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1.
    
In 2013, an outbreak of Rhizopus rot caused by Rhizopus oryzae occurred in cucumber grafted onto pumpkin rootstock sampled from seedling farms in Changnyeong, South Korea. A water‐soaked appearance of the affected tissue was the first symptom of this soft fungal rot in the seedling stems of grafted cucumber. Lesions at the graft sites softened and rapidly, rotted, and turned brown or dark brown. Measurements and taxonomic characteristics were most similar to R. oryzae. DNA sequencing and phylogenetic analysis of the internal transcribed spacer rRNA gene region confirmed that the isolates were indeed R. oryzae. Koch's postulates were supported by pathogenicity tests conducted on healthy plants. Based on mycological characteristics, pathogenicity test, and molecular analysis, the causal fungus was identified as R. oryzae Went & Prinsen Geerligs. To our knowledge, this is the first report of Rhizopus rot caused by R. oryzae in seedlings of grafted cucumber on pumpkin rootstock in South Korea.  相似文献   

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Effects of chitosan, oligochitosan and the essential oils of clove and cinnamon were evaluated on hyphal morphology, cell wall thickness, minimum medium pH changes and respiration of Rhizopus stolonifer. Changes in hyphal morphology were observed due to chitosan or oligochitosan treatment in this fungus. Mycelial branching, abnormal shapes and swelling were showed on hyphae of R. stolonifer treated with chitosan, whereas the development of hyphae was markedly inhibited by the effect of oligochitosan. Clove and cinnamon oils caused few morphological changes in the hyphae of R. stolonifer. Cell wall thickness was increased approximately 2‐ to 3‐fold by effect of chitosan, oligochitosan and the essential oil of clove. R. stolonifer grown in minimum medium generated a decrease in the medium's pH. However, the addition of chitosan or oligochitosan caused increases in pH of medium culture. The highest pH value (5.4) was observed in the presence of chitosan. The respiration of R. stolonifer was stimulated at low concentrations of chitosan, oligochitosan or essential oils. Significant changes in morphology and physiology of this fungus were demonstrated by the effect of all evaluated compounds. The most important changes were induced on cells of R. stolonifer treated with chitosan and oligochitosan.  相似文献   

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A potential antagonist, Bacillus sp. LYLB4 isolated from pear fruits, was tested for its antifungal activity against postharvest pear pathogens. LYLB4 had a remarkable antifungal effect on Botryosphaeria dothidea. Although it showed a weak inhibition effect on the growth of Rhizopus stolonifer on potato dextrose agar (PDA) plates, LYLB4 almost completely destroyed R. stolonifer during direct contact in potato dextrose broth (PDB). LYLB4 treatment was able to significantly reduce disease incidence (by 68.9% and 100%, respectively) and lesion diameter (by 68.7% and 100%, respectively) of ring rot caused by B. dothidea and soft rot caused by R. stolonifer in pears. LYLB4 also suppressed several other phytopathogens in vitro, suggesting a broad‐spectrum antagonistic activity against fungal pathogens. 16S rRNA and gyrA sequence analysis indicated that LYLB4 is closely related to B. velezensis. Genome mining indicated that LYLB4 had 11 secondary metabolites encoding clusters, but that the surfactin and fengycin gene clusters may not be functional because of a large deletion. Matrix‐assisted laser desorption ionization‐time of flight mass spectra (MALDI‐TOF‐MS) demonstrated that iturins were the major lipopeptides, and that C16/C17 Bacillomycin D synthesis was stimulated when LYLB4 was co‐cultured with B. dothidea compared to the control. Overall, these results demonstrate that the main biocontrol mechanism adopted by LYLB4 could be through the production of toxic metabolites and direct contact with pathogens.  相似文献   

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【目的】桃果实易受匍枝根霉(Rhizopus stolonifer)侵染引起软腐病,导致果实采后腐烂损失严重。目前人工合成的化学杀菌剂是控制桃果实采后病害的主要方法,但长期使用容易带来食品安全隐患、病原菌抗药性和环境污染等问题。通过研究生物源抑菌成分1-辛烯-3-醇对桃果实软腐病的控制作用,为减少化学农药使用和控制采后桃果实软腐病提供理论基础。【方法】使用1-辛烯-3-醇熏蒸接种匍枝根霉(R.stolonifer)后的桃果实,对果实抗病相关基因表达和酶活性进行测定。通过离体试验,研究1-辛烯-3-醇熏蒸对匍枝根霉(R.stolonifer)菌丝和孢子的影响。【结果】55.80μg/mL 1-辛烯-3-醇熏蒸处理可以显著降低桃果实的发病率和病斑直径(P<0.05),提高几丁质酶(chitinase,CHI)和β-1,3葡聚糖酶(β-1,3-glucanase,GLU)的活性以及病程相关基因非表达子1(nonexpressor of pathogenesis-related protein 1,NPR1)、病程相关蛋白1(pathogenesis-related protein 1,PR1)、CHI和GLU的基因表达量。离体试验结果显示,1-辛烯-3-醇可抑制平板上匍枝根霉(R.stolonifer)菌丝的生长,使菌丝体细胞结构遭到破坏,同时显著降低麦角固醇含量(P<0.05),抑制孢囊孢子的萌发和芽管伸长,并通过破坏孢子的膜结构,引起活性氧(reactive oxygen species,ROS)暴发与线粒体损伤。【结论】以上结果证实,1-辛烯-3-醇熏蒸处理不仅能直接破坏匍枝根霉(R.stolonifer)的菌丝与孢子,还可通过诱导桃果实的系统获得性抗性(systemic acquired resistance,SAR)抑制采后软腐病的蔓延。  相似文献   

7.
  总被引：1，自引：0，他引：1  
Experiments were conducted in North and South America during 2012–2013 to evaluate the use of lure combinations of sex pheromones (PH), host plant volatiles (HPVs) and food baits in traps to capture the oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), in pome and stone fruit orchards treated with sex pheromones. The combination of the sex pheromone of both species (PH combo lure) significantly increased G. molesta and marginally decreased C. pomonella captures as compared with captures of each species with either of their sex pheromones alone. The addition of a HPV combination lure [(E,Z)‐2,4‐ethyl decadienoate plus (E)‐β‐ocimene] or acetic acid used alone or together did not significantly increase the catch of either species in traps with the PH combo lure. The Ajar trap baited with terpinyl acetate and brown sugar (TAS bait) caught significantly more G. molesta than the delta trap baited with PH combo plus acetic acid in California during 2012. The addition of a PH combo lure to an Ajar trap significantly increased catches of G. molesta compared to the use of the TAS bait or PH combo lure alone in 2013. Female G. molesta were caught in TAS‐baited Ajar traps at similar levels with or without the use of additional lures. Ajar traps baited with the TAS bait alone or with (E)‐β‐ocimene and/or PH combo lures caught significantly fewer C. pomonella than delta traps with sex pheromone alone. Ajar traps with 6.4‐mm screened flaps caught similar numbers of total and female G. molesta as similarly baited open Ajar traps, and with a significant reduction in the catch of non‐targets. Broader testing of HPV and PH combo lures for G. molesta in either delta or screened or open Ajar traps is warranted.  相似文献   

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The anthracnose stalk rot of corn (ASR), caused by Colletotrichum graminicola, is a major disease of this crop and occurs in most Brazilian regions where corn is grown. Despite its widespread occurrence, there are no estimates of the effect of ASR on the yield of corn under the Brazilian conditions. In this study, we evaluated the effect of ASR on corn hybrids yield. Two experiments were conducted (first crop 2007/2008 and second crop, 2009) in areas with a history of occurrence of leaf anthracnose and ASR. Five hybrids were evaluated in the first and second crops: AG1051, BRS 1001, BRS 1010, BRS 1035, P30F80 and BRS 1010, 2B710, P30F80, DKB390, BRS 1035, respectively. At harvest, we evaluated the incidence of plants with anthracnose stalk rot (IPASR), and we selected pairs of healthy and diseased plants to quantify the effect of ASR in the ear weight (EW), grain weight (GW) and the weight of a sample containing 100 kernels (W100). The IPASR was higher in the hybrid BRS 1010 (21.87 and 45.28%, first and second crops, respectively). The EW, GW and W100 were lower in diseased plants in all hybrids. The mean weight loss in the first season was EW 29.03%, GW 27.83% and W100 17.08%, and the second season was EW 27.75%, GW 25.60% and W100 16.99%. The most affected hybrids with weight loss in the first crop were AG1051 (EW 34.31%, GW 33.05%, W100 19.96%) and BRS 1035 (EW 34.74%, GW 34.65%, W100 22.31%). In the second crop, were P30F80 (EW 30.72%, GW 30.92%, W100 19.24%), DKB390 (EW 30.61%, GW 29.81%) and 2B710 (W100 19.27%). Corn yield was strongly affected by ASR.  相似文献   

12.
  总被引：2，自引：0，他引：2  
Studies were conducted in Chile and the United States to compare the attractiveness of various commercial sex pheromone lures and two experimental lures for oriental fruit moth, Grapholita molesta (Busck), in peach orchards treated with or without sex pheromone dispensers. The experimental lures contained the three‐component sex pheromone blend of G. molesta: Z‐8‐dodecenyl acetate, E‐8‐dodecenyl acetate and Z‐8‐dodecenol (Z8‐12:OH), and the sex pheromone of codling moth, Cydia pomonella (L.), (E,E)‐8,10‐dodecadien‐1‐ol, (codlemone). Commercial lures varied in their substrate, initial loading and blend ratio of components. Significant differences in male catches were found among commercial lures in orchards treated with or without sex pheromone dispensers. Experimental lures with the addition of codlemone significantly increased the catches of G. molesta using lures loaded with 0%, 1% or 5% Z8‐12:OH in the G. molesta blend compared with the same ratio of components in just the G. molesta blend. The experimental lures were significantly more attractive than all commercial lures in the untreated orchard. However, moth catch with the experimental lures in the sex pheromone‐treated orchard was only intermediate among all of the lures tested. These findings highlight the need to develop more effective and standardized lures that can be used in trap‐based monitoring programme for this important pest.  相似文献   

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Blackleg and soft rot of potato cause economic loss through reduced yield and quality. The causal agents of bacterial blackleg and soft rot of potato were identified based on biological data and sequence analyses of the 16S rDNA gene. Between 2016 and 2018, diseased potato stems and tubers were collected in Chai Prakan District, Chiang Mai Province, and Chiang Khum District, Pa Yao Province. The symptoms included black stem lesions, soft rot on tubers, wilting, break down of the stem vascular ring and foliar yellowing. Of 13 bacterial isolates, five were identified as Pectobacterium carotovorum subsp. brasiliense, four‐Dickeya dadantii, two‐Pseudomonas putida and two‐Bacillus altitudinis. Pathogenicity tests of P. carotovorum subsp. brasiliense and D. dadantii resulted in lower leaves turning yellow and wilting followed by blackleg symptoms on lower stems and maceration of tuber tissue. Symptoms caused by P. putida were yellowing and wilting of leaves. B. altitudinis caused yellowing of the lower leaves and wilting followed by drying of leaf tissue. This is a first report of these bacterial pathogens causing blackleg and soft rot of potato in Thailand.  相似文献   

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Male and female moth catches of Grapholita molesta (Busck) in traps were evaluated in stone and pome fruit orchards untreated or treated with sex pheromones for mating disruption in Uruguay, Argentina, Chile, USA, and Italy from 2015 to 2017. Trials evaluated various blends loaded into either membrane cup lures or septa. Membrane lures were loaded with terpinyl acetate (TA), acetic acid (AA) and (Z)‐3‐hexenyl acetate alone or in combinations. Two septa lures were loaded with either the three‐component sex pheromone blend for G. molesta alone or in combination with codlemone (2‐PH), the sex pheromone of Cydia pomonella (L). A third septum lure included the combination sex pheromone blend plus pear ester, (E,Z)‐2,4‐ethyl decadienoate (2‐PH/PE), and a fourth septum was loaded with only β‐ocimene. Results were consistent across geographical areas showing that the addition of β‐ocimene or (Z)‐3‐hexenyl acetate did not increase moth catches. The addition of pear ester to the sex pheromone lure marginally increased moth catches. The use of TA and AA together significantly increased moth catches compared with the use of only one of the two components. Traps with the TA/AA lure outperformed the Ajar trap baited with a liquid TA plus sugar bait. The emission rate of AA was not a significant factor affecting the performance of the TA/AA lure. The addition of TA/AA significantly increased moth catches when combined with the 2‐PH lure. The TA/AA lure also allowed traps to catch both sexes. Catch of C. pomonella with the 2‐PH lure was comparable to the use of codlemone; however, moth catch was significantly reduced with the 2‐PH/PE lure. Optimization of these complex lures can likely further improve managers’ ability to monitor G. molesta and help to develop multispecies tortricid lures for use in individual traps.  相似文献   

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We report a rapid diagnosis of soya bean (Glycine max L.) root rot caused by Fusarium culmorum, using a loop‐mediated isothermal amplification (LAMP) assay. We used the CYP51C gene sequence to design LAMP assay primers specific for F. culmorum. The LAMP assay amplified the target gene efficiently in 60 min at 63°C. The sensitivity of the assay was 100 pg/μl of genomic DNA. Among the tested soya bean pathogens, a positive colour (sky blue) was only observed in the presence of F. culmorum with the addition of hydroxynaphthol blue (HNB) dye prior to amplification, whereas other species isolates showed no colour change. Suspected diseased soya bean samples collected in the field from Jiangsu, Shandong and Anhui provinces and Beijing were diagnosed successfully using the LAMP assay reported here. This study provides a new and readily available method for rapid diagnosis of soya bean root rot caused by F. culmorum.  相似文献   

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To exploit natural products for plant disease control, the essential oil of Syzygium aromaticum (L.) Merr. & Perr. (clove) was investigated for its antifungal activity against Rhizopus stolonifer and Fusarium solani, the postharvested yam tuber rot pathogens. The essential oil was obtained by hydrodistillation using a Clevenger‐type apparatus. The chemical composition of the oil was determined by gas chromatography and gas chromatography coupled with mass spectrometry. Antifungal activities of the oil were tested in vitro against mycelia growth and spores germination. In situ tests were conducted on healthy yam tubers, and necrosis symptoms were assessed. Results showed that eugenol (79.4%), eugenylacetate (9.2%) and isocaryophyllene (7.0%) were the major components. The oil exerted antifungal activities with total inhibition (TI) of the mycelia growth of R. stolonifer and F. solani was recorded at 200 and 300 ppm, respectively, while TI of spores germination was recorded at 31.25 and 250 ppm, respectively. For the standard fungicide (Ridomil®), TI value of mycelia growth was 1600 ppm for the both pathogens, while TI of spores germination were 200 ppm and 1600 ppm, respectively, for Rhizopus and Fusarium. In situ tests showed complete inhibition of yam tuber rot when the essential oil was applied at 2000 ppm for preventive tests. This oil also reduced significantly (P ≤ 0.05) necrosis development on yam tuber for curative test at the same concentration. Total inhibition of the necrosis by Ridomil (3000 ppm) was observed only for Rhizopus on preventive test. There were positive correlations between the oil concentration and the reduction of necrosis cause by R. stolonifer and F. solani. These findings showed that clove essential oil may serve as environmental friendly bio‐fungicide for the management of postharvest yam tuber rot.  相似文献   

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We have explored the fungal diversity in asymptomatic twigs of apple, peach, pear and blueberry trees, with the objective of discerning between true endophytes and latent pathogens. Several fungal genera containing known bark pathogens were found. Seven Diaporthe species—D. oxe, D. infecunda, D. serafiniae, D. phaseolorum, D. terebinthifolii, D. foeniculina and D. brasiliensis—were identified, along with Botryosphaeria dothidea, Neofusicoccum parvum, Neofusicoccum australe, Cytospora sp., Cytospora acaciae and Pestalotiopsis spp. A pathogenicity trial was undertaken to determine the role of these species on apple, pear, blueberry and peach shoots. Diaporthe brasiliensis, D. foeniculina, Diaporthe inconspicua, D. terebinthifolii, Diaporthe sp.1, Cytospora‐like isolates and Pestalotiopsis spp. isolates produced no lesions on inoculated shoots, suggesting that they could be considered true endophytes on their respective hosts. Meanwhile, some of the isolates of Diaporthe—D. oxe, Diaporthe sp.2, D. infecunda and D. serafiniae, B. dothidea, N. parvum and N. australe could be regarded as latent pathogens in their respective hosts as they produced sunken cankers and necrosis on inoculated shoots. These results demonstrate that apple, pear, blueberry and peach healthy shoots can host many known endophytic fungi along with potential wood disease‐causing fungi that should be regarded as latent pathogens.  相似文献   

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Stem rot was recorded on Orobanche aegyptiaca in Shihezi City, Xinjiang Uygur Autonomous Region, China from 2010 to 2011. The pathogen was isolated repeatedly from the infected stems and was identified as Rhizopus oryzae based on morphology, cultural features and molecular analysis. Koch's postulates were supported by pathogenicity tests conducted on healthy plants grown on processing tomato and melon. To our knowledge, this paper is the first to report the occurrence of R. oryzae stem rot on O. aegyptiaca.  相似文献   

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