广西局地西番莲病毒病的病原鉴定及优势病毒分析

 在广西采集表现斑驳、花叶症状疑似病毒病的西番莲叶片样品,利用小RNA测序技术,结合生物信息学分析,鉴定侵染西番莲的病毒种类。参考测序结果采用DAS-ELISA和RT-PCR方法对2015~2018年间采集的385份疑似病毒病样品进行检测,分析引发广西西番莲病毒病的优势病毒种类。结果显示:小RNA共获得20 921 061 clean reads,拼接获得560个contigs,其中99个contigs被注释为夜来香花叶病毒(telosma mosaic virus,TeMV),97个contigs被注释为黄瓜花叶病毒(cucumber mosaic virus,CMV),69个contigs被注释为东亚西番莲病毒(East Asian passiflora virus,EAPV),12个contigs被注释为大豆花叶病毒(soybean mosaic virus,SMV)。提取送测序的同批样品叶片的总RNA进行RT-PCR验证,可检测出TeMV、EAPV和CMV 3种病毒,未检出SMV。采用DAS-ELISA和RT-PCR对采集的样品进行检测,结果发现284份样品为阳性样品,检出率为73.76%,其中TeMV的检出率最高为64.16%,其次为EAPV和CMV,检出率分别为41.30%和11.43%;3种病毒存在复合侵染现象,其中TeMV+EAPV的检出率最高为24.94%,TeMV+CMV的检出率为4.16%,EAPV+CMV的检出率为0.26%,3种病毒复合侵染的检出率为4.94%。     

环斑花叶病侵染对番木瓜叶片叶绿素含量和光合羧化酶活性的影响

 番木瓜(Carica papaya)叶子罹致环斑花叶病,引起叶绿素和蛋白质含量的降低。罹病叶片的叶绿素和蛋白质含量分别为健叶的79.7%和58.3%。罹病叶片的RUBP羧化酶和PEP羧化酶活性分别为健叶的37.2%和53.2%。RUBP羧化酶与PEP羧化酶活性比从健叶的7.22降至5.01。环斑花叶病侵染对RUBP羧化酶活性的影响较PEP羧化酶大。罹病叶子的苹果酸酶和苹果酸脱氢酶活性亦较健叶的低,分别为健叶的68.5%和44.8%。环斑花叶病侵染可能引起叶子光吸收和二氧化碳羧化能力的降低,从而影响植株的生长和果实的产量。     

西番莲中夜来香花叶病毒实时荧光定量PCR检测方法的建立及应用

夜来香花叶病毒(telosma mosaic virus, TeMV)是对西番莲危害较大的一种病毒病原。根据病毒末端结合蛋白(VPg)序列设计引物, 建立了以Vpg-334F/506R为特异性引物, 退火温度54℃, 引物浓度0.6 μmol/L的SYBR Green Ⅰ实时荧光定量PCR检测方法。该方法可特异性扩增TeMV基因组6 483~6 675 nt区域, 所得标准曲线扩增效率为102.77%, 决定系数为0.996 1, 最低检测浓度为2.370×10 2 拷贝/μL, 灵敏度是普通PCR的1 000倍。应用该方法对接种TeMV的西番莲进行检测, 发现接种3 d后可在叶片中检测到TeMV, 定量分析不同温度下TeMV在叶片中的积累, 发现26~28℃下病毒积累速度最快, 且植株症状表现与病毒积累量密切相关。对赣南地区采集的76份西番莲田间样品进行检测, 共检出71份阳性样品, 检出率为93.4%。综上, 本研究建立的实时荧光定量PCR方法特异性强, 灵敏度高, 适于TeMV的快速检测。     

串珠镰刀菌引起玉米穗粒腐病防御酶变化及其电镜观察

 对串珠镰刀菌(Fusarium moniliforme)侵染引起玉米穗粒腐病的防御酶活性变化和病原菌侵染过程进行研究。采用人工接菌的方法,分别对抗(Bt鄄1)、感(掖478)玉米材料进行接种,取抗、感材料间隔24 h 的6 个时间段接菌部位的苞叶组织,分析玉米植株感病后部分防御酶、同工酶谱的动态变化,并用扫描电镜对病原菌入侵植株过程进行组织病理学观察。扫描电镜观察发现,菌丝首先要经过1 ~ 3 d 生长后,大约在72 h 左右开始侵入气孔,并且随着时间的推移,侵入气孔的菌丝量逐渐增多。这说明病原菌是直接通过气孔侵入寄主苞叶组织。同时,玉米受串珠镰刀菌侵染后,苯丙氨酸解氨酶 (PAL)和过氧化物酶(POD)的活性都是先上升后下降,在感病材料Ye478 中PAL 的活性要比抗病材料Bt鄄1 中增加的更快、更高;同样对于POD 来说,在感病材料Ye478 中的活性要比抗病材料Bt鄄1 中的高,但变化趋势在2 个材料中相似;而丙二醛(MDA)的含量则相反,在感病材料Ye478 中的活性要比抗病材料Bt鄄1 中的低;对POD 同工酶酶谱分析,2 个材料都增加了3 ~ 4 个条带,没有明显的区别,这说明玉米感病后会通过增加POD 的活性来抵御外源病菌的侵入。总体而言PAL和POD 活性水平与材料抗性呈负相关;MDA 与材料抗性呈正相关关系。对玉米植株感病后防御酶活性变化的分析和病原菌入侵寄主的电镜观察结果,可为深入研究玉米穗粒腐病抗病机制和抗病育种提供参考。     

猕猴桃品种对细菌性溃疡病的抗性机制

研究了安徽省猕猴桃主栽品种金魁(高抗)、早鲜(中抗)、魁蜜(抗病)、华美2号(感病)、秦美(中感)和金丰(高感)对细菌性溃疡病的抗性机制.结果表明:形态结构抗性方面,感病品种的皮孔密度和长度及气孔密度、长度和宽度都明显高于抗病品种,抗、感品种间皮孔、气孔的排列方式也存在一定差异.相关分析表明,皮孔密度和长度及气孔密度、长度和宽度与品种发病率都有较高的相关性,尤其以皮孔长度和气孔长度相关性最高,r分别为0.9278和0.9794;生理生化抗性方面,品种未感染溃疡病菌前,芽中的POD酶活性与品种抗性存在规律性不强,一年生枝条、叶片中的POD酶活性与品种抗性有密切关系.品种感染溃疡病菌后,POD酶活性均升高,但抗病品种中酶活提高倍数高于感病品种.一年生枝条上病斑越大,POD酶活性越高.POD同工酶谱带表现出与酶活相一致的规律.     

玉米灰斑病抗性机制中活性氧代谢的作用

研究了玉米灰斑病菌侵染四个抗病和感病的玉米品种时，叶片内部活性氧代谢酶及细胞过氧化产物含量的动力学变化。结果表明，抗、感病品种的SOD、CAT及POD酶活性在病茵侵染后都变化显著，抗病品种各酶活性变化幅度比感病品种大。叶片内过氧化产物MDA含量则相反，抗病品种沈试29在接种第13天时叶片MDA含量只为18．46nmol／g，而感病品种铁单9为23．14nmol／g，抗病品种比感病品种增加幅度小。说明活性氧代谢在植物抗病机制中起着重要作用，抗病品种对活性氧代谢的酶调节能力强，病菌侵染后细胞过氧化程度低，在痛菌侵染时活性氧清除酶活性最大增加值与发病程度呈显著正相关。     

抗黑星病芽变鸭梨组织结构、生理生化与抗病性关系研究

对一株抗黑星病芽变‘鸭梨’的叶片组织结构和生理生化特性进行了研究,发现其叶片蜡质含量高、栅栏组织双层出现时间早、厚度大、海绵组织结构致密、气孔数目少,推断这些特性决定黑星病菌分生孢子不易侵入叶片内部;叶绿素含量高为植株抗病性提供了生理基础,可溶性糖含量低有可能抑制黑星病营养菌丝在细胞间的生长和扩展。通过研究该抗黑星病芽变‘鸭梨’的抗病机理,为‘鸭梨’抗黑星病育种提供了理论依据。     

不同叶龄鸭跖草对咪唑乙烟酸的耐药性

鸭跖草是黑龙江省大豆田危害严重的恶性杂草,而且其叶龄愈大愈难防除。作者通过盆栽试验及细胞显微技术研究不同叶龄鸭跖草对咪唑乙烟酸的耐药性差异及其与叶片显微结构的关系。结果显示,鸭跖草随着叶龄增大,对咪唑乙烟酸的耐药性增强,并在3叶龄时出现拐点;随着叶龄的增大,叶片表皮气孔密度显著下降;叶片厚度、叶片上下表皮厚度、栅栏组织及海绵组织厚度显著增大;10个栅栏组织细胞长度显著减小,栅栏组织排列由稀疏不规则向紧密规则的方向发展。以上变化是鸭跖草对咪唑乙烟酸耐药性增强的原因之一。     

香蕉苗纹枯病发病因素的测定

在香蕉离体叶上人工接菌表明,香蕉植株全生育期均可被丝核菌侵染,但以幼苗期最易感病。丝核菌侵染香蕉苗以25 ～30 ℃为适宜,高于35 ℃时失去致病能力。香蕉苗在全黑暗环境比在自然光下更感病。人工接种时,应用PDA 菌块比用病组织接种发病效果更好。     

斯里兰卡的胡椒小叶病

近年来在斯里兰卡的胡椒(Piper ni-grum)上发现有小叶病,田间发生率已达5—10％,成为斯里兰卡胡椒树上的一个突出病害。小叶病的主要症状是叶片褪绿,节间缩短,枝条增生,花苞变大并变绿。严重感病的植株叶片最后变黄,且叶组织硬化而易脆。在两个改良品种Panniyurl和Ku-ching的试验地里进行详细测量表明,在被侵染的藤子上其叶片的大小,每个穗上花的数目和浆果的重量均有减小。感病藤子上种     

福建西番莲病毒病的发生及其病原黄瓜花叶病毒亚组鉴定

1988～1995年对福建西番莲病毒病的发生为害进行调查,发现在西番莲栽培区病毒病普遍发生,发病率通常在30％～40％,严重的达90％以上。田间症状主要表现为叶片环斑、皱缩、花叶、环斑花叶,死顶和果实木质化等。从田间病株采集40份样本,经电镜观察和采用A蛋白夹心ELISA(PAS-ELISA),用西番莲木质化病毒(PWV)、西番莲黄花叶病毒(PFYMV)、紫果西番莲花叶病毒(GMV)、烟草花叶病毒(TMV)及黄瓜花叶病毒(CMV)的抗血清进行测定,其中36个样本检测出CMV,表明福建西番莲病毒病的主要病原为CMV。与此同时,对西番莲上CMV进行亚组鉴定,采用鉴别寄主和单、多克隆抗体双夹心ELISA(DAS-ELISA)对36个CMV阳性样本进行测定,结果35个属CMV亚组Ⅰ,1个属CMV亚组Ⅱ,表明田间以CMV亚组Ⅰ分离物占绝对优势。     

棉花受棉铃虫为害后的补偿效应及其数学模型研究

本文采用四因子二次正交旋转回归组合设计的试验结果,建立了以籽棉产量、皮棉产量、单株成铃及单株产量为目标函数,考虑种植密度、果枝数、模拟被害蕾(7月上旬)和被害幼铃(8月上旬)四决策变量的数学模型。模型行为反应表明:低密度(小于2千株/亩)或高果枝数(大于16个/株)条件下棉花补偿能力衰退;被害蕾量的增加在一定范围内有增产作用;被害幼铃的变化对产量的影响较大;但相对来说,密度和果枝数是影响产量的两个主要因素。模拟计算表明:允许蕾被害584—656个/百株和幼铃被害187—225个/百株,并配以密度4360—4520株/亩和果枝数14.4—15.06个/株的措施,可获取亩产皮棉95公斤以上。最后给出了不同农艺措施下棉花的损害函数。     

Ultrastructural study on acibenzolar-S-methyl-induced scab resistance in epidermal pectin layers of Japanese pear leaves

The infection behavior of Japanese pear scab pathogen Venturia nashicola race 1 was studied ultrastructurally in acibenzolar-S-methyl (ASM)-pretreated susceptible Japanese pear (cv. Kousui) leaves to determine the mechanism of ASM-induced scab resistance. On ASM-pretreated leaf surfaces, the infection behavior (conidial germination and appressorial formation) was similar to that on distilled water (DW)-pretreated leaves prior to cuticle penetration by the pathogen. However, after penetration, differentiated behavior was found in epidermal pectin layers and middle lamellae of the ASM-pretreated leaves. Subcuticular hyphae in epidermal pectin layers and middle lamellae of ASM-pretreated pear leaves were observed at lower frequency than in DW-treated leaves. The results indicated that fungal growth was suppressed in ASM-pretreated pear leaves. In the pectin layers of ASM- and DW-pretreated leaves, some hyphae showed morphological modifications, which were used as criteria to judge collapse of hyphal cells, including plasmolysis, necrotic cytoplasm, and cell wall destruction. More hyphae had collapsed in ASM-pretreated leaves than in DW-treated ones. In addition, the cell walls of collapsed hyphae broke into numerous fibrous and amorphous pieces, suggesting that ASM-induced scab resistance might be associated with cell-wall-degrading enzymes from pear plants. In addition, results from morphometrical analysis suggested that the activity or production of pectin-degrading enzyme from hyphae were inhibited by ASM application when compared with DW treatment.     

广西百香果采后果腐病病原的鉴定

0 引言 百香果(Passiflora edulis),学名西番莲,为西番莲科(Passifloraceae)西番莲属(Passiflora Linn.)草质藤本植物,原产于南美洲的巴西,在我国主要种植于热带、亚热带地区,具有极高的营养、保健和商品价值[1-2].目前,我国百香果的主栽品种为紫果百香果(Passiflo...     

Long-lasting systematic roguing for effective management of CABMV in passion flower orchards through maintenance of separated plants

In Brazil, passion flower is grown across almost the entire country. The predominant disease of the passion flower crop is passion fruit woodiness, caused by the potyvirus cowpea aphid-borne mosaic virus (CABMV), and transmitted by aphids in a nonpersistent manner. The disease reduces the useful life of the orchard from 36 months to approximately 18 months. Up to now, there has not been an efficient method for disease management. The aim of this work was to evaluate the efficiency of systematic roguing of diseased plants through weekly inspections, for disease management in the field. The latent and incubation periods of CABMV in passion flower vines were determined in order to optimize roguing efficiency. Passion fruit plants inoculated with CABMV started to act as sources of inoculum from 3 days after inoculation (DAI), and the symptoms were expressed, on average, at 8 DAI. Five field experiments, conducted in the states of São Paulo and Bahia, Brazil, demonstrated that systematic roguing of diseased plants was significantly efficient for managing passion fruit woodiness disease. In order to facilitate identification and subsequent removal of the infected plants, they need to be grown separately. This cultural practice can be recommended for managing passion fruit woodiness disease, provided it is applied on a regional scale by all passion fruit growers. The development of some pilot plantings for the application of roguing in a passion flower-producing region is recommended to validate the use of this technique for managing passion fruit woodiness disease.     

百香果疮痂病病原菌鉴定

To identify the pathogen causing scab disease on the fruit of Passiflora Linn. in the passion fruit yard of Cenxi and Nanning cities, Guangxi province. The scab tissues collected from diseased fruits were isolated,purified,and made pathogenicity test,morphological observation, biological and molecular identification. The representive isolate B31, obtained from the diseased fruit, was selected for morphological observation and pathogen identification, and was verified as the causal agent of the scab disease through Koch’s postulates. The result of morphological observation using light microscope showed that the isolate B31 was very similar to Alternaria in terms of hyphae and spore morphology. Phylogenetic analysis results using multiple gene loci showed that identities of sequences of ITS, Alt al, TEF 1 and endoPG genes of isolate B31 were 100% identical to those of Alternaria alternata. This study clarifies that the pathogen causing scab disease of passion fruit in Guangxi is A. alternata, and this is the first report of A. alternate causing scab on passion fruit in China.     

Fusarium crown and root rot of tomatoes in the UK

Fusarium crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 10⁶ spores/plant applied at seed sowing killed 70–83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels.     

Determination of the role of salicylic acid and Benzothiadiazole on physico-chemical alterations caused by <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> in tomato

Shoe-string disease caused by Cucumber mosaic virus (CMV) is one of the major threats to tomato production worldwide. The alteration in some biochemical parameters in leaves of the susceptible tomato genotype (Nagina) associated with CMV infection and the effect of exogenous application of salicylic acid (SA) and benzothiadiazole (BTH) were studied in this paper. Results showed that exogenous treatment with SA and BTH not only led to plants which gave significantly more yield than diseased controls (DC), but also delayed symptom expression and reduced disease severity. Analysis of biochemical parameters indicated that exogenous application of elicitors and viral infection, significantly affected the activity of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Compared to the DC plants, minimum disease severity and maximum number of fruit were recorded after a single dose of SA + BTH. Maximum plant height was recorded after weekly application of SA and maximum fruit yield per plant was gained with single dose of SA. Moreover, the activity of POD was significantly elicited many-fold after weekly application of SA + BTH, while higher amount of SOD was recorded with single dose of SA. The activity of CAT was also significantly accelerated after weekly application of SA + BTH while increased level of APX was noticed with single dose of BTH. In conclusion, the combined application of SA and BTH played an important role in induction of defense mechanism against CMV infection and can be useful in tomato disease management programs.     

短额负蝗为害烟草的经济损失与防治指标研究

采用大田笼罩接虫法研究短额负蝗为害烟草经济损失结果表明，烟株上虫量越大，中上等烟叶下降比率和经济损失越大。单株虫量１、２、４头造成的中上等烟叶下降比例分别是６．０７％、２６．２９％、３９．７２％，经济损失率分别为１４．１７％、３１．８５％、４８．０１％；底叶、下二棚叶、腰叶、上二棚叶、顶叶受害指数分别是１．３９、１３．５４、１８．０６、２５．００、１４．８２。计算出了经济阈值，确定短额负蝗防治指标为６头／１００株