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), decreased amounts of ascorbic acid (AsA), glutathione (GSH) and carotenoid, and increased malondialdehyde (MDA) content. These results indicated that H₂O₂-induced browning in pericarp of harvested longan fruit might be due to a reducing capacity of active oxygen scavenging and an increase of accumulation of O₂⁻, which might stimulate membrane lipid peroxidation, disrupt cellular membrane structure, and cause the loss of cellular compartmentalization, in turn, resulting in the contact of polyphenol oxidase (PPO) and peroxidase (POD) with phenolic substrates and subsequently oxidation phenolics to form brown polymers.     

Effect of genetic background on the target fatty acids of acyl-ACP thioesterase transgenes in Brassica napus

Acyl‐acyl carrier protein (ACP) thioesterase (TE) is involved in the biosynthetic fatty acid pathway of plants. Conventional canola lines transformed individually with the bay‐TE (Uc FatB1), elm‐TE (Ua FatB1), nutmeg‐TE (Mf FatB1) or Cuphea‐TE transgene (Ch FatB1), produce seed oil with modified fatty acid compositions. This study assessed the effects of genetic background, cytoplasm, maternal parent, and interaction of different TE transgenes, on the target fatty acids using F1 seeds and double haploid (DH) lines. The F₁ seeds were produced by crossing four TE transgenic parental lines and three non‐transgenic cultivars with distinct fatty acid compositions. The DH lines were developed from microspores of F₁ plants. DH lines from different crosses showed that genetic background does not have an effect on the relative levels of the target fatty acids of the same TE, indicating the stability of the substrate specificity of the TE within canola. However, significant effects of genetic background on the content of the major target fatty acids, lauric acid (C12:0) or palmitic acid (C16:0) depending on the TE, were observed. Expression of the TE in low erucic acid (C22:1) genotypes resulted in higher target fatty acid levels than expression in high C22:1 genotypes. Reciprocal crosses showed maternal effects, but not cytoplasmic effects. In addition, co‐expression of two different TE transgenes in the same seeds was observed. These results indicate the importance of selection for appropriate genetic backgrounds in order to maximize the expression of the target fatty acids of TE transgenes, and also indicate potential uses of TE co‐expression in modifying canola seed oil.     

Phomopsis longanae Chi-induced pericarp browning and disease development of harvested longan fruit in association with energy status

The effects of Phomopsis longanae Chi infection on browning development and disease incidence in relation to energy status in pericarp of harvested longan fruit were investigated. Longan fruit were inoculated for 5 min with P. longanae at 10⁴ spores mL⁻¹, while fruit dipped in sterile deionized water were used as control. These fruits were stored at (28 ± 1) °C and 90% relative humidity for up to five days. The results showed that the browning index, disease incidence, cellular membrane permeability and AMP content increased but the contents of ATP and ADP, and energy charge decreased in pericarp of longan fruit infected by P. longanae. It was suggested that P. longanae infection caused energy deficiency in longan fruit, possibly resulting in accelerated senescence and decreased resistance to pathogen, and thus promoted browning development and disease occurrence.     

Chilling-injury of harvested tomato (Solanum lycopersicum L.) cv. Micro-Tom fruit is reduced by temperature pre-treatments

Heat-shocks were used to reduce the development of chilling injury symptoms during ripening of tomato fruit (Solanum lycopersicum L. cv. Micro-Tom). Mature green tomatoes were immersed in 30-50 °C water for 3-9 min before being chilled at 2.5 °C for 0, 0.5, 1, 2, 3, or 14 days, and then held at 20 °C for an additional 7-14 days. The affect of both heat-shock and chilling treatments were independent of fruit weight. Measured at 20 °C after 14 days of chilling, fruit exposed to 40 °C for 7 min exhibited reduced chilling injury symptoms, as measured by their advanced ripening score and decreased rate of ion leakage into an isotonic 0.2 M mannitol solution. Reduced rates of leakage from the symplastic compartment probably contributed to the 2-fold decrease in the amount of ions in the apoplastic space, when compared to the control. A subsequent paper will report the results of metabolic profiling of Micro-Tom tomato fruit subjected to treatments that significantly decreased their development of chilling injury symptoms.     

Preharvest application of abscisic acid promotes anthocyanins accumulation in pericarp of litchi fruit without adversely affecting postharvest quality

Pericarp colour of litchi fruit is an important quality attribute that determines its market value and consumer acceptance. Plant growth regulators (PGR) such as abscisic acid (ABA) and ethephon are known to play important roles in peel colour development during maturation and ripening of non-climacteric fruits (e.g. grape and litchi). Our aim was to investigate the effects of preharvest application of ABA, ethephon and their combination on pericarp colour and fruit quality of litchi (cv. Calcuttia) and also to assess the potential effects on postharvest performance of fruit. Exogenous application of ABA (150 or 300 mg L⁻¹) at the colour-break stage significantly increased the concentration of total anthocyanins and cyanidin-3-O-rutinoside, the major anthocyanin contributing ∼71–96% of the total anthocyanins, in litchi pericarp compared to ethephon (500 μL L⁻¹). Among different anthocyanins quantified, the relative contribution of cyanidin-3,5-diglucoside to the total anthocyanins was significantly higher in all PGR-treated fruit compared to the control, but the concentration of cyanidin-3-O-glucoside was specifically enhanced by ABA. No significant effect on the concentrations of epicatechin, and quercetin-3-O-rutinoside was observed in response to PGR treatments. Ethephon (500 μL L⁻¹) treatment did not significantly increase the anthocyanin levels in pericarp, but it caused more degradation of chlorophyll pigments than control. Aril quality with regard to firmness, soluble solids and acidity was not significantly affected by PGR treatments, except that ethephon-treated fruit showed significant softening and lower acidity. Postharvest changes in fruit quality attributes including pericarp browning during cold storage at 5 °C for 14 d were mainly related to the storage duration effect, rather than PGR treatment. In conclusion, ABA treatment (150 or 300 mg L⁻¹) at the colour-break stage enhanced anthocyanins accumulation in litchi pericarp without adversely affecting postharvest quality and storage stability for 14 d.     

Induction of H2O2-metabolizing enzymes and total protein synthesis by antagonistic yeast and salicylic acid in harvested sweet cherry fruit

The immersion of sweet cherry fruit in Pichia membranefaciens at a concentration of 5 × 10⁷ cells ml⁻¹ or in salicyclic acid (SA) at 0.5 mM for 10 min reduced the incidence of decay and lesion size caused by Penicillium expansum. Without pathogen inoculation, peroxidase (POD) activity was enhanced in yeast-treated fruit, but activities of catalase (CAT) and superoxide dismutase (SOD) showed a decrease in the same fruit. SA-treatment significantly inhibited CAT activity, but stimulated SOD and POD activities. After inoculation with P. expansum, CAT activity decreased and SOD activity increased in both yeast- and SA-treated fruit. No obvious difference was found in POD activity between treatments and water control. Treatments with yeast and SA changed the expression of POD isozymes. In addition, yeast and SA treatment increased total protein content of sweet cherry and up-regulated 33 and 47 kDa protein bands shown by SDS-PAGE. These results indicated that yeast- and SA-treatments induced synthesis of anti-oxidant enzymes and specific proteins, which may play a role in the resistance against postharvest blue mold.     

Nitric oxide participates in the regulation of LeCBF1 gene expression and improves cold tolerance in harvested tomato fruit

Nitric oxide (NO) is an important signal molecule involved in numerous plant responses to biotic and abiotic stress. C-repeat/dehydration-responsive element (CRT/DRE)-binding factors (CBFs) play a prominent role in cold response regulation. To investigate the relationship between NO and the CBF pathway during cold stress, tomato (Solanum lycopersicum cv. Lichun) fruit were treated with the NO donor (sodium nitroprusside, SNP) and nitric oxide synthase (NOS) inhibitor (N (omega)-nitro-l-arginine, l-NNA) before storage at 2 °C. Treatment with 0.02 mM SNP decreased the chilling injury (CI) index, whereas l-NNA treatment increased the appearance of chilling symptoms. NO content in fruit following SNP treatment was higher, while malondialdehyde (MDA) content and ion leakage were lower than that in water- and l-NNA-treated fruit. The relative expression of LeCBF1, measured by q-RTPCR, in SNP-treated fruit was higher than that in l-NNA-treated and control fruit after cold storage for 0.5 and 4 h. These results suggest that SNP treatment protects tomatoes from cold injury by inducing NO accumulation and expression of LeCBF1. NOS activity may play a role in NO accumulation associated with cold tolerance.     

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.     

Metabolite content of harvested Micro-Tom tomato (Solanum lycopersicum L.) fruit is altered by chilling and protective heat-shock treatments as shown by GC-MS metabolic profiling

The primary aim of this study was to identify metabolites associated with chilling tolerance that was engendered by a heat-shock treatment of tomato fruit pericarp (Solanum lycopersicum L. cv. Micro-Tom). Harvested mature-green fruit were immersed in 20 or 40 °C water for 7 min (‘Heat-Shock’) and then stored at 2.5 °C for 0 or 14 d (‘Chilled’). A reduction in chilling injury symptoms (i.e., slow or abnormal ripening, increased ion leakage, and increased respiration following chilling) was used to select this heat-shock treatment as optimal. Using GC-MS (Gas Chromatography-Mass Spectrometry) metabolite profiling, 363 analytes were detected in fruit pericarp of which 65 are identified metabolites. Principal Component Analysis of these data led to distinct groups among the samples based on their treatments; ‘Chilled’ and ‘Chilled + Heat-Shocked’ fruit were markedly different from each other, while the ‘Non-Chilled Control’ and ‘Heat-Shocked’ fruit were similar and grouped closer to the ‘Chilled + Heat-Shocked’ fruit. These results indicate that the heat treatment provided protection from chilling in part by altering levels of fruit metabolites. The levels of arabinose, fructose-6-phosphate, valine and shikimic acid appear to be associated with this heat-shock induced chilling tolerance since their levels were altered in the ‘Chilled’ samples (p < 0.05), relative to the control and the heat-shocked protected fruit. We also describe the metabolites we identified that could be further studied as being indicative of incipient chilling injury in mature-green tomato fruit.     

白头翁素对PRV、E.coli混合感染性腹泻肠道超微结构的影响

白头翁素是白头翁的主要成分,对腹泻具有显著的防治效果。本试验利用猪轮状病毒和大肠杆菌混合感染建立腹泻模型,采用电镜技术动态观察白头翁素对腹泻小鼠肠道显微结构变化的影响,揭示白头翁素防治腹泻的机制。结果显示,感染小鼠肠绒毛损伤严重,表现萎缩脱水、空泡化和绒毛顶端膨大基底缩小的特征。白头翁素防治组小鼠肠道损伤明显减轻,肠道粘膜恢复时间显著缩短。结果表明,白头翁素对轮状病毒和大肠杆菌混合感染性腹泻具有显著防治功效,机制可能与其减轻肠道粘膜损伤并加速粘膜修复有关。     

套袋对白水县苹果质量及效益的影响

白水县是陕西苹果的最佳优生区,套袋苹果已占苹果生产总量的65.54%,是无公害苹果生产的关键技术之一,研究套袋技术对苹果生产具有重要的指导意义。项目对白水县苹果套袋情况进行了系统的调查,并就生产中三种果袋对苹果外观质量、内在质量、果实黑点病发生情况、效益等进行了研究。研究结果表明：目前生产中应用较多的仍然是双层双色纸袋和单层双色劣质纸袋,果实套袋能显著提高果实光洁度、着色度、果实外观鲜艳,降低VC含量,增加黑点病发病率,其中套双层三色优质纸袋苹果黑点病发病率轻,为5.2%,而套单层双色劣质纸袋重,高达47.7%,套袋能显著提高苹果生产的经济效益     

氨基酸胁迫对小麦种子幼苗生长和体内游离氨基酸水平的影响

摘 要：用赖氨酸、苏氨酸两种氨基酸单因子胁迫和两因子协同胁迫不同蛋白质含量小麦品种种子的发芽幼苗,发现5 mmol/l浓度可严重抑制根系生长,但对叶生长抑制较轻;两种氨基酸具有协同抑制作用。相比较,高蛋白含量基因型品种比低蛋白含量基因型品种可忍耐较高浓度氨基酸胁迫。HPLC方法测定胁迫植株体内游离氨基酸含量,发现胁迫氨基酸有比对照高3～10倍积累,同族氨基酸有比对照高2～3倍积累,相关氨基酸也有1～2倍积累。     

Effect of ethylene degreening on the development of postharvest penicillium molds and fruit quality of early season citrus fruit

The effect of commercial degreening with ethylene gas on fruit susceptibility and quality and development of postharvest green (GM) and blue (BM) molds on early season citrus fruit was investigated. Each cultivar was harvested with different peel color indexes (CI). Fruit were exposed for 3 d to 2 μL L⁻¹ ethylene at 21 °C and 95–100% RH before or after artificial inoculation with Penicillium digitatum or Penicillium italicum. Control fruit were kept at the same environmental conditions without ethylene. Fruit were stored at either 20 °C for 7 d or 5 °C for 14 d and disease incidence (%) and severity (lesion diameter) were assessed. No significant effect of commercial degreening was observed on fruit susceptibility to both GM and BM on citrus cultivars inoculated after degreening. Likewise, no significant effect was observed on disease incidence on citrus cultivars inoculated before degreening and stored at either 20 °C for 7 d or 5 °C for 14 d. In contrast, in cultivars like ‘Clemenules’ mandarins and ‘Navelina’ oranges, degreening significantly increased the severity on fruit with higher initial CI (−3.6 and 1.7, respectively). GM and BM severity on degreened and control ‘Clemenules’ mandarins incubated at 20 °C for 7 d was 146 and 118 mm and 56 and 46 mm, respectively. In general, commercial degreening did not significantly affect external and internal quality attributes of citrus cultivars. Commercial degreening after inoculation of less green (more mature) fruit showed a trend to increase mold severity, presumably through an aging effect (acceleration of peel senescence).     

花生品种主要脂肪酸含量在不同生态区的稳定性

花生是主要的油料作物,脂肪酸组成受环境等的影响而不稳定。本研究选取60份黄淮及长江流域产区主推的花生品种,连续2年在湖北武汉、河北石家庄、河南濮阳和河南周口4个环境下种植,利用GB/T5510-2011法检测种子脂肪酸含量。结果表明,高油酸花生品种油酸含量比普通油酸品种稳定,普通油酸品种棕榈酸和亚油酸含量比高油酸品种稳定;武汉种植环境有利于花生油酸含量的提高,2年60份品种的平均油酸含量均最高,分别为52.93%和52.64%;高油酸花生品种除油酸含量显著提高外,花生烯酸含量也提高了54.1%;而棕榈酸和亚油酸含量分别降低了45.20%和90.44%。结合前期SSR研究结果,本研究涉及的6份高油酸品种属于不同的类群(G1、G2c和G2e),其遗传背景差异较大。本研究结果为花生品种的合理布局和进一步的遗传改良提供了理论依据。     

Effect of fruit load on oil yield components and dynamics of fruit growth and oil accumulation in olive (Olea europaea L.)

Olive oil yield and its components (fruit number, average fruit weight and fruit oil concentration) depend on crop load and source–sink ratios as affected by environmental conditions, management and the alternate bearing typical of the species. The aims of this work were to: (i) establish quantitative relationships between oil yield and its components as affected by fruit load in a high-yielding production system, (ii) analyse the dynamics of fruit weight and fruit oil concentration in terms of rates and durations, and (iii) explore the relationships between the dynamics of oil and water in fruit. In a fully irrigated olive orchard in Mendoza (32° S), Argentina, cv. Arbequina trees with similar crown volume and three fruit loads (3-fold range) were monitored during two seasons. Oil yield was positively associated with both fruit number and fruit fresh weight, but not with fruit oil concentration. Across seasons and fruit loads, fruit yield increased linearly with fruit number at ～1.5 kg per thousand fruit and reached a maximum ～60 kg tree^?1 (or 25 t ha^?1) at a fruit load of 32,700 fruit tree^?1. The fruit filling rate was affected by fruit load, while the duration of fruit growth and the dynamics of oil and water concentration were unaffected by fruit load. Fruit water concentration reached a minimum at the onset of Stage III of fruit growth, which was marked by a rapid increase in oil concentration. Fruit fresh weight and oil weight increased with source–sink ratio from ～0.5 up to a threshold ～2 m³ crown per thousand fruit. In contrast, a 8-fold range of source–sink ratio did not affect fruit oil concentration.     

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.