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1.
Biological Control to Protect Watermelon Blossoms and Seed from Infection by Acidovorax avenae subsp. citrulli 总被引：1，自引：0，他引：1
ABSTRACT The efficacy of biological control seed treatments with Pseudomonas fluorescens (A506), Acidovorax avenae subsp. avenae (AAA 99-2), and an unidentified gram-positive bacterium recovered from watermelon seed (WS-1) was evaluated for the management of bacterial fruit blotch (BFB) of watermelon. In growth chamber and greenhouse experiments, seed treated with AAA 99-2 displayed superior disease suppression, reducing BFB transmission by 96.5%. AAA 99-2, P. fluorescens A506, and Kocide also suppressed the epiphytic growth of A. avenae subsp. citrulli when applied to attached watermelon blossoms 5 h prior to inoculation. Watermelon blossom protection reduced seed infestation by A. avenae subsp. citrulli. From blossoms treated with 0.1 M phosphate buffered saline (PBS), 63% of the resulting seed lots were infested with A. avenae subsp. citrulli. In contrast, for blossoms protected with WS-1, Kocide, P. fluorescens A506, and AAA 99-2, the proportion of infested seed lots were 48.3, 21.1, 24.1, and 13.8%, respectively. The effect of blossom treatments on seed lot infestation was statistically significant (P = 0.001) but WS-1 was not significantly different from PBS. These findings suggest that blossom protection with biological control agents could be a feasible option for managing BFB. 相似文献
2.
ABSTRACT To assess the diversity of Acidovorax avenae subsp. citrulli, 121 strains from watermelon, cantaloupe, and pumpkin were compared using pulse field gel electrophoresis of SpeI-digested DNA and gas chromatographic analysis of fatty acid methyl esters. Twenty-nine unique DNA fragments resulted from DNA digestion, and 14 distinct haplotypes were observed. Based on cluster analysis, two subgroups, I and II, were recognized, which accounted for 84.8% (eight haplotypes) and 15.2% (six haplotypes) of the strains, respectively. Results of cellular fatty acid analysis varied quantitatively and qualitatively for the A. avenae subsp. citrulli strains and supported the existence of the two subgroups. Group I includes strains from cantaloupe and pumpkin as well as the ATCC type strain, which was first described in the United States in 1978, whereas group II represents the typical watermelon fruit blotch-causing strains that appeared in the mainland United States in 1989. Knowledge of the two A. avenae subsp. citrulli groups may be useful in screening for watermelon fruit blotch resistance. 相似文献
3.
New subspecies-specific primers for the detection of Acidovorax avenae subsp. citrulli ( Aac ), the seedborne bacterium which causes bacterial fruit blotch of cucurbits, were designed based on PCR fragments obtained in ERIC- and BOX-PCR profiles of Aac strains. PCR with both primer sets identified 30 strains from different locations and hosts, but did not amplify DNA from other closely related species and subspecies assessed, with the exception of DNA of one strain of A. avenae subsp. avenae , which was amplified by one of the primer sets, named BX-S. This primer set, based on a BOX-PCR fragment, performed under high-stringency conditions without losing its detection sensitivity. The primers were also evaluated for their ability to detect the pathogen in contaminated watermelon and melon seed samples. The BX-S primers facilitated the detection of the pathogen from washings of 5000-seed samples with 0·02% infestation. This primer set was also assessed for detection using immunomagnetic separation polymerase chain reaction (IMS-PCR) and was shown to be as sensitive as a previously described primer set (AACF2/R3), detecting 0·02% infestation in seed samples. This highly specific and sensitive primer set could be used to improve PCR-based detection of this important pathogen. 相似文献
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种子引发处理对无籽西瓜幼苗生长的影响和对细菌性果斑病菌消毒的效果 总被引：2，自引：0，他引：2
种子出苗率低和传带细菌性果斑病菌是制约三倍体无籽西瓜生产的主要原因。本试验利用KMnO4、CuSO4和ZnSO4的不同浓度溶液对无籽西瓜种子进行不同时间引发处理, 通过滤纸发芽试验, 观测其对种子发芽和幼苗生长的促进作用;借助平板法测定引发溶液对细菌性果斑病菌FC247的抑制作用, 免疫凝聚试纸条和传统PCR检测引发处理对种子人工接菌FC247的消毒效果。结果表明:0.1% CuSO4溶液引发处理4 h和0.2% ZnSO4溶液引发处理24 h, 分别比未引发处理的无籽西瓜种子发芽率提高71.1%和73.3%, 并能显著提高发芽整齐度和幼苗素质;同时, 引发溶液对细菌性果斑病菌有显著抑制作用, 并对人工接菌种子表现出-定程度的消毒效果。 相似文献
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甜瓜细菌性果斑病菌致病性突变体筛选与hrcR基因的克隆 总被引：2，自引：0，他引：2
细菌性果斑病(Bacterial Fruit Blotch,BFB)是西瓜和甜瓜的重要病害。本实验从发病甜瓜果实上分离得到致病菌株MH21,经鉴定为燕麦食酸菌西瓜亚种(Acidovorax avenae subsp. citrulli)。利用转座子Mini-Tn5构建MH21菌株的突变体库,Southern印迹杂交结果显示Mini-Tn5在菌株MH21染色体上可随机、单拷贝插入。通过浸种处理甜瓜种子进行突变体的致病性检查,筛选得到1株致病性完全丧失的突变体M543。对M543中转座子插入基因的克隆和测序表明其突变基因为燕麦食酸菌Ⅲ型分泌系统(TTSS)中的保守基因hrcR。推测菌株MH21中hrcR基因编码的蛋白定位于细菌内膜,是分泌通道主要成分之一。hrcR基因互补菌株的致病性检查结果显示其致病力恢复到野生型的84%。研究同时发现hrcR基因突变后MH21菌株丧失了在烟草上诱导过敏性坏死反应的能力。本研究从遗传学角度说明TTSS是西甜瓜果斑病菌致病性的重要因子。 相似文献
8.
Watermelon seeds can become infested by Acidovorax citrulli, the causal agent of bacterial fruit blotch (BFB) of cucurbits via penetration of the ovary pericarp or by invasion of the pistil. This study investigated the effect of these invasion pathways on A. citrulli localization in seeds. Seed samples (n = 20 or 50 seeds/lot) from pistil- and pericarp-inoculated lots were dissected into testa, perisperm-endosperm (PE) layer, and embryo tissues and tested for A. citrulli by species-specific polymerase chain reaction (PCR) and by plating on semiselective media. Less than 8% of the testa samples were A. citrulli-positive regardless of the method of seed inoculation. Additionally, the difference in percentages of contaminated testae between the two seed lot types was not significant (P = 0.64). The percentage of A. citrulli-positive PE layer samples as determined by real-time PCR assay was significantly greater for seeds from pistil-inoculated lots (97%) than for seeds from pericarp-inoculated lots (80.3%). The mean percentage of A. citrulli-positive embryo samples was significantly greater for seeds from pistil-inoculated lots (94%) than for seeds from pericarp-inoculated lots (≈8.8%) (P = 0.0001). Removal of PE layers and testae resulted in a significant reduction in BFB seed-to-seedling transmission percentage for seeds from pericarp-inoculated lots (14.8%) relative to those from pistil-inoculated lots (72%). Additionally, using immunofluorescence microscopy, A. citrulli cells were observed in the PE layers and the cotyledons of pistil-inoculated seeds but only in the PE layers of pericarp-inoculated seeds. These results suggest that pericarp invasion results in superficial contamination of the testae and PE layers while pistil invasion results in the deposition of A. citrulli in seed embryos. 相似文献
9.
由嗜酸菌属西瓜种(Acidovorax citrulli)引起的西瓜细菌性果斑病是西瓜等葫芦科作物上的一种极具毁灭性的病害,该病原细菌可以由种子携带传播。本研究通过直接研磨种子,用双抗体夹心酶联免疫吸附测定法(DAS-ELISA)和免疫捕捉聚合酶链式反应法(IC-PCR)对进境的西瓜种子进行检测,并且对PCR产物进一步克隆测序。结果表明,在DAS-ELISA产生阳性结果的样品中,IC-PCR结果也产生阳性。序列分析表明,该序列与已知的该病菌16S rRNA基因的相应序列具有100%同源性。因此,2006年这批来自台湾的西瓜种子携带有嗜酸菌属西瓜种(Acidovorax citrulli)。 相似文献
10.
R.B. Mabagala 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(2):175-181
Surface and internal populations of Xanthomonas campestris pv. phaseoli, causal agent of common bacterial blight of bean, on and in flower buds, blossoms and pods of seven bean (Phaseolus vulgaris) genotypes were studied. Bean plants were grown in the field and artificially inoculated at the seedling stage (18 days old). The pathogen was recovered in high numbers from flower buds, blossoms, pods and seed of both resistant and susceptible bean genotypes. Significant differences (P = 0.05) in population levels of X. c. pv. phaseoli between stages of reproductive tissue development were observed. Infected seed from resistant bean genotypes had no visible symptoms. Such seed may play an important role in the epidemiology of common bacterial blight because they are difficult to detect and may occur at low frequency in seed lots, as was the case in the current study. 相似文献
11.
由西瓜嗜酸菌(Acidovorax citrulli)引起的细菌性果斑病是一种毁灭性的种传病害,可为害多种葫芦科作物并造成重大经济损失。该病原菌为检疫性有害生物,种子带菌是田间病害发生的最重要初侵染来源,因此,种子健康检测成为病害综合防控过程中的重要环节。Bio-PCR是当前种子携带细菌检测的常用方法,而特异性引物的选择和使用是检测的关键。本研究使用已报道的7对引物对17株西瓜嗜酸菌、10株嗜酸菌属其它种的菌株和6株其它属的植物病原细菌进行了Bio-PCR检测,筛选出对西瓜嗜酸菌特异性最好的引物为SEQID4m/SEQID5。研究表明:使用该引物对西瓜嗜酸菌MH21纯菌菌悬液的检测限度为102 CFU·mL-1;在人工添加菌悬液的模拟带菌西瓜种子中,使用ASCM和EBBA两种半选择性培养基结合引物SEQID4m/SEQID5进行Bio-PCR检测,ASCM对种子中带菌量的检测限度可达到0.01 CFU·g-1,EBBA对种子中带菌量的检测限度为0.1 CFU·g-1。 相似文献
12.
黄瓜绿斑驳花叶病毒对西瓜产量、品质及种子带毒的影响 总被引：1，自引：0，他引：1
研究了西瓜不同时期接种黄瓜绿斑驳花叶病毒(Cucumber green mottle mosaic virus,CGMMV)后对其生长、产量、品质和种子带毒的影响。西瓜植株接种CGMMV越早其生长受到抑制越明显,砧木期、嫁接后定植前、定植期、压蔓期、授粉期各处理的株高、叶片数、叶片长与对照相比差异极显著(p0.01),而结瓜以后接种CGMMV对西瓜生长状况无显著影响。压蔓期前3个生育期接种该病毒,西瓜产量损失分别为56.49%、55.48%和51.14%。而压蔓期以后接种该病毒,西瓜产量损失与对照相比仍分别降低17%、13.1%和14.35%。关于倒瓤情况,压蔓期前接种该病毒可导致西瓜果实100%倒瓤,压蔓期、授粉期接种处理西瓜倒瓤率分别为48%和34%,即使结瓜后再接种病毒西瓜倒瓤率仍高达18%。血清学检测表明,压蔓期前接种的西瓜其果肉和种子均携带CGM-MV,带毒率达100%;结瓜后再接种CGMMV西瓜种胚和果肉的带毒率仍然高达64%。检测种胚和果肉病毒含量表明,接种时期越早病毒含量越高,但结瓜后接种仍有较高的病毒含量,种胚和果肉的病毒含量分别达5.98 mg/mL和5.64 mg/mL。 相似文献
13.
B. Dutta H. Sanders D. B. Langston C. Booth S. Smith R. D. Gitaitis 《Plant pathology》2014,63(5):1130-1137
Long‐term survival of Acidovorax citrulli in citron melon (Citrullus lanatus var. citroides) seeds was investigated. Citron melon seed lots infected with A. citrulli were generated in the field by inoculating either the pistils (stigma) or pericarps (ovary wall) of the female blossoms. Seventeen A. citrulli isolates from 14 different haplotypes belonging to two different groups (group I and II) were used for inoculation. After confirming that 100% of seed lots were infected, they were stored at 4°C and 50% RH for 7 years. After storage, the viability of A. citrulli cells from individual lots was determined by plating macerated seeds on semiselective medium as well as growing seeds for 14 days and scoring for bacterial fruit blotch symptoms. The type of A. citrulli isolate (group I or group II) used did not significantly influence bacterial survival. However, A. citrulli survival was significantly greater in seed lots generated via pistil inoculation (52·9 and 29·4%) than via pericarp inoculation (23·5 and 17·6%). Repetitive extragenic palindrome (rep)‐PCR on A. citrulli isolated from citron melon seed lots after storage displayed similar fingerprinting patterns to those of the reference strains originally used for blossom inoculation, indicating that cross‐contamination did not occur. The results indicate that A. citrulli may survive/overwinter in citron melon seeds for at least 7 years and bacterial survival in seed was influenced more by method of blossom inoculation than by the type of bacterial isolate. 相似文献
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本文利用群体感应信号报告菌Agrobacterium tumefaciens NTL4(pZLR4),在LB报告平板上对燕麦食酸菌西瓜亚种的19个菌株进行了初步检测,发现18个菌株有群体感应信号产生.用琼脂条法对菌株Pslb-94进一步检测,证实菌株Pslb-94存在群体感应系统.提取了该菌株信号物质,反相薄层层析(TLC)检测证明该菌株能产生群体感应信号分子. 相似文献
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ABSTRACT We evaluated effects of both physical and biological components of the environment on growth of Pantoea agglomerans on inoculated pear and apple blossoms and on spread of the bacterium to blossoms on non-inoculated trees. The center three rows of 0.35- to 0.5-ha blocks of four pear cultivars and four apple cultivars were sprayed with a suspension of streptomycin-resistant P. agglomerans strain C9-1S (C9-1S) at 20 to 60% and 60 to 90% bloom. Cultivars were chosen to create a sequence of continuous bloom from late March (d'Anjou pear) through mid-May (Red Rome apple). Each cultivar block was quartered into plots; two plots were treated twice with streptomycin sulfate near mid- and full bloom to suppress populations of indigenous bacterial epiphytes and the other two plots were treated with water. Colonization of blossoms by C9-1S and by indigenous bacterial epiphytes were monitored on inoculated trees and along transects of noninoculated trees. Immediately after spraying, C9-1S was detected principally on blossoms sampled from inoculated trees. As bloom progressed, trees up to 18 m from inoculated trees had high proportions of blossoms colonized by C9-1S. Streptomycin significantly (P 相似文献
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浙江水稻稻种病原细菌多样性研究 总被引：9，自引：0，他引：9
1997~2000年间对以浙江平原、丘陵及山区为主的稻种病原细菌开展了种类、频率及传病率的研究。从303份稻种样本中分离出3906个菌株,经菌落形态、细菌学、致病性测定后获得201个致病或弱致病菌(占总数的5.15%)。选出致病及非致病代表菌株299个连同23个对照菌株用Biolog进行证实。结果表明种子上所带的病原细菌涉及到6个致病细菌种和5个弱致病种。平原稻区存在较多致病细菌种,山区较少,但两地均以弱致病细菌种占优势;丘陵的强致病细菌种的分离频率显著高于平原与山区。在稻种上携带的11个细菌种中,人工接种和自然感染的病稻种均能引起传病的有Xanthomonas oryzae pv.oryzicola,Pseudomonas fuscovaginae及Acidovorax avenae subsp.avenae. 相似文献
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甘肃省南瓜及西葫芦小西葫芦黄花叶病毒病鉴定 总被引：1，自引：0，他引：1
利用双抗夹心酶联免疫吸附测定(DAS-ELISA)的方法对甘肃出入境南瓜、西葫芦种子及采自河西地区显症病株叶片进行检测,在种子及病叶组织中均检测到ZYMV病毒,其中南瓜种子带毒批次占12.5%,西葫芦种子带毒批次占11.8%。根据已报道的小西葫芦黄花叶病毒(Zucchini yellow mosaic virus)基因组核苷酸序列,设计引物扩增其外壳蛋白(CP)基因,以ELISA阳性种子或病叶组织总RNA为模板,进行RT-PCR扩增,对预期大小的扩增产物进行测序,结果表明扩增获得的核苷酸序列与世界各地的ZYMV分离物CP基因具有高度一致性,综合ELISA检测和RT-PCR的结果,确定南瓜、西葫芦种子可携带ZYMV,且ZYMV是侵染甘肃瓜类作物的重要病毒种类。 相似文献
18.
The influence of inoculum preparation on the establishment of bacterial antagonists that suppress fire blight and Erwinia amylovora on blossoms was evaluated. Aqueous suspensions of Pseudomonas fluorescens A506, E. herbicola C9-1R, or E. amylovora 153N were prepared from cells harvested from the surface of an agar medium or from cells that were lyophilized after culture under similar conditions. Bacterial suspensions (1 x 10(8) CFU/ml) were sprayed on pear and apple trees at 50% bloom near midday. The incidence of recovery (proportion of blossoms containing detectable populations) and the population sizes of the bacteria on individual blossoms with detectable populations were followed over a period of several days. Fluorescent microspheres (1 mum in diameter) were added to sprays at a concentration of 1 x 10(7) microspheres per ml to mark blossoms that were open during application of bacteria. After dilution-plating, the stigmas and styles of each blossom were examined for the presence of microspheres with an epifluorescence microscope. In three of five trials, bacteria applied as suspensions of lyophilized cells were recovered from a greater proportion of blossoms than bacterial cells harvested directly from culture media. Every blossom harvested within 6 days after spraying had microspheres present on the surfaces of the styles and stigmas; thus, lack of establishment of detectable populations, rather than escape of blossoms from spray inoculation, accounted for the differences in proportion of blossoms colonized by the different preparations of bacteria. The use of lyophilized cells in field trials decreased variability in the establishment of bacteria on blossoms. 相似文献
19.
瓜类果斑病菌(Acidovorax avenae subsp.citrulli,Aac)是瓜类作物上重要的病原细菌,为我国进境植物检疫性有害生物。胶体金免疫层析试纸条方便快捷,应用广泛。该方法使用不当会出现假阳性问题,仅适用于病原菌的初筛检测。本研究将Aac胶体金免疫层析方法(GICA)与PCR技术相结合,建立了GICA-PCR检测方法。检测结果表明,该方法在蛋白与核酸2个层面上从发病西瓜叶片上检测到瓜类果斑病菌,有效解决了试纸条检测的假阳性问题,提高了瓜类果斑病菌检测的准确性,值得推广应用。 相似文献
20.
细菌性果斑病和角斑病是葫芦科作物两大重要细菌病害,病原菌分别为西瓜嗜酸菌Acidovorax citrulli和丁香假单胞菌黄瓜致病变种Pseudomonas syringae pv.lachrymans。两种菌均可通过种子、种苗带菌进行远距离传播。种子检测是预防和控制这两种病害发生的首要环节。本研究应用微滴数字PCR技术(droplet digital PCR,ddPCR)建立了同时检测种子携带西瓜嗜酸菌和丁香假单胞菌的方法。结果显示:两种细菌菌悬液和DNA样品等浓度混合时,ddPCR能同时检测到两种靶标菌的最低混合菌悬液浓度和最低DNA浓度分别为103 cfu/mL和10-3 ng/μL,其检测灵敏度是平行测试的real-time PCR方法的10倍;对于非等浓度混合的菌悬液和DNA样品,两种靶标菌菌悬液按浓度比1∶1000(103∶106 cfu/mL)混合或其DNA浓度比为1∶10000(2.28×10-3 ng/μL∶22.8 ng/μL)条件下,ddPCR可检测到低浓度的靶标菌,检测灵敏度同样是real-time PCR的10倍。此外,在人工接菌种子测试中,西瓜、甜瓜单粒种子平均带菌量105~106 cfu/粒时,ddPCR方法可检测到带菌率0.2%(n=500)的西瓜、甜瓜种子样品。将分别携带两种菌的种子按比例1∶10混合时ddPCR方法可以准确检出浓度相对低的靶标菌;而使用相同检测引物的real-time PCR检测方法则只能检出西瓜嗜酸菌和丁香假单胞菌带菌率分别为0.2%和2%(n=500)的甜瓜种子混合样品中的西瓜嗜酸菌,未能稳定检出丁香假单胞菌。综上所述,本研究基于ddPCR技术建立了可同时检测两种重要葫芦科种传细菌的方法,检测结果稳定可靠,丰富了当前种传病原细菌的检测技术体系。 相似文献