广东新发生流行的水稻橙叶病的鉴定

 1991~1992年广东茂名市的水稻约2万公顷发黄。用电光叶蝉Reclia dorsalis(Motsch)接种3叶龄稻苗,在平均气温28℃下,潜育期为8~36天;主要症状为病株矮,叶片竖直、橙黄至金黄色;部分病叶纵卷干枯;多数病苗早枯死。四环素液浸病稻根可明显延迟死亡。介体昆虫为电光叶蝉。而黑尾蝉Nephotettix cincticeps(Uhler)、二条(大斑)叶蝉N.apicalis(Motsch)和二点叶蝉N.virescence(Distant)以及虱Nilaparvata lugens(Stal)等均不传病。电光叶蝉最短获毒和最短传毒饲育期分别为<2min和<5min.期在室温25~30℃下,约为7~26天,保毒虫能终生传毒,但有间歇传病现象。在病叶脉韧皮筛管细胞毒叶蝉唾腺切片中均可见大量多形态的类菌原体,大小为75~639nm。据此认为本病与1980年云南十年代在东南亚报道的水稻橙叶病基本相同。     

水稻普矮病发生为害原因分析及防治对策

水稻普通矮缩病 (简称普矮病 ) ,近年来在我市局部偶有发生 ,且有逐年加重的趋势 ,今年受去冬今春气温异常影响 ,该病在我市多个乡镇普遍发生 ,全市发病面积达 16 6 6 6 6万ｈｍ2 ,发病较轻的病丛率在 5 %左右 ,重病田块病丛率达 2 0 %～6 0 % ,为近年来发生最严重的 1年。普矮病是由黑尾叶蝉、电光叶蝉、大斑黑尾叶蝉传播病毒而引起的 ,病毒在带毒的黑尾叶蝉若虫体内越冬 ,第 2年春季成虫迁飞到秧地成为初侵染源。感染普矮病的水稻病株显著矮缩 ,分蘖增多 ,叶色浓绿 ,叶质僵硬 ,叶面呈现黄白色条点。1　原因分析(1)气候因素有利虫源越冬、…     

水稻类普矮病的研究Ⅰ.类普矮病——水稻上的一种新的病毒病

 水稻类普矮病在闽西、闽北和闽南均有发生,其为害性不可忽视。病害症状因品种不同而表现为两种基本类型——普矮型和草丛型。将类普矮病和普矮病接种在同一稻苗上.可先后产生各自的症状。
病害仅能通过黑尾叶蝉和二点黑尾叶蝉传播。电光叶蝉、白翅叶蝉、褐飞虱和缢管蚜均不传病。     

广东水稻橙叶病病原(MLO)的越冬

研究结果表明,广东水稻橙叶病病原(MLO)的传染介体和越冬介体昆虫只有电光叶蝉(Recilia dorsalis)一种,但其卵不传递该病原到子代若虫,越冬寄主植物只有水稻的再生稻株和落粒自生稻株。在茂名病区的冬、春期间电光叶蝉的带菌虫和带菌再生稻及感病落粒自生稻始终存在,其带菌率分别为2.33％—35.11％、2.37％—17.78％和1.95％—16.67％。在茂名地区由于冬、春气温不甚低,电光叶蝉仍能继续繁殖越冬,并能不断获菌和传病,所以说该病原是动态越冬的。室内试验表明,带菌电光叶蝉的寿命可长达105—125天,而在茂名的秋收期至翌年春播期一般105天,据此推测有些带菌虫可从秋收后直接存活和传病原到春播稻苗。看麦娘(Alopecurus aequalis)用电光叶蝉人工接种并回接水稻成功。但在病区田间调查从未发现病株。以下植物人工接种不成功:野生稻(Oryzea rufipogon)、小麦(Triticum aestivum)、玉米(Zea mays)、李氏禾(Leersia hexandra)、稗草(Echinochloa crus-gallis)。     

水稻瘤矮病—广东湛江新发生的一种水稻病毒病

 广东新发生的水稻瘤矮病于1981~1982年在广东湛江地区的信宜、高州和化州县发生流行。室内用叶蝉接种2叶龄的稻苗,在10~11月广州温室温度约为土9~23℃下,潜育期为13~28天,主要症状为病苗矮缩,叶片浓绿色,叶背及叶鞘上长有若干个淡黄绿色近圆形小瘤(0.1~1.2毫米直径)。病毒粒子球状,直径约60毫微米。昆虫介体为电光叶蝉(Recilia dorsalis Motsch.)和黑尾叶蝉(Nephotettix cinticeps Uhler.)。褐稻虱(Nilaparvata lugens Stal.)和白背飞虱(Sagatella furcifera Horvath.)不能传病。二点黑尾叶蝉(N.virescence Distant.)和大斑黑尾叶蝉(N.apicalis Motsch)还有待进一步研究决定。电光叶蝉的最短获毒饲育期少于24小时。潜育期在平均室温22~23℃下为13~24天。保毒虫能终生传毒。根据上述实验结果,初步认为本病与泰国和马来西亚报道的水稻瘤矮病相同。     

广东桉树黄化(丛枝)病植原体分子鉴定与检测

从表现黄化(丛枝)症状的桉树上采集病叶,抽提主脉总DNA,采用植原体通用引物与巢式引物进行PCR和巢式PCR扩增,对扩增产物进行克隆和序列测定,获得了植原体的近全长16S rRNA基因及部分16～23S rRNA基因间隔区序列.序列分析揭示,所获得的序列与已知植原体基因组相应区段的序列高度同源,与柳叶菜变叶植原体(epilobium phyllody)和白腊树丛枝植原体(ash witches'-broom)相应序列(GenBank登录号:AY101386和AY566302)同源率为99.9%,与白腊树黄化植原体(aster yellows BD2)相应序列和番茄巨芽植原体(tomato big bud)相应序列同源率分别为99.6%和99.3%.该序列构建的系统进化树表明,引起我国广州地区桉树黄化(丛枝)病的植原体属于16SrI组(即翠菊黄化组),将其暂命名为桉树黄化(丛枝)植原体广东株系(Eucalyp-tus yellowing and witches'-broom phytoplasma strain Guangdong,EYWB-Gd).建立了桉树植原体巢式PCR检测方法,对疑似病样及桉树组培苗进行了检测,多数疑似病样检测结果为阳性,供试的10株组培苗未发现阳性样品.     

紫花苜蓿丛枝病植原体的分子检测及鉴定

 利用植原体16S rRNA基因通用引物对云南昆明发生的苜蓿丛枝病感病植株总DNA进行巢式PCR扩增,得到1.2kb的特异片段,从分子水平证实了苜蓿丛枝病的病原是植原体。从PCR产物的RFLP酶切图谱可看出,该植原体株系的酶切图谱与马里兰翠菊黄化植原体(AY1)相同。对扩增片段进行克隆及序列测定后,利用最小进化法做Bootstrap验证的系统进化树,表明苜蓿丛枝病植原体为Candidatus Phytoplasma asteris成员之一,与植原体16SrI-B亚组成员关系密切。     

黑尾叶蝉NcPGRP基因克隆及表达模式分析

为明确黑尾叶蝉肽聚糖识别蛋白(Nephotettix cincticeps peptidoglycan recognition protein,Nc PGRP)的功能,利用RT-PCR克隆长度为552 bp的Nc PGRP开放阅读框,其编码蛋白大小为19.9 k D,无信号肽,含3个锌离子结合/酰胺酶催化位点,1个二氨基庚二酸型(Dap型)肽聚糖识别位点。系统发育分析表明,Nc PGRP与其他昆虫亲缘关系较远。利用显微注射技术对黑尾叶蝉进行病原细菌诱导,定量PCR结果显示Nc PGRP在受大肠杆菌及藤黄微球菌刺激后,其转录水平显著上调。组织分布研究表明,Nc PGRP的m RNA在各组织中均有表达,且头部表达量最高。黑尾叶蝉取食感染水稻普通矮缩病毒RDV的水稻后,Nc PGRP转录水平受抑制。本文研究表明,Nc PGRP是一种诱导型表达的PGRP,黑尾叶蝉感染RDV能显著抑制其转录,进而削弱黑尾叶蝉免疫能力,这可能有利于RDV与黑尾叶蝉共生。     

水稻矮缩病的研究——Ⅰ.病史、病状和传播

水稻矮缩病(RDV)是七十年代在长江中、下游稻区流行的一种病毒病,常与黄矮病(RYSV)并发,造成双季晚稻严重减产。其病状有白点型和扭缺型两类,前者叶片呈现断续虚线条状的白点,后者心叶或叶尖成螺旋状扭曲或叶缘现缺刻。本病由黑尾叶蝉(Nephotettix cincticeps)、大斑黑尾叶蝉(N.nigropictus)和电光叶蝉(Recilia dorsalis)传染。黑尾叶蝉最短吸毒时间为5分钟,循回期平均12.4天(29.2℃)和17天(20.0℃)。带毒虫多数基本上连续传毒直至死亡。经卵传递虫率高达74.4～88.5%,经卵传毒若虫少数在孵化的当天,多数在孵化后的第6～8天开始传毒。各地虫子对病毒的亲和力不同。     

水稻条纹花叶病田间调查及分子检测

水稻条纹花叶病(Rice stripe mosaic disease)是近年在华南地区新发现的水稻病毒病。该病由电光叶蝉(Recilia dorsalis)以持久增殖型方式传播。2017年至2018年,连续两年的调查结果表明,该病害广泛分布于华南稻区,以广东西南和广西东南部发生较重。室内人工接种和田间病株观察揭示,该病的症状主要表现为病株轻度矮化,叶片呈淡黄色条纹或花叶,重病株叶片基部扭转畸形,抽穗不完全,籽粒不饱满。根据病毒复制酶(L)基因设计一对特异引物(RSMV-L-F:5′-CTCCAACTATCATCCGCTATGC-3′;RSMV-L-R:5′-CCATCCGAGATAAGGTCACTGT-3′),经RT-PCR可对水稻病株及叶蝉体内的病原病毒进行快速、准确的检测。     

2009年造成湖南省水稻大面积矮缩的是南方水稻黑条矮缩病

2009年在湖南省大面积发生一种水稻病毒病,其症状表现为植株矮缩、叶色深绿、高位分蘖、茎秆出现乳白色或浅褐色点条状突起、茎节上出现气生须根。电镜结果表明:在病株韧皮部可见具斐济病毒特征性晶格状排列球状病毒粒体。病毒基因组S10片段部分序列的相似性比对与系统进化树分析表明,该病害是南方水稻黑条矮缩病。     

Causal Role of Xylella fastidiosa in Oleander Leaf Scorch Disease

ABSTRACT A lethal leaf scorch disease of oleander (Nerium oleander) appeared in southern California in 1993. A bacterium, Xylella fastidiosa, was detected by culturing, enzyme-linked immunoassay, and polymerase chain reaction in most symptomatic plants but not in symptomless plants or negative controls. Inoculating oleanders mechanically with X. fastidiosa cultures from diseased oleanders caused oleander leaf scorch (OLS) disease. The bacterium was reisolated from inoculated plants that became diseased. Three species of xylem sap-feeding leafhoppers transmitted the bacterium from oleander to oleander. The bacterium multiplied, moved systemically, and caused wilting in Madagascar periwinkle (Catharanthus rosea) and leaf scorch in periwinkle (Vinca major) in a greenhouse after inoculation with needle puncture. No bacterium was reisolated from grapevine (Vitis vinifera), peach (Prunus persica), olive (Olea europaea), California blackberry (Rubus ursinus), or valley oak (Quercus lobata) mechanically inoculated with OLS strains of X. fastidiosa. A 500-bp sequence of the 16S-23S ribosomal intergenic region of oleander strains showed 99.2% identity with Pierce's disease strains, 98.4% identity with oak leaf scorch strains, and 98.6% identity with phony peach, plum leaf scald, and almond leaf scorch strains.     

海南红麻曲叶病的病原检测与鉴定

 红麻曲叶病是2012年在海南省海口市发现的一种新病害,病株表现为叶片向上卷曲、叶脉肿大、叶脉变深绿色等症状。PCR检测结果显示,该病样中均存在菜豆金色花叶病毒属病毒。基因克隆及序列分析结果表明,该病毒分离物(HN08)基因组仅含A组分(DNA-A),其全长为2 738 nt,与木尔坦棉花曲叶病毒(CLCuMuV)各分离物的相似性均大于89.0 %,其中与中国各分离物的相似性均大于99.0 %。该病毒分离物也伴随有β卫星分子,其全长为1 346 nt,与CLCuMuV各分离物伴随的β卫星分子(CLCuMuB)序列相似性大于83.0 %,其中与分离物Fz1的序列相似性最高,为99.7 %。构建了HN08 DNA-A及其β卫星分子侵染性克隆,通过农杆菌注射接种红麻,接种后30 d,HN08 DNA-A及其β卫星分子混合接种的红麻植株新出叶片开始产生曲叶症状;接种后60 d,二者混合接种的植株大部分叶片表现为严重的曲叶症状,且与田间自然病株症状相同,而二者各自单独接种的红麻植株没有产生明显的症状。PCR及Southern blot检测进一步证实这些症状是由HN08 DNA-A及其β卫星分子的共同侵染引起的。因此,海南红麻曲叶病是由CLCuMuV及其伴随的β卫星分子(CLCuMuB)共同侵染引起的。本文首次报道了红麻是CLCuMuV自然新寄主。     

Retention of Rice dwarf virus by Descendants of Pairs of Viruliferous Vector Insects After Rearing for 6 Years

ABSTRACT Rice dwarf virus (RDV) is characterized by its unusual ability to multiply in both plants and leafhopper vector insects and by its transovarial mode of transmission. Colonies of Nephotettix cincticeps, derived originally from pairs of leafhoppers infected with an ordinary strain of RDV, were maintained for 6 years in the laboratory and were found, at the end of this time, still to harbor RDV. Moreover, the isolate of RDV, designated RDV-I, obtained from these colonies retained the ability to infect rice plants. When we raised leafhoppers separately from eggs that had been placed individually on pieces of water-soaked filter paper and reared them in the presence of healthy rice seedlings, we found that all of these leafhoppers harbored RDV. This observation suggested that RDV-I had been maintained in the leafhoppers by transovarial transmission. Two further observations, namely, the low rate of acquisition of RDV by virus-free insect nymphs on symptomless plants on which viruliferous insects had been reared, and the fact that only 2 to 5% of plants had symptoms when rice seedlings were inoculated via RDV-I-viruliferous insects, confirmed that the maintenance of RDV-I by any other mode of transmission through plants and insects was unlikely. This efficient and long-term maintenance of RDV in a population of viruliferous insects might explain the prolonged duration of rice dwarf disease in the field, once there has been a serious outbreak.     

丁香卷叶病植原体的分子鉴定

 通过透射电子显微镜,在表现卷叶、褪绿症状的丁香(Syringa oblata)样品的叶脉韧皮部筛管细胞内观察到大量植原体粒子。应用植原体16S rRNA基因通用引物对P1/P7和R16F2n/R16R2对表症丁香植株总DNA进行巢式PCR扩增,得到了约1.2 kb的目标片段,通过对扩增片段进行测序、系统发育分析和同源性分析,结果表明,该片段长度为1 246 bp,在系统发育进化树上与翠菊黄化组（Candidatus Phytoplasma asteris）成员是聚集在一起的,与该组成员同源性均在98%以上。用16Sr RNAⅠ组和Ⅴ组特异引物确定了该病害非混合侵染所致,相似性系数和RFLP分析表明该植原体属于16SrⅠ B亚组。这是国内关于翠菊黄化组植原体在丁香上感染的首次报道。     

60%吡虫啉悬浮拌种剂(高巧)对防治水稻飞虱和预防病毒病的效果评价

试验通过用60%吡虫啉悬浮拌种剂(高巧)等药剂进行拌种,考究其对水稻飞虱、稻蓟马、恶苗病的防治以及南方水稻黑条矮缩病、锯齿叶矮缩病等病毒病的预防效果。试验结果表明:高巧种子处理剂对防治水稻秧苗期稻飞虱和预防"南矮"的发生有较好的作用,且对水稻体质有一定的促进作用,主要体现在可促进叶片和根系的生长,进而促进植株分蘖数、株高、地上和地下部分鲜重、茎基宽和产量结构的提高,最终提高水稻产量。     

Transmission of ‘Candidatus Phytoplasma pyri’ by naturally infected Cacopsylla pyri to peach,an approach to the epidemiology of peach yellow leaf roll (PYLR) in Spain

Peach orchards in the northeast of Spain were severely affected in 2012 by a previously unreported disease in this area. The symptoms included early reddening, leaf curling, decline, abnormal fruits, and in some cases death of the peach trees. All the infected peach samples were positive for ‘Candidatus Phytoplasma pyri’, but none were infected by the ‘Ca. Phytoplasma prunorum’. In this work, potential vectors able to transmit ‘Ca. Phytoplasma pyri’ from pear to peach and between peach trees were studied and their infective potential was analysed at different times of the year. Transmission trials of the phytoplasma with potential vectors to an artificial feeding medium for insects and to healthy peach trees were conducted. Additionally, isolated phytoplasmas were genetically characterized to determine which isolates were able to infect peach trees. Results showed that the only insect species captured inside peach plots that was a carrier of the ‘Ca. Phytoplasma pyri’ phytoplasma was Cacopsylla pyri. Other insect species captured and known to be phytoplasma transmitters were present in very low numbers, and were not infected with ‘Ca. Phytoplasma pyri’ phytoplasma. A total of 1928 individuals of C. pyri were captured in the peach orchards, of which around 49% were phytoplasma carriers. All the peach trees exposed to C. pyri in 2014, and 65% in 2015, were infected by ‘Ca. Phytoplasma pyri’ 1 year after exposure, showing that this species is able to transmit the phytoplasma to peach. Molecular characterization showed that some genotypes are preferentially determined in peach.     

水稻簇矮病的研究Ⅴ.病害的年际变化

 病区四个县和非病区一个县1976~1990年的调查、研究结果表明,水稻簇矮病毒(RBSV病害的发生、消长在年际间存在着很大的差异,这种差异随着稻株易感阶段介体叶蝉的种群数量及其传病潜能一一带毒率、亲和率和传毒天率的变化而变化。有的年份虽然介体叶蝉带毒率不高,但其绝对虫口密度大,也能导致病害的严重发生。