采后纳米氧化锌对苹果黑斑病和青霉病的控制

通过离体(in vitro)和体内(in vivo)实验,研究了纳米氧化锌处理对苹果采后主要致腐病菌Alternaria alternata和Penicillium expansum生长的抑制及对病害的控制效果。结果表明:纳米氧化锌对两种病菌的菌丝生长均具有明显的抑制作用,且抑制效果随浓度的升高而增加,其中20%的纳米氧化锌对A.alternata和P.expansum的抑菌率分别达到86.85%和49.60%,对前者抑制效果显著优于后者。20%纳米氧化锌处理对A.alternata孢子萌发的抑制较对照下降了87.37%,而15%纳米氧化锌处理对P.expansum孢子萌发的抑制较对照下降了94.56%。同时纳米氧化锌也显著降低了损伤接种A.alternata和P.expansum苹果病斑直径的扩展,其中以5%纳米氧化锌处理效果最好,分别与对照相比降低了76.24%和65.32%,更高浓度处理并没有增强抑制效果。由此表明,纳米氧化锌可通过直接抑菌作用来减轻苹果黑斑病和青霉病的发生。     

采后纳米氧化锌对苹果黑斑病和青霉病的控制

通过离体(in vitro)和体内(in vivo)实验,研究了纳米氧化锌处理对苹果采后主要致腐病菌Alternaria alternata和Penicillium expansum生长的抑制及对病害的控制效果。结果表明:纳米氧化锌对两种病菌的菌丝生长均具有明显的抑制作用,且抑制效果随浓度的升高而增加,其中20%的纳米氧化锌对A.alternata和P.expansum的抑菌率分别达到86.85%和49.60%,对前者抑制效果显著优于后者。20%纳米氧化锌处理对A.alternata孢子萌发的抑制较对照下降了87.37%,而15%纳米氧化锌处理对P.expansum孢子萌发的抑制较对照下降了94.56%。同时纳米氧化锌也显著降低了损伤接种A.alternata和P.expansum苹果病斑直径的扩展,其中以5%纳米氧化锌处理效果最好,分别与对照相比降低了76.24%和65.32%,更高浓度处理并没有增强抑制效果。由此表明,纳米氧化锌可通过直接抑菌作用来减轻苹果黑斑病和青霉病的发生。      

采后热处理对红富士苹果青霉病和灰霉病的控制

热空气处理能有效抑制灰葡萄孢(Botrytiscinerea)和扩展青霉(Penicilliumexpansum)的毒性。灰葡萄孢比扩展青霉的热敏感度高,Bcinerea孢子38℃热处理48h即能完全抑制孢子萌发。热处理72h的Bcinerea平板均无菌丝生长。Pexpansum的孢子活性和菌丝生长随热处理时间的延长而明显减缓。热处理后的霉菌孢子在苹果果实内生长缓慢,Bcinerea孢子在热处理72h后在苹果中的生长完全受抑制,腐烂发生率为零。Pexpansum热处理72h后才能显著抑制苹果的腐烂发生。苹果接种霉菌后再进行热处理(38℃,96h),无论是0℃还是20℃下放置,均未发现腐烂,大大减少贮期灰霉病、青霉病的发生。研究还发现,经过2个月冷藏后,与对照组相比,热处理过的红富士苹果果皮色泽更黄,糖酸比上升,呼吸强度较低,硬度保持较好,说明热处理能够正面影响苹果的贮藏品质。     

热处理结合β-氨基丁酸对苹果采后青霉病的控制

研究热处理、β-氨基丁酸(BABA)及其复合处理对苹果青霉病控制效果的影响,并对其复合处理条件进行优化。研究表明45℃热处理和BABA单独处理均能降低处理后损伤接种Penicillium expansum的苹果病斑直径的扩展,45℃热处理8min与50mmol/L BABA处理5min其病斑直径仅为对照的82.86%、80.76%。初步复合处理实验表明热与BABA复合处理先后顺序对青霉病控制效果无显著性差异,处理间隔时间对控制效果有一定的影响。对复合处理条件进行正交试验优化,结果表明热处理时间对试验结果的影响最大,最优处理条件为45℃热处理6min、间隔10min后以50mmol/L BABA浸泡处理。验证实验表明,热与BABA复合处理能有效缩短热处理时间并显著地提高对苹果采后青霉病的控制效果。     

外源一氧化氮对苹果采后黑斑病的控制

在离体条件下研究了NO供体硝普钠(sodium nitroprusside,SNP)对苹果黑斑病菌互隔交链孢(Alternaria alternata)生长、菌落形态及其超微结构的影响,并在体内条件下研究了其对苹果黑斑病的治愈作用。结果表明SNP处理能显著的抑制A.alternata的孢子萌发和菌丝生长,存在浓度依赖效应,当浓度为1 g/100 m L SNP,与对照相比,其对菌丝生长和孢子萌发的抑制率分别达到70%和75.9%;扫描电镜和透射电镜观察发现SNP处理的A.alternata菌丝表面粗糙,粗细不均匀,部分出现塌陷;孢子细胞受到不同程度的破坏,细胞膜发生破裂。同时发现外源SNP处理对损伤接种的苹果黑斑病具有治愈作用,其中0.5 g/100 m L SNP处理效果最佳。可见外源NO作为代替化学合成药物的防腐剂在采后病害控制中具有潜在的应用前景。      

采后柠檬酸处理对苹果青霉病的控制及其贮藏品质的影响

以苹果为原料,研究不同质量分数柠檬酸常温浸泡处理对损伤接种扩展青霉（Penicillium expansum）果实病斑扩展的抑制效果及贮藏品质的影响。结果表明：离体条件下柠檬酸能够抑制P. expansum的孢子萌发,其中以1%质量分数效果最佳,1%柠檬酸处理显著降低了损伤接种苹果果实P. expansum病斑直径;柠檬酸处理显著提高了果实过氧化物酶、过氧化氢酶和抗坏血酸过氧化物酶活性。此外,柠檬酸处理还有效延缓了果实质量损失率的升高,抑制果实硬度、抗坏血酸含量、可滴定酸和可溶性固形物质量分数的下降,且推迟了果实呼吸高峰的出现。     

碳酸盐和碳酸氢盐对鸭梨采后黑斑病和青霉病的控制研究

对不同浓度碳酸盐和碳酸氢盐处理对鸭梨采后黑斑病和青霉病的影响进行了研究。结果表明,离体实验中,碳酸盐和碳酸氢盐对链格孢和青霉菌的菌落生长均具有很强的抑制作用,其中2%碳酸钠、碳酸氢钠和碳酸氢钾对链格孢和青霉菌的抑菌率分别达到89%和98.1%,84.9%和96%,81.6%和95.1%。碳酸盐和碳酸氢盐对Penicilliumexpansum的抑制效果均优于Alternariaalternata。在活体实验中,室温下碳酸盐和碳酸氢盐处理对鸭梨人工损伤种的黑斑病菌和青霉病菌有抑制作用,但差异不显著。     

钙结合双酵母对苹果采后青霉病诱导抗性机制

水果含有丰富的营养物质,但其在采后贮藏或运输期易发生侵染性病害而导致果肉腐烂和品质下降,造成严重的经济损失。为筛选抑制效果最佳的CaCl2 浓度并探究其与双酵母最佳结合浓度下对苹果果实的抗性诱导机制,该文通过体外接种实验确定添加CaCl2 后的最佳培养时间为24 h;体内实验表明不同浓度CaCl2 诱导双酵母对苹果青霉病均有抑制效果,其中2.0% CaCl2 抑制效果最佳;通过在苹果伤口及表面处的生长动态发现2.0% CaCl2 可促进双酵母迅速定殖;2.0% CaCl2 诱导后可以显著提高苹果中苯丙烷代谢相关酶、活性氧代谢相关酶活性和物质含量。相较对照和使用双酵母复配,CaCl2 处理能够增强拮抗酵母的生防效力,一方面可以促进拮抗酵母的生长和定殖,另一方面可以降低果实的发病率并增强果实的抗病性。     

采后茉莉酸甲酯处理对富士苹果青霉病和贮藏品质的影响

以富士苹果为材料,研究采后茉莉酸甲酯（methyl jasmonate,MeJA）处理对果实损伤接种扩展青霉的抑制效果及对过氧化氢（H2O2）含量、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性及果实贮藏品质的影响。结果表明,100 μmol/L MeJA处理10 min对苹果果实青霉病的抑制效果最好,MeJA处理提高了果实SOD活性,促进了果实体内H2O2的积累,抑制了CAT的活性。此外,外源MeJA处理明显提高了果实抗坏血酸含量,降低了贮藏期间果实的质量损失率,对果肉硬度、可溶性固形物和可滴定酸含量无显著影响。由此推测,采后经MeJA处理的苹果果实抗病性提高和果实品质保持与抗氧化能力的提高有关。     

枯草芽孢杆菌QDH-1-1对采后苹果青霉病的抑制效果

目的研究一种从番茄叶面分离获得的拮抗菌--枯草芽孢杆菌(Bacillus subtilis)QDH-1-1对苹果采后青霉病的防治效果.方法通过拮抗菌的不同处理、使用浓度及与钙配合等方法研究了枯草芽孢杆菌对青霉病的抑制作用.结果表明拮抗菌使用浓度明显地影响苹果中病斑发生和病斑扩展,且使用浓度越大,其抑病效果越好.当拮抗菌的使用浓度达到109CFU/mL时,可完全抑制接种在苹果上的青霉菌(Penicillium expansum,104CFU/mL)的侵染.用108～109CFU/mL的拮抗菌与2%CaCl2配合对苹果采后青霉病的抑制效果明显地好于单独使用相同剂量的拮抗菌或2%CaCl2.拮抗菌的不同处理对病原菌孢子萌发的抑制效果与体内试验结果一致.结论枯草芽孢杆菌QDH-1-1主要通过营养和空间竞争作用抑制病原菌生长.     

Effects of apple and pear varieties and pH on patulin accumulation by Penicillium expansum

BACKGROUND: Accumulation of patulin in apples and pears and subsequently in their by‐products is caused mostly by Penicillium expansum which causes blue mould. Fruit pH and other parameters are sometimes characteristic of a certain variety and thus the use of particular varieties might affect patulin content in the final products. The aim of this study was to evaluate the influence of fruit variety and pH on patulin accumulation. Patulin accumulation in both apple and pear juices at different pH and also in different apple varieties (Golden, Gala and Fuji) and pear varieties (Blanquilla and Conference) was assessed. RESULTS: The pH of juices significantly influenced patulin accumulation, especially in apple juice in which the highest amounts of patulin were detected at pH 3.5. In fruits, the pH values of the substrate were determinant only under cold storage. Thus, Golden apples, which presented a lower pH, accumulated more patulin at 1 °C. However, this trend was not observed at other temperatures in which varieties with higher amounts of organic acids (Golden and Fuji apples) accumulated most patulin. In the pear varieties, significant differences in pH did not lead to significant differences in patulin accumulation. CONCLUSION: Although pH influences patulin accumulation, other factors such as organic acid content may play an important role. Concerning the apple and pear varieties we studied, it seems that rather than variety, other parameters like pH or acidic content may be more important. These parameters vary significantly depending on the degree of ripeness of the fruit. Gala apple, which is used in Spanish juice production, was the only variety that accumulated dramatically higher amounts of patulin. Copyright © 2008 Society of Chemical Industry     

l-glutamate inhibits blue mould caused by Penicillium expansum in apple fruits by altering the primary nitrogen and carbon metabolisms

Although several studies have shown the ability of l -glutamate (glutamate) to mitigate the stress imposed by pathogens, the underlying mechanism is still in its infancy. To gain further knowledge, this study focussed on the effect of glutamate on primary nitrogen and carbon metabolisms during apple-Penicillium expansum interaction. The obtained result showed that glutamate could effectively restrict blue mould rot development in apples, but had no direct impact on fungal growth in vitro. The application of glutamate increased the level of nitrogen in apples, resulting in a disrupted balance of carbon and nitrogen. Consistently, the key enzymes glutamine synthetase (GS) and glutamate synthase (GOGAT) involved in the GS/GOGAT cycle, and the deaminating activity of glutamate dehydrogenase (GDH), forming 2-oxoglutarate and ammonium from glutamate, were promptly stimulated by glutamate. Interestingly, glutamate led to considerable consumption of the tricarboxylic acid (TCA) cycle intermediates, such as isocitric acid and citric acid, accompanied by the enhancement of malate dehydrogenase and succinate dehydrogenase activities. Collectively, exogenous application of glutamate might confer blue mould resistance in apples, at least in part, by redirecting host’s primary nitrogen and carbon metabolisms, such as the activation of the GS/GOGAT cycle, deaminating activity of GDH and the TCA cycle.     

Efficacy of preharvest and postharvest Candida sake biocontrol treatments to prevent blue mould on apples during cold storage

This study compared the biocontrol efficiency of preharvest and postharvest applied yeast cells of Candida sake to apples (cv. Golden Delicious) wounded before and after harvest and inoculated with Penicillium expansum prior to cold storage conditions in two seasons, 1994/95 and 1995/96. The establishment of populations of C. sake during this period also was determined. In both years, postharvest treatment with the antagonist resulted in significant (P<0.05) and effective control of Penicillium rot whether pre- or postharvest wounds were made. Maximum disease control achieved, in terms of incidence and severity, was greater than 80% reduction in lesion diameter and 50% reduction in the incidence of lesions. However, preharvest application of the antagonistic yeast at a concentration of 3·10⁶ CFU/ml was less effective against Penicillium rot than postharvest treatment. No advantages in biocontrol were observed when apples were treated with the yeast antagonist both pre- and postharvest. Candida sake population levels during cold storage of apples receiving only preharvest application of the antagonist decreased prior and more rapidly than levels in apples receiving a postharvest application. High populations of C. sake were present in postharvest-treated apples, even after 90 days in cold storage.     

汉逊德巴利酵母对采后柑橘青霉病的防治及贮藏品质的影响

利用汉逊德巴利酵母不同浓度梯度的处理液对指状青霉体外和柑橘上进行生物防治试验。体外实验表明,108CFU/mL酵母溶液牛津杯产生的抑菌圈为20.6 mm,在PDB培养基中青霉孢子24 h后的萌发率和芽管长度分别为5.2%,11.4μm。柑橘体上实验表明,108CFU/mL酵母溶液处理组8 d后的病斑直径和发病率分别为3.6 mm和7.4%,病变指数仅为7.8%,防治效率达到了92.3%。拮抗酵母可以防止柑橘总糖和Vc的损失,防止柑橘霉变引起的总酸增长。25℃左右的条件下,108CFU/mL的酵母溶液能够较好地抑制柑橘青霉病的发生也保证柑橘的贮藏品质。     

Patulin in apple juices: Incidence and likely intake in an Indian population

The quality and safety of Ayurvedic formulations has become a serious issue, as this Indian system of medicine is used by 80% of the Indian population. Hence, the present study was performed to evaluate heavy metals contents by flame atomic absorbance spectroscopy (AAS) measurements and confirmation by inductive coupled plasma–mass spectroscopy (ICP-MS). A total of 78 formulations (56 herbal, 19 herbometallic and 3 metallic) were sampled. In herbal formulations, lead in 19.6% (11/56), cadmium in 21.4% (12/56), mercury and arsenic in 5.3% (3/56) were above the limit. Lead in 52.6% (10/19) of samples, cadmium in 26.3% (5/19) and mercury and arsenic contained in one herbometallic sample was above the limit. Heavy metals in all metal formulations were above the WHO limit. Significant batch variation was observed. The analytical results of flame AAS and ICP-MS did not differ significantly in the range of measurements in this study, which proves that both methods are satisfactory for estimation of heavy metals in these type of samples.     

梨火疫病菌活菌快速定量检测方法的建立

目的：为建立一种叠氮溴化丙锭（Propidium Monoazide,PMA）与实时定量聚合酶链式反应（Quantitative real-time Polymerase Chain Reaction,qPCR）联用的快速检测扩展青霉活菌方法。方法：通过优化PMA处理浓度、黑暗孵育及曝光时间,筛选扩展青霉特异性引物,结合qPCR技术,建立一种基于PMA-qPCR联用快速检测扩展青霉活菌的方法,构建定量标准曲线,应用于人工污染的苹果样品中活菌的检测,与平板菌落计数比较评估该方法的可靠性。结果：PMA处理浓度10 µg/mL、黑暗孵育5 min、曝光10 min为最佳PMA处理条件。4种引物中Pexp-patF对扩展青霉具有极强的特异性,可作为引物用于PMA-qPCR检测。构建的定量标准曲线的R²=0.9948,最低检测限为10^2.6 CFU/mL,方法检测结果与平板菌落计数无明显差异,并发现在苹果的未腐烂部分中可检测出扩展青霉活菌。结论：研究建立的PMA-qPCR技术可应用于苹果中扩展青霉活菌的检测,为扩展青霉精准防控提供一定技术支撑。