Evaluation of commercial essential oil samples on the growth of postharvest pathogen Monilinia fructicola (G. Winter) Honey

Aim: To assess the effect of several commercial essential oils samples Australian lemon myrtle (Backhousia citriodora), cinnamon bark (Cinnamomum zeylanicum), oregano (Origanum vulgare), thyme oil (Thymus vulgaris), clove bud (Eugenia caryophyllata), valerian (Valeriana officinalis) and Australian tea tree oil (Melaleuca alternifolia) on mycelium growth and spore germination of Monilinia fructicola. The effectiveness of lemon myrtle essential oil as a fumigant for the control of brown rot in nectarines was evaluated. Methods and Results: Monilinia fructicola exhibited a different level of sensitivity to each tested essential oil with results suggesting that the essential oils provide excellent control of the pathogen with respect to mycelium growth and spore germination at very low concentrations, whereas for others higher concentrations are needed to reduce significant fungal growth. In vivo application of lemon myrtle essential oil effectively reduced the incidence of M. fructicola on noninoculated fruit. Fumigation of nectarines following inoculation did not reduce the incidence of brown rot in comparison with the inoculated control treatment. No evidence of phytotoxicity on the fruit was recorded. Conclusions: Lemon myrtle essential oil exhibited the strongest antifungal activity against M. fructicola, in vitro and to a lesser extent, under in vivo conditions. Significance and Impact of the Study: The results demonstrate that lemon myrtle essential oil, in particular, has potential as an antifungal agent to control M. fructicola.     

钙处理对枇杷果实采后若干生理指标影响初报

不同浓度(0.2%、0.5%、0.8%)CaCl₂溶液处理采后的枇杷果实,能抑制果实呼吸,减少乙烯释放,降低细胞膜透性。     

Effects of ozone treatment on the quality of kiwifruit during postharvest storage affected by Botrytis cinerea and Penicillium expansum

The objective was to reveal the effects of ozone treatment on quality maintenance and resistance to Botrytis cinerea and Penicillium expansum in kiwifruit during postharvest storage. Kiwifruits were treated with 79.44 ppm gaseous ozone for 1 hr once a day for 7 day at 0°C to determine the effects of ozone treatment on the quality and disease incidence caused by B. cinerea and P. expansum in vivo and the growth of B. cinerea and P. expansum in vitro. Ozone treatment significantly reduced the disease incidence of kiwifruit and inhibited the mycelial development and spore germination of B. cinerea and P. expansum. High levels of fruit firmness and titratable acidity were maintained in the ozone‐treated kiwifruit, and the activities of the defence‐related enzymes were remarkably enhanced. Therefore, ozone treatment may be an effective method to maintain the quality of kiwifruit and control its decay during postharvest storage.     

In vitro activity of glucosinolate-derived isothiocyanates against postharvest fruit pathogens*

The authors assayed the ability of some reaction products, essentially isothiocyanates, derived from the myrosinase-catalysed hydrolysis (neutral pH) of six natural glucosinolates to inhibit germination and mycelial growth of Botrytis cinerea, Rhizopus stolonifer, Monilinia laxa, Mucor piriformis and Penicillium expansum, the leading postharvest fungal pathogens of fruit and vegetable crops. All of the tested products showed antifungal activity, although they proved less effective against mycelial growth than in germination control. The isothiocyanates produced by enzymatic hydrolysis of glucoraphenin, sinalbin and sinigrin were particularly effective because they completely inhibited conidic germination of all five pathogens considered. The sinigrin-derived isothiocyanate exhibited a wide pathogen-control spectrum, either inhibiting conidia germination altogether or delaying by 3–6 days the onset of mycelial growth compared to the control.     

Acetic Acid, Ethanol and Steam Effects on the Growth of Botrytis cinerea in vitro and Combination of Steam and Modified Atmosphere Packaging to Control Decay in Kiwifruit

The effects of acetic acid fumigation, ethanol fumigation, and steam heat treatment on growth of Botrytis cinerea in vitro were investigated. The effect of steam heat treatments in combination with modified atmosphere packaging (MAP) on Botrytis decay development on 'Hayward' kiwifruit was also studied. The fungus was grown in Petri dishes on potato dextrose agar. Ethanol fumigation with 100  μ l/l for 3 or 6 min, or 200  μ l/l for 6 min enhanced the growth of B. cinerea . The effect of acetic acid on growth of B. cinerea was time and dosage-dependent. Fumigation with 1  μ l/l for 6 min, 2  μ l/l for 3 min, and 4  μ l/l for 3 min promoted radial growth of the fungus when compared to the growth of the untreated control. Fumigation with 2  μ l/l for 6 min delayed the growth of the fungus for the first 6 days, while fumigation with 6  μ l/l for 3 min delayed the growth of the fungus after the sixth day. Fumigation with 4 or 6  μ l/l acetic acid for 6 min, and 8  μ l/l acetic acid for 3 or 6 min resulted in complete inhibition of fungal growth. Steam heat treatment at 45°C for 6 min, and at 48, 51, and 54°C for 3 or 6 min completely inhibited fungal growth in vitro . Furthermore, steam treatments at 47, 50, and 53°C for 3 or 6 min completely inhibited decay at the stem end of kiwifruit kept at 10°C in MAP for 12 days. However, none of the steam treatments inhibited decay in wounds on the surface of the fruit kept in MAP.     

Induction of Peroxidase during Infection of Unripe Persimmon Fruit by Alternaria alternata: a Possible Quiescence Mechanism

Limited black spot symptoms (Quiescent infections) develop on persimmon fruits as Alternaria alternata hyphae penetrate the pericarp of green‐immature fruit. Inoculation of persimmon with A. alternata or treatment with a commercial preparation of purified cellulase induced similar black symptoms and higher peroxidase activity in green‐immature fruits but not in orange‐mature persimmon fruits. Both treatments induced the development of new peroxidase isoforms only in immature fruits – however, no effect was observed on polyphenoloxidase activity. A. alternata was transformed with a construct expressing green fluorescent protein (GFP). Histological analysis of hyphal development using GFP‐transformed fungi indicated that symptoms are always found ahead of the leading edge of the hyphae. We suggest that peroxidase increase, induced by the directly penetrating A. alternata, might be involved in the induction of quiescence infection by the pathogen in immature fruits.     

Postharvest biological control of Penicillium digitatum decay on citrus fruit by Bacillus pumilus

A new antagonist/pathogen combination is reported, with Bacillus pumilus showing strong antagonistic activity against Penicillium digitatum. B. pumilus (1.6 × 10¹⁰ to 1.6 × 10¹²*cfu ml^-1) gave significant control of P. digitatum infection in Valencia orange, which was as effective as imazalil (500 μg ml^-1) and was significantly better than benomyl treatment (500 μg ml^-1). When lower concentrations of B. pumilus (1.9 × 10⁷ to 1.9 × 10⁹ cfu ml^-1) were tested on Washington Navel orange and Lisbon lemon fruit, the antagonist caused significant control of P. digitatum infection at two inoculum levels (6.5 × 10⁴ and 6.5 × 10⁵ spores ml^-5). Concentrations of both the pathogen and the antagonist affected the biocontrol effect.     

壳聚糖在香蕉果实贮藏保鲜上的应用效果

以巴西香蕉果实为材料,研究了不同浓度（0、0．5％、1．0％、2．0％）的壳聚糖溶液对香蕉果实贮藏保鲜的影响。结果表明：壳聚糖处理可明显延缓香蕉果实的软化进程和病情指数的升高;同时维持了果实较低的细胞膜透性、多酚氧化酶（PPO）活性和较高的苯丙氨酸解氨酶（PAL）、β-1,3-葡聚糖酶（GUN）的活性。在四种处理中,以2％壳聚糖处理效果最好。表明壳聚糖对香蕉果实的贮藏保鲜效应可能与其调控病害相关酶的活性有关。     

Aureobasidium pullulans as a biocontrol agent of postharvest pathogens of apples in Uruguay

Aureobasidium pullulans was the microorganism most frequently recovered from the surface of apple fruit (cv. Red Delicious) stored in commercial cold chambers for 6 months. In the present work, 10 isolates of Aureobasidium pullulans were assayed to determine if they could control blue and grey mold disease of apple during cold storage. Although nine of 10 isolates, significantly reduced the percentage of decayed wounds when compared to the control, one of them, designated isolate ApB, showed the highest levels of protection. ApB was able to grow in a wide range of temperatures lower than 35°C, which is an important human health safety factor. ApB was resistant to thiabendazole, iprodione and imazalil, the most commonly commercially applied fungicides in postharvest treatment of apples in Uruguay. Regarding the mechanisms of action of the selected biocontrol agent, lytic enzymes did not seem to play a central role. ApB depleted iron from nutrient media, which may be an important aspect of its ability to inhibit Botrytis cinerea. Further experiments are needed, however, to determine if the depletion of iron is caused by the production of siderophores, by the immobilization of iron in an insoluble pigment, or a combination of both.     

Study of antifungal activities of seven essential oils from some Iranian medicinal plants against various postharvest phytopathogenic fungi

The aim of this study was to find the antifungal activities of seven essential oils from some Iranian medicinal plants that have maximum (100%) inhibition effect on the mycelium growth of postharvest phytopathogenic fungi. Among 20 examined species belonging to three families, only 7 species could stop the mycelium growth of phytopathogenic fungi. The selected plants include Trachyspermum ammi, Zataria multiflora Boiss., Satureia hortensis, Caryophillum aromaticus, Menthe piperita, Cuminum cyminum L. and Carum carvi, and fungi include Aspergillus flavus, Botrytis cinerea, Penicillium italicum, Penicillium expansum, Penicillium commune, Rhizopus stolonifer and Rhizopus lyococcus. The results showed that the essential oil of these plants could stop the mycelium growth at 500 ppm, but could not completely inhibit the spore germination, however reduced the spore germination to 80–90%. Among the fungi Rhizopus stolonifer and Rhizopus lyococcus are more resistant to the inhibition effects of essential oils. Among the plants, Cuminum cyminum L. and Carum carvi were slightly weaker than other plants. Also except for Cuminum cyminum L. and Carum carvi, the essential oils of other plants had fungicide effect while these two plants in most cases had fugistatic effect. The results showed that these essential oils can be used as an effective alternative control method.     

黄花菜的采后生理与保鲜技术研究进展

黄花菜(Hemerocallis citrina Baroni,daylily)在我国有几千年的种植历史,是一种具有较高经济价值的特色蔬菜。通过对国、内外在黄花菜保鲜和贮藏的研究的了解,从黄花菜的生理、保鲜两方面对黄花菜的采后生理及保鲜技术进行了综述,同时也对黄花菜的应用价值进行了介绍。     

A new improved strategy for the selection of cold-adapted antagonist yeasts to control postharvest pear diseases

Postharvest diseases cause considerable losses of harvested fruits during transportation and storage. Many yeast species have been reported as good antagonists against postharvest pear pathogens. In this work, we used a novel selection strategy that involves the isolation of yeasts from washing fluids, showing biocontrol activity against a regional Penicillium expansum strain (primary screening), originally obtained from fruit wounds after long time storage at ?1/0°C. About 26 isolates representative of the 11 yeast species identified in the 27 selected washing waters were chosen to be evaluated in a secondary screening against a regional Botrytis cinerea strain on pear wounds. Among yeasts tested, 38% showed complete control of P. expansum, but only 15% reduced the decay incidence of B. cinerea to 60–80% at ?1/0°C. These results reveal that some of the yeasts found can be biological alternatives to fungicides in the control of P. expansum and B. cinerea infections. Based on the data obtained, our strategy seems to be much more effective than the previously reported methods in obtaining successful biocontrol agents.     

Blue mould decay of stored onion bulbs caused by Penicillium polonicum,P. glabrum and P. expansum

Onion bulbs (Allium cepa L.) can be stored for up to 12 months to ensure their availability all year, but one of the limiting factors is decay caused by blue mould fungi. Postharvest development of blue mould is not only economically important, but also poses a health hazard due to mycotoxin contamination. Onion bulbs of different yellow and red cultivars with blue mould symptoms were collected from three storage facilities in Serbia. Pathogenic isolates were identified and characterized based on their molecular (partial β‐tubulin gene), morphological (micro‐ and macromorphology, and colony growth) and biochemical properties (analyses of indole metabolites via Ehrlich test). Three Penicillium species were identified: P. polonicum, P. glabrum and P. expansum. Virulence on inoculated onion bulbs varied significantly within isolates of P. glabrum, but the most virulent isolate of P. polonicum and P. glabrum did not differ, nor did they differ from an isolate of P. expansum. Variability in virulence of individual P. glabrum isolates corresponded to differences in their molecular and macromorphological characters. P. glabrum and P. expansum were identified for the first time as causal agents of onion bulb decay in Serbia. Data from this investigation provide insight into diversity of economically important and possibly toxigenic blue mould fungi which brings attention to their presence in storage facilities and therefore the necessity of the application of prevention measures.     

Biological control of Botrytis mali on apple fruit by use of Bacillus bacteria,isolated from the rhizosphere of wheat

Bacillus pumilus (B19), B. subtilis (1J), B. crerus (B16), B. subtilis (B11) and B. cereus (B17), isolated from the rhizosphere of wheat, were tested for control of gray mold of apple caused by Botrytis mali. Dual culture, cell free metabolite and volatile tests showed that all five isolates of Bacillus spp. inhibited growth of the pathogen. Inhibition varied from 13.6 to 74% in the dual culture tests; 12.3 to 87% in the cell free metabolite tests; and 11 to 53% in the volatile tests. Five isolates of Bacillus spp. reduced B. mali lesion diameter from 7.2 to 32.2 mm compared with 41.6 to 51.4 mm in controls at 4°C. At 20°C the lesion diameters were from 7 to 24.9 mm for antagonistic treatments and from 46.2 to 46.6 mm for the control treatment after 15 days.     

葡萄采后果粒脱落及保鲜贮藏

葡萄穗粳和果柄的呼吸强度与乙烯生成显著高于果粒,并呈现呼吸跃变型变化。落粒果柄中GA消失,ABA增加。降低贮藏温度、外源GA,NAA,AOA处理能抑制落粒,ABA、乙烯利则增加落粒率。剪去穗梗和果柄后果粒和果柄间不再形成离层,表明穗梗和果柄在落粒过程中起重要作用。     

Suppression of the cysteine protease,aleurain, delays floret senescence in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

An aleurain-like protein, BoCP5, is up-regulated during harvest-induced senescence in broccoli floret and leaf tissue. BoCP5 is most closely related to an Arabidopsis protein (91%, AAF43041) and has 71% identity to barley aleurain (P05167). The mRNA for this gene accumulates within 6 h after harvest in broccoli florets, and its expression is reduced in tissue that has been held in senescence-delaying treatments (e.g. water, sucrose feeding, controlled atmosphere). The gene is also expressed in leaves during aging-related and harvest-induced senescence. Analysis of protein bands that cross-react with antibodies raised to the bacterial BoCP5 fusion protein, revealed prominent immunoreactive bands at ca. 26, 28, 31, and 38 kD in floret tissue. The 31 kD band was absent in protein extracts from leaf tissue. Agrobacterium-mediated transformation was used to produce transgenic broccoli plants with down-regulated BoCP5. A reduction in the postharvest expression of BoCP5 in floret tissue was achieved for four transgenic lines in the current study. In three of these lines postharvest floret senescence (yellowing) was delayed, and florets contained significantly greater chlorophyll levels during postharvest storage at 20 °C than wild-type plants. Line 4 showed the greatest down-regulation of BoCP5, and in this line postharvest protease activity remained at pre-harvest levels, and the yield of soluble proteins extracted from florets after harvest was significantly greater than that of wild-type tissue.     

膜对采后园艺作物衰老的影响

植物衰老是由内在和外部环境因素所诱导和引起的一种主动过程 ,其中膜的劣变是这种过程早期的表现形式和基本特征。简要评述了膜系统对采后园艺作物的衰老作用。有证据表明膜系统破坏是采后园艺作物衰老的关键事件。膜脂生物化学和生物物理性质的变化、酶促和非酶促的过氧化作用导致了膜特性的改变和功能上的失调 (如离子泄漏和细胞去区域化 )。这样 ,反过来又进一步引起细胞代谢异常 ,并加速衰老进程。目前 ,膜系统对采后园艺作物衰老的作用过程正逐步得到阐明     

壳聚糖涂膜对机械伤苹果抗性生理特征的影响

为了提高苹果采后抗机械损伤能力,减少贮藏损失,以红富士苹果为材料,通过人工模拟机械伤试验,研究壳聚糖涂膜对损伤红富士苹果常温贮藏条件下果肉褐变、相关酶活性及抗性相关物质的影响,探索壳聚糖涂膜在果蔬防腐保鲜上的应用。结果显示:壳聚糖涂膜处理科显著减少红富士苹果果实机械伤口的扩张,提高机械伤果实的总酚含量,降低PPO活性,从而有效抑制机械伤苹果贮藏期间的果肉褐变的发生。同时,壳聚糖涂膜处理可提高机械伤苹果的POD和PAL活性,延缓酚类物质含量的下降,促进体内木质素的合成。研究表明,壳聚糖涂膜处理能够有效防止机械伤苹果贮藏期间的酶促褐变,减少果肉组织中有害物质的积累,促进愈伤组织的形成,从而增强了机械伤苹果的抗性,有效延缓了果实衰老。     

一氧化氮(NO)对采后青椒某些生理生化特性与品质的影响

不同浓度(0.1、0.5、1.0μmol·L-1)NO气体处理青椒果实的结果表明:0.5和1.0μmol·L.NO显著地抑制青椒果实的呼吸速率,延缓维生素C(VC)降解,0.5 μmol·L-1NO显著抑制多酚氧化酶(PPO)活性.各处理对果实中叶绿素和丙二醛(MDA)含量与未理的之间无显著差异.