桃细菌性穿孔病的识别与防治

<正>桃穿孔病是桃树上发生最为普遍的叶部病害,穿孔病有细菌性穿孔病和真菌性穿孔病,其中以细菌性穿孔病为害最严重。在排水不良、湿度大、红蜘蛛发生严重的桃园,最容易发生该病。发病重的,引起大量落叶,枝梢枯死,果面密布疤痕,影响果实外观,给果农造成较大的经济损失。笔者介绍该病的识别与防治方法,供生产上参考。     

大棚温室油桃穿孔病的发生及防治策略

桃树穿孔病是大棚温室油桃生产上的主要病害之一 ,在夏县桃树穿孔病分为细菌性穿孔病、真菌性霉斑穿孔病和真菌性褐斑穿孔病等 3种 ,而以细菌性穿孔病危害最甚。在多雨年份 ,排水不良 ,湿度大或红蜘蛛多时发生严重 ,常引起早期落叶、新梢枯死 ,削弱树势 ,降低果品的产量和质量。近年来在油桃产区 ,年年都有发生 ,2 0 0 2年发生面积达 333hm2 ,发病率达 30 %～ 4 0 % ,严重制约了桃树的经济效益。1　细菌性穿孔病1.1　发病症状桃细菌性穿孔病 ,主要危害叶片 ,其次是新梢和果实。1.1.1　叶片症状　叶片发病初期为水渍状浅褐色小斑点 ,其周围有…     

氨基寡糖素对桃细菌性穿孔病的防治效果及增产作用研究

为明确氨基寡糖素5%水剂对桃细菌性穿孔病的防治效果和增产作用,特进行了相关试验调查研究。结果表明,在桃树上喷施氨基寡糖素5%水剂后,对桃树主要病害桃细菌性穿孔病的防效可达63%以上,与单独使用常规化学药剂防效基本相等,具有防病、抗病、减少化学农药使用,保护环境的效果;同时可提高果实外观品质,增产率在7%左右。可在桃树生产中大面积广泛使用。     

瓜类细菌性果斑病研究进展

瓜类细菌性果斑病是发生在甜瓜、西瓜等葫芦科植物上的一种严重的世界性病害,此病是典型的种传细菌性病害,病原为嗜酸菌属西瓜种(Acidovorax citrulli)。本文围绕瓜类细菌性果斑病菌的分离检测、致病机理、遗传多样性及防治等方面的研究进展作一概述,阐明了瓜类细菌性果斑病的研究现状。     

樱桃苗期病虫害防治技术

1樱桃细菌性穿孔病 1.1症状识别樱桃细菌性穿孔病菌为甘蓝黑腐黄单胞杆菌桃穿孔致病型(Xanthomonas can pestris PV.pruni).侵染叶片后,初呈半透明水渍状淡褐色小点.后扩大成圆形或多角形,不规则病斑,紫褐色或黑褐色,周围有一淡黄色晕圈.继而病斑干枯,易脱落穿孔.     

玉米细菌性茎腐病研究进展

玉米是重要的粮食、饲料和能源作物,是世界三大农作物之一.玉米细菌性茎腐病是玉米的常见病害,给我国玉米产业造成了较大的损失.为了更好地研究玉米细菌性茎腐病,本文梳理了该病害的症状与为害、病原学特性、流行规律、防治方法和致病机制等信息.玉米细菌性茎腐病菌寄主范围广,在土壤和病残体中存活时间长,且高温条件下果胶酶活性高.因此...     

马铃薯细菌性软腐病研究进展

细菌性软腐病是一种可引起果蔬严重危害的世界性植物病害,其频发已成为制约马铃薯种植业发展的瓶颈。本文基于国内外细菌性软腐病最新的研究报道,对马铃薯细菌性软腐病的病原鉴定、发病症状、致病机理、致病因子及防治措施等进行综述,并提出了进一步的研究方向,以期为马铃薯细菌性软腐病的相关研究提供科学参考。     

桃树细菌性穿孔病空间分布型和抽样技术研究

应用聚集度指标、Iwao的M*-M回归法、Taylor幂法则对桃树细菌性穿孔病的空间分布型及其抽样技术进行研究.结果表明,桃树细菌性穿孔病病叶的空间分布是随机趋向聚集的分布类型;分布的基本成分是个体群,聚集强度的大小与病叶密度的大小有关.造成这种分布的原因主要与病害自身特性或与环境因素共同作用所致.抽样方法中.以双对角线抽样方法为最佳,其次是平行线和棋盘式抽样.同时利用空问分布的有关参数,在允许误差的范围内给出了不同病叶密度下的理论抽样数.     

甘薯茎腐病的研究进展

甘薯茎腐病是由达旦提狄克氏菌Dickeya dadantii Samson et al.引起的细菌性甘薯病害,属于我国新发生病害,其蔓延迅速、防治困难,严重影响甘薯的品质和产量,已成为我国南方甘薯产区主要病害之一。文章对该病症状、病原菌分类、致病机制、全基因组测序概况和防治措施等方面的研究进展进行了综述,并指出了今后的研究方向。     

江苏省水稻品种细菌性条斑病抗性评价与病原菌致病力分化

采用针刺接种法,在水稻孕穗期接种3个不同致病型的细菌性条斑病菌,鉴定134个不同类型的水稻品种对细菌性条斑病的抗感性,并使用6个鉴别品种测定江苏徐淮地区82个细菌性条斑病菌的致病力.结果表明:粳稻品种对细菌性条斑病的抗性明显高于籼稻,常规稻和杂交稻对细菌性条斑病的抗性没有明显差异;根据病菌与鉴别品种的互作反应,将供试菌株区分为8个致病型,大多数菌株和鉴别品种表现为弱互作关系,少数菌株与鉴别品种存在强互作关系;第1致病型的菌株致病力强,6个鉴别品种均呈感病反应,并占供试菌株总数的40.2%.     

植物病害病斑形状的分形研究

应用分形理论中的周长面积法和曲线长度法分析了水稻纹枯病、玉米大斑病、玉米小斑病和桃细菌性穿孔病4种病害病斑形状的分形维数。结果表明 ,病斑形状具有明显的分形特征 ,其复杂性可以用分形维数的大小来表示 ,形状愈复杂 ,分形维数愈大 ,反之则愈小。周长面积法所得的分形维数分别是水稻纹枯病1.3385 ,玉米大斑病1.3799,玉米小斑病1.1633,桃细菌性穿孔病1.0470。曲线长度法所得的分形维数依次为水稻纹枯病1.3084,玉米大斑病1.2919,玉米小斑病1.0223,桃细菌性穿孔病1.0561。同一种病害中不同病斑之间分形维数变化范围表明了单个病斑之间形状差异。两种方法均可用于单个病斑或一类病斑分形维数的测算 ,但以周长面积法更好     

XopN-T3SS effector modulates in planta growth of Xanthomonas axonopodis pv. punicae and cell-wall-associated immune response to induce bacterial blight in pomegranate

Bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is an important disease of pomegranate. Most phytopathogenic strains in the Genera Xanthomonas secrete effector proteins by the type III secretion system (T3SS) to suppress pathogen-associated molecular pattern (PAMP)-triggered plant immunity (PTI). The T3SS effectors, referred to as Xanthomonas outer proteins (Xops), are known to be key factors required for bacterial growth and colonization in distinct eukaryotic hosts. Xap contains six Xop-effectors, namely XopC2, XopE1, XopL, XopN, XopQ and XopZ. In this study we analyzed xopN, a conserved effector in Xanthomonas, with reference to sequence identity and its role in governing bacterial growth, and virulence. The xopN of Xap shared maximum sequence identity (98.6%) with pathovar citri. Overlapping extension PCR and double crossing over based homologous recombination strategy was employed to generate a xopN null mutant (Xap ΔxopN) of Xap. A kanamycin gene was used to replace the xopN gene. XopN was required for maximal Xap pathogenicity in its natural host pomegranate. The detailed image analysis on blight lesions revealed 3 fold reduction in watersoaked areas on leaves infiltrated with mutant Xap ΔxopN compared to that of with wild Xap. The in planta population count of Xap ΔxopN was reduced approximately 32-fold relative to the wild strain indicating that xopN is required for maximal growth of Xap in pomegranate. In addition, the Xap ΔxopN mutant induced more callose deposition in infected pomegranate leaves. Taken together, the present study shows that XopN governs Xap growth and modulates cell-wall associated immune response in pomegranate.     

细菌性穿孔病危害对李树叶片蛋白质和氨基酸含量的影响

为判定细菌性穿孔病危害对李树叶片蛋白质和氨基酸含量变化的影响,以3个品种李树的病、健叶为试验材料,利用凯氏定氮仪及全自动氨基酸分析仪检测其蛋白质和氨基酸含量。结果显示,3个品种李树叶片受细菌性穿孔病危害后,蛋白质和氨基酸含量均出现了不同程度的下降,降幅与李树品种有关;细菌性穿孔病危害对李树不同病情等级叶片的蛋白质含量产生了极显著影响,各等级叶片的蛋白质含量出现变化,有升有降,但最终还是不能抵抗病害的胁迫,4级叶片的含量最低且显著区别于其他各级叶片;细菌性穿孔病危害对李树叶片的氨基酸种类无影响,均有必需氨基酸9种和非必需氨基酸8种,但绝大多数种类氨基酸含量通常随叶片病情等级的提高而呈现不同幅度的下降,只有极少数种类出现小幅度的提升,两者紧密关联。研究可为从生理生化角度探讨李细菌性穿孔病的致病机理提供基础数据。     

Epiphytic growth of Xanthomonas arboricola and Xanthomonas citri on non‐host plants

The population dynamics of Xanthomonas arboricola pv. pruni (Xap) and X. citri subsp. citri (Xcc) was assessed on over three dozen plant species/genotypes under field and greenhouse conditions. Both Xap and Xcc multiplied on red nightshade, black nightshade, bindweed, Chenopodium, common bean and wheat up to 20 days post‐inoculation (dpi) under greenhouse conditions. A high bacterial growth rate was observed on all (alfalfa, bindweed, Chenopodium, field mustard, millet and prickly lettuce) but one (liquorice) plant species tested under field conditions. Xap successfully proliferated on both lemon and sweet lemon up to 140 dpi, attaining a population density even higher than that of Xcc. The latter showed an increased growth rate on GxN, GF677, Ghisella 6 and Mariana 2624 rootstocks up to 140 dpi. While Xap and Xcc did not grow on pomegranate and common fig, they had a steady population growth on apple and pear plants up to 140 dpi, although the final population sizes were smaller than those observed on lemon and sweet lemon plants. The results suggest that a large number of non‐host plant species could support epiphytic populations of Xap or Xcc, which may have implications for plant disease epidemiology.     

Evaluation of seedborne bacterial pathogens on common bean cultivars grown in central Anatolia region,Turkey

Bacterial diseases of bean cause economically important losses worldwide. The most important method for managing bacterial diseases on bean is the use of pathogen-free seed. In this study, 198 different dry bean seed samples of six different cultivars including Dermason, Cali, Sira, Battal, Bombay and Seker, were collected from 12 provinces of Central Anatolia Region of Turkey. All were tested to investigate the seedlots as primary inoculum sources of the major bacterial diseases. The data revealed that 22,72 %, 13,63 %, 11,11 %, 1,51 % and 0.5 % of seed samples tested were contaminated with five seedborne bacterial pathogens, Pseudomonas savastanoi pv. phaseolicola (Psp), Pseudomonas syringae pv. syringae (Pss), Xanthomonas axonopodis pv. phaseoli (Xap), X. axonopodis pv. phaseoli var. fuscans (Xapf) and Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), respectively. All bacterial strains isolated were identified based on morphological, physiological, biochemical, molecular and pathogenicity tests. The results showed that Psp and Pss were found together on cv. Cali; Psp and Xap on cv. Dermason and cv. Sira; and Pss and Xap on cv. Seker, cv. Dermason, and cv. Cali. Therefore, the results in the present study suggested that evaluation and selection of pathogen-free seeds are very important for preventing the spread of pathogens and effective management of seed borne bacterial diseases prevalent in bean growing regions; in addition to implementation of integrated crop production strategies such as crop rotation, sanitation, seed treatment, tolerant/resistant cultivar selection and proper bactericide application.     

一串红穿孔病病原鉴定和初侵染源分析

 2021年夏季,受台风“烟花”影响,上海市奉贤区海湾镇大面积一串红种苗突发穿孔病,本文按照柯赫氏法则鉴定病原物并进行初侵染源分析。从田间病样中分离出的黄色分离物YchA回接一串红形成穿孔症状,在非寄主本氏烟草上可激发过敏反应。16S rDNA序列分析显示YchA为黄单胞菌属;以持家基因fyuA、gyrB、rpoD进行多位点序列分析(Multi-locus sequence analysis, MLSA)发现,菌株YchA与核桃细菌性黑斑病菌(Xanthomonas arboricola pv. juglandis, Xaj)亲缘关系最近;Biolog鉴定系统分析显示,一串红穿孔病病原为Xaj的可能性约为68%。对育苗基质、种子和灌溉水的检测发现,种子和灌溉水带菌。这些结果表明,一串红细菌性穿孔病的病原为树生黄单胞菌(X. arboricola),可能是一个新致病变种;种子带菌是病害的初侵染来源,灌溉水带菌扩散。     

Critical disease components of common bacterial blight to effectively evaluate resistant genotypes of snap bean

Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli (Xap) is the main bacterial disease of snap bean. The present work aimed to select snap bean genotypes that are resistant to CBB based on three components of resistance: area under the disease progress curve, latent period, and lesion diameter on pods (DL). A completely randomized two-factor factorial design with six replications was used to evaluate leaves and pods of 14 snap bean and three common bean genotypes (PI 207262, BAC-6 and A-794) with high resistance to CBB. Two Xap isolates, 1394-98 and 775-90, were used to inoculate leaves and pods. Data were analyzed using nonparametric statistics. Significant differences were observed among the evaluated genotypes for all of the components of resistance, except for DL. The snap bean UENF 1482 demonstrated good performance in two disease resistance components. For this reason, this genotype can be recommended for use in breeding programs that aim to generate snap bean genotypes resistant to Xanthomonas axonopodis pv. phaseoli.     

李果实细菌性穿孔病发生规律及防治

在辽宁省多数李树品种的果实上发生细菌性穿孔病,病斑近圆形、暗紫色、边缘具水渍状晕环,使果实去失商品价值。研究结果发现果实自落花后１５ｄ至采收前都可被侵染;雨日多、雨量大、品种感病、树势旺盛为病害流行的因素;防治该病有效措施是栽植抗病品种,消灭初侵染源,加强栽培管理,生长期用药控制病害发生。     

Comparison of extraction procedures for detection of Xanthomonas axonopodis pv. phaseoli in common bean seed

Xanthomonas axonopodis pv. phaseoli (Xap) is an important seedborne pathogen of Phaseolus vulgaris. Accurate seed health testing methods are critical to protect seed quality and meet phytosanitary requirements. Currently employed selective media‐based methods include several variations in extraction procedures. In order to optimize pathogen extraction from seeds, the influence of different extraction steps on the sensitivity of Xap detection was assessed. Seeds were inoculated by vacuum infiltration with Xap to achieve inoculum levels from 10¹ to 10⁵ CFU per seed; one contaminated seed was mixed into 1000‐seed subsamples of uncontaminated P. vulgaris seeds. Thirty subsamples of 1000 seeds were tested using each different extraction procedure. These included soaking whole seeds in sterilized saline phosphate buffer, either overnight at 4°C or for 3 h at room temperature, with or without vacuum extraction, and either with or without concentrating the seed extract by centrifuging. Seed extract dilutions were cultured on semiselective agar media MT and XCP1. The percentages of positive subsamples were compared to measure the effects of each extraction step on detection sensitivity. Vacuum extraction and centrifugation of seed extracts increased sensitivity; the highest sensitivity was obtained with the 3 h vacuum extraction followed by centrifugation. These results were confirmed with naturally infested seeds; Xap was detected in 48 of 70 samples using the 3 h vacuum extraction with centrifugation, whereas only 35 of 70 field samples tested positive using overnight soaking, a significant difference. The results suggest that these steps would be valuable modifications to the current method approved by the International Seed Testing Association (ISTA).     

Influence of Ring Nematode Infestation and Calcium, Nitrogen, and Indoleacetic Acid Applications on Peach Susceptibility to Pseudomonas syringae pv. syringae

ABSTRACT Two field experiments were conducted to study the effects of added nitrogen, calcium, and indoleacetic acid, in the presence or absence of ring nematodes (Mesocriconema xenoplax), on susceptibility of peach to bacterial canker. When noninfested soil was inoculated with ring nematodes, peach tree susceptibility to bacterial canker infection caused by Pseudomonas syringae pv. syringae was dramatically increased after a period of 2 years. However, no evidence was found that ring nematode infestation increased tree water stress or, in turn, altered plant calcium uptake. Soil fumigation with methyl bromide prior to planting in a commercial orchard significantly reduced both nematode populations and peach tree susceptibility to bacterial canker infection when compared with nonfumigated treatments. In both experiments, tree susceptibility, as measured by canker length following inoculation of stems with P. syringae pv. syringae, was negatively correlated with plant tissue nitrogen content and positively correlated with tissue calcium content. A principal components analysis showed that tissue nitrogen and calcium levels were negatively correlated, and that high-nitrogen, low-calcium tissues were less susceptible to bacterial canker than low-nitrogen, high-calcium tissues. These results indicate that the increased susceptibility of peach to P. syringae pv. syringae under nematode infestation conditions is mediated by both nutritional effects (primarily nitrogen) and nutritional-independent effects, but do not support previous reports of beneficial effects of calcium for reducing bacterial canker.