江西柑橘主产区柑橘衰退病毒分离株组群分析

为检测江西柑橘主产区柑橘衰退病毒分离株组群的构成情况,运用限制性片段长度多态性(RFLP)对收集自江西柑橘14个主产区果园的CTV分离株进行分析。发现209份样品的CP/HinfⅠ酶切结果中182份样品表现出单一CP/HinfⅠRFLP谱型,占鉴定样品总数的87.1%,其中以CP/HinfⅠRFLP第3和第1组群的分离株构成为主,分别占样品总数的55.5%和26.8%;混合CP/HinfⅠRFLP组群样品占12.9%。本次检测中发现有1个分离株为第4组群,5个分离株为第5组群,可能为潜在的弱毒分离株。本次试验中检测的江西柑橘样品以CTV单一组群感染为主。     

6种柑橘类植物对柑橘衰退病毒分离株TR-L514变异的影响

 柑橘衰退病毒(Citrus tristeza virus,CTV)存在复杂的株系分化现象,运用弱毒株交叉保护防治柑橘衰退病时需了解不同类型柑橘对CTV构成的影响。作者将CTV分离株TR-L514嫁接接种到6类柑橘植物上获得了18个亚分离株,并对这18个亚分离株和TR-L514进行了指示植物鉴定,p25基因的限制性片段长度多态性(RFLP)和单链构象多态性(SSCP)分析,p23基因的序列比较。结果表明,CTV株系对不同柑橘类植株的适应性存在差异。TR-L514嫁接到不同柑橘类植株其构成会发生变化,在甜橙上可以同时检测出p25//HinfⅠ RFLP第1和6组群,并具有比在其它4类柑橘上更为复杂的SSCP谱型构成,因此甜橙可能更适宜于CTV的增殖。TR-L514及18个亚分离株的p23基因序列差异可能与不同类柑橘植株的适应性有关。     

4种柑橘衰退病毒源单蚜传毒分离株CP基因的分子特征

 对4种柑橘衰退病毒源及其31个单蚜传毒分离株的CP基因做了限制性片段长度多态性(RFLP)和单链构象多态性(SSCP)分析,并对其中8个单蚜传毒分离株的CP基因进行了序列分析。实验明确了所研究柑橘衰退病毒(Citrus tristeza virus,CTV)的CPG/Hinf I RFLP组群和CPG/SSCP模式,二者能较好地对应并有效验证了单蚜传毒对CTV毒源的分离纯化作用;CP基因序列分析结果表明,相同CPG/Hinf I RFLP组群的单蚜传毒分离株间具有高度的序列相似性,而不同CPG/Hinf I RFLP组群单蚜传毒分离株间则存在较大差异;通过与已知生物学特性CTV分离株比较,初步建立了上述CP基因分子特征与病毒生物学特性之间的联系。     

毒源和寄主对褐色桔蚜传播柑桔衰退病毒效率的影响

褐色桔蚜是柑桔衰退病毒(Citrus tristeza virus,CTV)最有效的传播媒介,为了解不同柑桔寄主种类和毒源对褐色桔蚜传播CTV效率的影响,检测在以锦橙、凤凰柚和墨西哥来檬作毒源植株时,褐色桔蚜对10个CTV分离株的单蚜传毒率,以及蚜传前后CTV分离株p25/HinfⅠRFLP组群构成的变化,并对其中5个分离株与2个国外分离株进行了p20和p25基因相应氨基酸序列的比对分析。结果表明:褐色桔蚜传播CTV的能力受柑桔寄主种类的影响较大,以锦橙作毒源植株可以获得最高的传毒率;CTV毒株强弱以及褐色桔蚜虫态(有翅或无翅蚜)对单蚜传毒率影响不明显;褐色桔蚜传播具有p25/HinfⅠRFLP第3组群构成的CTV分离株的能力较强。     

柑橘衰退病毒柚分离株的p25/Hinf1 RFLP分析

对123个柑橘衰退病毒柚分离株进行p25/Hinf1 RFLP分析明确:样品中,单一p25/Hinf1 RFLP组群样品占样品总量的82.9%,说明我国田间受侵染柚类中柑橘衰退病毒株系相对较为单一;RFLP组群6的样品占样品总量的79.7%,说明目前柚类生产上的优势流行株属于p25/Hinf1 RFLP组群6,初步认定为强毒株系;柑橘衰退病毒株柚分离株S102、S104、S106、S108属于p25/Hinf1 RFLP组群5,初步认定是弱毒株系。     

广西柑橘衰退病和黄脉病调查及其病原病毒的遗传多样性分析

为明确柑橘衰退病毒(citrus tristeza virus, CTV)和柑橘黄脉病毒(citrus yellow vein clearing virus, CYVCV)在广西柑橘上的发生?分布及其遗传变异情况, 于2020年至2021年对百色?北海?崇左?贵港?桂林?河池?贺州?来宾?柳州?南宁?梧州和玉林等12个柑橘产区进行了病毒病调查?采用RT-PCR对采集样品进行了病毒检测, 并基于病毒分离物外壳蛋白(coat protein, CP)基因的核苷酸序列进行比对分析, 构建系统发育树?结果表明:采集的737份柑橘样品中, CTV的检出率为20.62%, CYVCV检出率为18.32%, CTV的检出率略高于CYVCV?病毒复合侵染的现象在采集的柑橘样品中普遍存在, CTV和CYVCV复合侵染率高达34.50%?对RT-PCR产物测序共获得12个CTV分离物和6个CYVCV分离物的CP基因序列?遗传多样性分析发现, CTV和CYVCV的CP基因序列都较保守, CTV分离物的遗传进化与地理来源?寄主来源均没有明显相关性, 但CYVCV分离物的遗传进化与地理位置具有相关性, 而与寄主来源无明显相关性?上述研究结果可为深入了解CTV和CYVCV在广西的流行情况以及柑橘病毒病的检疫和防控提供参考?     

重庆地区柑桔衰退病毒多态性研究

柑桔衰退病毒(CTV)存在着复杂的株系分化现象.在使用弱毒株交叉保护防治柑桔衰退病时需要对田间病毒株系组成进行分析,并对选用的株系进行单蚜分离纯化.作者运用限制性片段长度多态性和单链构象多态性对田间获得的168个CTV样品和2个蚜传毒株的外壳蛋白基因进行分析,了解重庆市田间CTV组群构成情况,发现田间CTV以多株系混合发生为主,其中主要是CP/HinfⅠRFLP第1、3和6组群,约占总数的90%,并以强毒株混合感染为主.甜橙中CP/HinfⅠRFLP的组群构成最为复杂.单头褐色桔蚜从柚类至甜橙传播CTV的效率低(不足1%),该蚜的取食可改变CTV的株系组成.     

宜都市果断处置柑橘溃疡病疫情

<正>2017年7月17日,宜都市高坝洲镇大战坡村二组部分农户反映,个别桔园发现有疑似柑桔溃疡病典型症状病树。接到报告后,宜都市植物检疫部门第一时间到达现场,并进行了现场初步确认。经及时送样湖北省植物保护总站植物检疫科专家鉴定,确诊为柑桔溃疡病。发现疫情后,我们进一步核查摸底,确定有典型症状的6户约0.5hm2689株病株,品种为纽荷尔脐橙、柚树和夹杂的少量温州蜜柑,典型症状农户周边需     

脐橙优质高产栽培和病虫害防治技术

泉州市从1997年开始,陆续引进一些脐橙品种,经过观察、鉴定,筛选出适宜本地栽培的纽荷尔脐橙等优良品种。到2004年底,全市脐橙种植面积达321hm2,主要分布在南安、永春、德化等县(区、市),栽培经济效益比较明显,充分调动了果农种植的积极性,为泉州市柑橘品种结构调整提供示范作用。脐橙适宜栽培区年平均气温18.5℃以上,≥10℃年有效积温为6000～7000℃,年平均降雨量l000～1700mm,极端     

两类抗生素药剂对‘纽荷尔’脐橙黄龙病菌的抑制作用及根际细菌群落结构的影响

为探究磺胺二甲氧嘧啶钠盐（sulfadimethoxine sodium salt, SDM）和氨苄青霉素（ampicillin, AMP）对柑橘黄龙病（citrus Huanglongbing, HLB）的防效以及对柑橘根际细菌群落结构的影响, 本试验以‘纽荷尔’脐橙为研究对象, 采用0.5 g/L SDM和1 g/L AMP进行灌根, 使用TaqMan qPCR技术监测病树叶内黄龙病菌菌量的动态变化, 并利用宏基因组技术分析根际细菌群落结构的变化。结果显示, AMP连续处理后病树叶片内黄龙病菌菌含量在一定程度上受到抑制, 初步判断AMP对黄龙病有一定的抑制效果, SDM处理对黄龙病菌菌含量抑制效果较差;2类抗生素处理组中根际主要优势类群结构和相对丰度在门、属分类水平上均发生改变, 解磷细菌中慢生根瘤菌属Bradyrhizobium细菌的相对丰度在处理后有明显变化, pstA、pstC等部分磷循环功能基因相对丰度发生改变, 表明2类抗生素药剂均影响了‘纽荷尔’脐橙病树根际细菌群落结构。     

Characterisation of the fungal population in citrus packing houses

The aim of this work was the characterisation of the environmental and superficial mycoflora of equipment and facilities of two citrus packing houses in Sao Paulo State, Brazil, in 2004 and 2005. One of the packing houses packed fruit for the export market (municipality of Matao), the other for the domestic market (municipality of Engenheiro Coelho). The study also identified the presence of isolates of Penicillium spp. resistant to thiabendazole and imazalil fungicides in packing houses. The environmental mycoflora was sampled according to the gravimetric method, using Petri dishes containing potato dextrose agar medium opened for 2 min. The superficial mycoflora on equipment and facilities was sampled with Rodac plates. The mycoflora in the environment and on surfaces of the packing houses in Matao were 12.3 and 52.3 cfu/plate, respectively, while these populations for the Engenheiro Coelho packing house were 46.3 and 68.2 cfu/plate, respectively. Cladosporium and Penicillium were the most prevalent genera of fungi. The contamination levels of clean zones in the packing houses (washing of fruits, packing table, boxes and containers) was not substantially lower than the contamination in dirty zones (reception of fruits and first selection). The percentage of P. digitatum isolates in Matao that was resistant to thiabendazole and imazalil was 25.9 and 1.5 in the environment and 30.1 and 16.0 on packing house surfaces, respectively. In Engenheiro Coelho, percentage of resistance to these fungicides was 51.9 and 0.1 in the environment and 39.2 and 0.9 on packing house surfaces, respectively.     

土霉素对柑橘黄龙病的防治效果及对柑橘产量和品质的影响

为有效防控柑橘黄龙病，于2017年在佛罗里达大学柑橘研究与教育中心的奥本代尔市柑橘试验场进行田间试验筛选黄龙病的防治药剂及其浓度，测定注射土霉素后叶片中柑橘黄龙病菌亚洲种Cadidatus Liberibacter asiaticus、土霉素、淀粉含量、柑橘产量、出汁率、可溶性固形物含量和酸度，显微镜下观察注射土霉素后淀粉粒的分布。结果表明，浓度为1.6g/株土霉素处理180 d后柑橘叶片中黄龙病菌亚洲种含量减少幅度最大，为91.78%；注射浓度为1.6g/株土霉素后7d，叶片中土霉素含量达142.2 μg/kg，注射后11 d叶片中土霉素含量达到最大，为239.8 μg/kg，注射后45 d叶片中土霉素含量低至99.6 μg/kg以下；注射后7~90d，叶片中黄龙病菌亚洲种含量呈波浪形变化，注射90 d后叶片中黄龙病菌亚洲种含量一直处于增长趋势，叶片中黄龙病菌亚洲种含量总体随着土霉素含量的升高而降低；注射浓度为1.6g/株土霉素后，叶片中淀粉含量大幅度下降，60d时达到最低值，为3.3 μg/mm²，90d时达到峰值，为14.5 μg/mm²；单株产量为16.7 kg，与注射浓度为0.8 g/株土霉素处理差异不显著，但均显著高于其它2个处理；柑橘出汁率、可溶性固形物和酸度均与清水对照差异不显著。表明土霉素可有效抑制黄龙病菌亚洲种，减少柑橘叶片内淀粉含量，增加柑橘产量，但对果实品质未产生显著影响。     

Differentiation of citrus bacterial canker strains in Korea by host range,rep-PCR fingerprinting and 16S rDNA analysis

Soil-borne cereal mosaic virus (SBCMV) causes a severe disease in susceptible cultivars of winter wheat. The virus is vectored by the soil-borne protist Polymyxa graminis. Experiments were conducted to investigate whether SBCMV RNA2 could persist in seed from SBCMV-infected susceptible cultivars of winter wheat. Over 7,000 seedlings were generated from seed collected from two cultivars of SBCMV-infected winter wheat. Seedlings were grown in a glasshouse compartment and batch tested for the presence of SBCMV using real-time RT-PCR. The majority of batches tested positive for SBCMV, indicating an RNA2 transmission rate of 1.8–9.4% in wheat. The presence of the virus was confirmed by amplifying and sequencing a larger (400 bp) fragment of viral RNA2 in a sub-set of the seedlings testing positive by real-time RT-PCR. Root extracts from this sub-set tested negative for P. graminis using real-time PCR. The implications for disease epidemiology of this virus are discussed. The authors are British Civil Servants and as such their work is subject to British Crown Copyright. This means the exclusive copyright for the article cannot be transferred.     

福建省柑橘褐斑病菌的分离、鉴定和系统进化分析

为明确在福建省南平市的橘柚和三明市的温州蜜橘上发现的疑似柑橘褐斑病的病原菌种类,采用组织分离法获得纯化菌株,通过回接法验证菌株的致病性,利用形态学特征对病原菌进行初步鉴定,并采用最大似然法以多聚半乳糖醛酸酶基因endoPG为靶标对本研究以及国内外已报道的链格孢菌株构建系统发育树,分析其遗传多样性。结果表明,从病组织中共分离获得26株纯培养菌株,经形态学鉴定均为链格孢菌Alternaria spp.。利用分生孢子液接种橘柚离体嫩叶发现,有22株菌株能侵染橘柚叶片并产生与田间相似的褐斑病症状,确认该病害为链格孢引起的柑橘褐斑病。系统发育树分析结果显示,分离所得的26株菌株均聚在已报道的4个柑橘链格孢进化分支Clade1～Clade4中,其中21株菌株聚在国内特有的分支Clade4中,有3株菌株和1株菌株分别聚在国内外兼有的分支Clade3和Clade1中,1株菌株聚在国外特有的分支Clade2中,表明在福建省采集的这些柑橘褐斑病菌均为链格孢菌,且遗传多样性较丰富。     

Fenpropimorph: a promising fungicide for postharvest diseases in citrus fruits

Sour rot, green mold and blue mold are postharvest diseases of citrus fruit. Benzimidazole and imidazole fungicides control molds, and guazatine controls sour rot, but strains ofPenicillium spp. resistant to these chemicals have been reported. Aqueous formulations of fenpropimorph, a morpholine fungicide, are very active in controlling fungi attacking postharvest citrus fruits. The fungicidal effect of the chemical in the coating wax was investigated in combined treatments with guazatine in dip or spray applications on various citrus fruit varieties. Fenpropimorph alone was as good as or a better curative and protective treatment than the current commercial treatments applied in packinghouses in Israel for decay control.     

A new method for inoculation of fruit with <Emphasis Type="Italic">Guignardia citricarpa</Emphasis>, the causal agent of citrus black spot

Citrus black spot (CBS) is a fungal disease, caused by Guignardia citricarpa, that has a high economic impact on citrus. Although G. citricarpa has been associated with black spot of citrus, an adequate pathogenicity test is still not available. Thus, our objective was to develop and evaluate a simple, safe, and practical pathogenicity test. We used fruits from Pera-Rio and Valencia sweet orange trees from two different orchards, located in the State of São Paulo, Brazil. Inoculation was performed by placing six disks colonized by G. citricarpa, onto the peel of healthy fruits, previously bagged. In the Pera-Rio sweet orange grove, initial symptoms of the false melanose type resulting from the inoculations were observed 55 days after inoculation (dai). In the Valencia grove, initial symptoms also of the false melanose type resulting from the inoculations occurred 73 dai. A total of 92.8% and 86.6% of the Pera Rio and Valencia fruits inoculated, respectively, showed symptoms of CBS. Citrus black spot symptoms were not observed in any of the control fruits.     

LncRNA在柑橘木虱与黄龙病病原菌互作中的差异表达分析及验证

为明确柑橘黄龙病的唯一自然传播媒介——柑橘木虱Diaphorina citri的长链非编码RNA(long non-coding RNA,lncRNA)是否参与调控黄龙病病原菌Candidatus Liberibacter asiaticus(CLas)的侵染及复制,采用生物信息学预测及PCR扩增方法进行lncRNA的预测、特征分析、验证及差异表达分析。结果显示,柑橘木虱的13个转录组RNA-Seq数据中共有10 192个lncRNA基因,对应15 747条lncRNA转录本;与蛋白质编码基因相比,柑橘木虱lncRNA具有更少的外显子数量和更短的转录本长度;随机选取的10条lncRNA基因中,有7条lncRNA基因在无菌柑橘木虱广州品系或赣州品系中有表达,其中1条lncRNA基因TCONS_00034665在无菌广州品系和无菌赣州品系中存在差异表达;带菌和无菌柑橘木虱成虫中预测获得2个差异表达的lncRNA基因TCONS_00096118和TCONS_00234564,实时荧光定量PCR验证发现TCONS_00234564与预测结果一致,在带菌柑橘木虱成虫中高表达。表明lncRNA参与了黄龙病病原菌与寄主柑橘木虱的互作。     

Modelling the progress of Asiatic citrus canker on Tahiti lime in relation to temperature and leaf wetness

The combined effect of temperature (15°C, 20°C, 25°C, 30°C, 35°C, 40°C and 42°C) and leaf wetness duration (0, 4, 8 12, 16, 20 and 24 h) on infection and development of Asiatic citrus canker (Xanthomonas citri subsp. citri) on Tahiti lime plant was examined in growth chambers. No disease developed at 42°C and zero hours of leaf wetness. Periods of leaf wetness as short as 4 h were sufficient for citrus canker infection. However, a longer leaf duration wetness (24 h) did not result in much increase in the incidence of citrus canker, but led to twice the number of lesions and four times the disease severity. Temperature was the greatest factor influencing disease development. At optimum temperatures (25–35°C), there was 100% disease incidence. Maximum disease development was observed at 30–35°C, with up to a 12-fold increase in lesion density, a 10-fold increase in lesion size and a 60-fold increase in disease severity.     

基于DNA条形码技术的湖南省柑橘主产区实蝇幼虫分子鉴定

为明确湖南省柑橘主产区的实蝇入侵为害现状,从该省7个市(自治州)22个地点收集柑橘蛆果中的幼虫,利用DNA条形码技术对其进行分子鉴定,并以DNA条形码序列作为分子标记探究橘大实蝇Bactrocera minax的20个中国地理种群(湖南省6个组群共16个种群、其它3省市4个种群)以及1个印度地理种群间的亲缘地理关系,分析橘大实蝇在我国的遗传进化关系。结果表明,仅采集自邵阳市城步苗族自治县柑橘蛆果中的5头幼虫被鉴定为蜜柑大实蝇B. tsuneonis,其余21个地点采集的595头幼虫均被鉴定为橘大实蝇。21个橘大实蝇地理种群的平均单倍型多样性为0.75,核苷酸多样性为0.0032,核苷酸差异数为2.13,中国所有地理种群均具有较高的遗传多样性;单倍型网络进化图显示湖南、重庆、贵州种群共享的单倍型H3为原始单倍型,表明其为比较原始的种群;AMOVA分析结果显示种群内个体间遗传变异占总体变异的59.04%,是遗传变异的主要来源;遗传分化结果表明湖南省6个组群间均出现了中度至高度的遗传分化,FST在0.0521～0.7795之间。表明DNA条形码技术可用于蜜柑大实蝇和橘大实蝇幼虫的分子鉴定及其种群遗传进化分析。     

龟纹瓢虫对柑橘木虱的捕食功能反应及猎物偏好性

为评估龟纹瓢虫Propylea japonica对柑橘木虱Diaphorina citri的生物防治潜能，在实验室条件下测定龟纹瓢虫1~4龄幼虫和成虫对柑橘木虱5龄若虫的捕食功能反应、搜寻效应、自身密度干扰反应以及捕食偏好性。结果表明，龟纹瓢虫1~4龄幼虫和成虫对柑橘木虱5龄若虫的捕食功能反应均符合Holling II型功能反应类型，其各虫态龟纹瓢虫的瞬时攻击率分别为0.313、0.610、0.234、0.585和0.675，处理时间分别为0.088、0.077、0.013、0.008和0.016 d，龟纹瓢虫4龄幼虫对柑橘木虱5龄若虫的捕食能力最大，为73.125，龟纹瓢虫成虫、3龄幼虫、2龄幼虫、1龄幼虫次之，捕食能力分别为42.188、18.000、7.922和3.557。各虫态龟纹瓢虫对柑橘木虱5龄若虫的搜寻效应随柑橘木虱5龄若虫密度升高而下降；在柑橘木虱5龄若虫密度一定的条件下，各虫态龟纹瓢虫对柑橘木虱5龄若虫的捕食率随自身密度升高而下降，其自身密度干扰方程为E=0.421P^-0.52；当柑橘木虱5龄若虫和豆蚜Aphis craccivora 4龄若虫2种猎物共存时，龟纹瓢虫成虫对其食物选择性指数均小于1，表明龟纹瓢虫成虫对这2种猎物无捕食偏好性。表明龟纹瓢虫对柑橘木虱5龄若虫有较强的防控潜能。