饥饿及取食不同植物后莲草直胸跳甲消化酶差异表达基因筛选

为探究莲草直胸跳甲Agasicles hygrophila体内与寄主专一性相关的消化酶基因,利用前期构建的转录组数据库筛选差异表达的消化酶基因,采用实时荧光定量PCR检测饥饿及取食喜旱莲子草Alternanthera philoxeroides、莲子草Al. sessilis、甜菜Beta vulgaris、莙荙B. v. var. cicla后莲草直胸跳甲成虫体内差异表达消化酶基因的表达量。结果显示,转录组分析共搜索到221个与消化相关的基因,主要编码脂肪酶和蛋白酶;进一步筛选到编码蛋白酶、脂肪酶和糖酶3大类的26个差异表达的消化酶基因。与取食寄主植物喜旱莲子草相比,取食不同非寄主植物和饥饿处理后莲草直胸跳甲成虫体内消化酶基因表达量发生显著变化。除β-半乳糖苷酶(β-galactosidase,β-Gal)基因外,取食不同植物及饥饿处理后莲草直胸跳甲成虫体内4个胰蛋白酶(trypsin,Try)、5个氨肽酶(aminopeptidase,Am)、8个脂肪酶(lipase,Lip)、5个β-葡萄糖苷酶(β-glucosidase,β-Glu)和1个α-葡萄糖苷酶(α-glucosida...     

莲草直胸跳甲羧酸酯酶基因AhCesB1的克隆、序列分析及表达特征

莲草直胸跳甲Agasicles hygrophila是入侵杂草喜旱莲子草的专食性天敌。为进一步明确莲草直胸跳甲寄主专一性的分子机制,通过分析其转录组数据克隆羧酸酯酶(carboxylesterases,Car Es)基因,采用RT-PCR技术从其体内获得1个羧酸酯酶B簇基因并进行生物信息学分析,同时利用实时定量PCR方法检测其在不同身体部位及不同发育阶段的表达特性,并对饥饿处理、取食靶标植物喜旱莲子草和非靶标植物莙荙后该基因的表达水平进行比较。结果显示,克隆得到1条莲草直胸跳甲羧酸酯酶基因的cDNA全长序列,长度为1 851 bp,开放阅读框长度为1 647 bp,编码548个氨基酸,以该基因推导的氨基酸序列与其它物种的CarEs进行聚类分析,发现此基因为羧酸酯酶B簇家族成员,命名为AhCesB1(GenBank登录号KT032151)。实时定量PCR检测结果显示,AhCesB1基因在莲草直胸跳甲3龄期表达量最高,成虫期和蛹期表达量次之,卵、1龄和2龄期表达量相对较低。AhCesB1基因在头和中肠的表达量较低,在其余身体部分表达量较高。取食莙荙后AhCesB1表达量显著增高,为饥饿处理的13.7倍,而取食喜旱莲子草与饥饿处理并无显著差异。表明莲草直胸跳甲AhCesB1在不同发育阶段和成虫不同身体部位具有不同的表达水平,而非寄主植物莙荙可以诱导该基因的表达,推测羧酸酯酶在莲草直胸跳甲代谢次生物质中发挥着重要作用。     

莲草直胸跳甲在几种非靶标植物上的适合度比较

莲草直胸跳甲是防治入侵杂草喜旱莲子草的引进天敌,为检测莲草直胸跳甲对非靶标植物的影响,选取了29种具有代表性的植物对该天敌进行了3种选择和1种非选择性压力的测试.在全组植物或移除喜旱莲子草组中,莲草直胸跳甲成虫和幼虫对喜旱莲子草和非靶标近缘种莲子草的取食面积均显著大于其它非靶标植物,幼虫还可取食非靶标植物若蘧、反枝苋等;成虫在无喜旱莲子草时可取食若蘧和甜菜.当移除喜旱莲子草和莲子草时,成虫和幼虫对若蘧和甜菜的取食面积分别提高22.33、4倍和1.76、16.42倍.在非选择测试中,成虫和幼虫对喜旱莲子草和莲子草的取食显著高于其它组,其它植物均不能满足其正常发育和生存.研究表明,莲草直胸跳甲对莲子草属植物的适合度最高.     

利用光谱特征评价莲草直胸跳甲对喜旱莲子草的控制效果

为建立快速有效的喜旱莲子草生物防治效果评价技术体系,采用基于成像光谱遥感技术的多波段光谱辐射仪,研究了利用冠层光谱特征值评价天敌昆虫莲草直胸跳甲Agasicles hygrophila对喜旱莲子草Alternanthera philoxeroides控制效果的方法。结果表明,莲草直胸跳甲取食引起喜旱莲子草冠层光谱变化,在可见光区绿光波段（中心波长约560 nm）和近红外波段（中心波段810 nm）,喜旱莲子草冠层光谱反射率随莲草直胸跳甲密度的增加逐渐下降,而在红光波段（中心波长约660 nm）呈上升趋势。莲草直胸跳甲取食还导致喜旱莲子草植被指数的变化。在近红外区760～810 nm波段莲草直胸跳甲的控制效果与喜旱莲子草冠层光谱反射率呈极显著负相关,相关系数为-0.92,故可将760～810 nm波长范围作为监测莲草直胸跳甲对喜旱莲子草控制效果的敏感波段。     

喜旱莲子草次生代谢物对莲草直胸跳甲谷胱甘肽S-转移酶和淀粉酶活性的影响

为明确喜旱莲子草的次生代谢物对其专食性天敌-莲草直胸跳甲Agasicles hygrophila成虫解毒酶和消化酶的影响,利用不同浓度的橙花叔醇、齐墩果酸和甜菜碱浸叶处理喜旱莲子草Alternanthera philoxeroides,连续饲喂莲草直胸跳甲1~3 d后,测定莲草直胸跳甲谷胱甘肽S-转移酶(GSTs)和淀粉酶(AMS)的活性变化。结果表明,橙花叔醇、齐墩果酸和甜菜碱均能抑制莲草直胸跳甲的GSTs活性,0.1%橙花叔醇和20%甜菜碱处理24 h时的GSTs活性最低,分别为45.67 U/mg和53.95 U/mg,0.2%齐墩果处理72 h时的GSTs活性最低,为98.77 U/mg,且莲草直胸跳甲对橙花叔醇的刺激存在着一种适应机制;0.5%橙花叔醇和0.1%齐墩果酸处理24 h后的GSTs活性最高,分别为243.10 U/mg和250.22 U/mg,是对照的1.55倍和1.59倍,存在诱导激活现象。甜菜碱对莲草直胸跳甲的AMS活性有明显的抑制作用,20%甜菜碱处理72 h后AMS活性最低,为1.01 U/mg,是对照的55.92%。表明喜旱莲子草3种次生代谢物均能抑制谷胱甘肽S-转移酶活性,其中橙花叔醇和齐墩果酸对谷胱甘肽S-转移酶有诱导激活作用,而甜菜碱对淀粉酶抑制作用较强。     

喜旱莲子草天敌——莲草直胸跳甲引种方法介绍

本文论述了作为入侵杂草喜旱莲子草优势天敌——莲草直胸跳甲的长距离和短距离引种方法,对其三种虫态的引种方法分别做了介绍。成虫适宜长距离和短距离引种;幼虫和卵适合做短距离引种。这为成功防治恶性杂草喜旱莲子草提供了技术指导。     

广东莲草直胸跳甲生物学的观察

空心莲子草 ( Alternanthera philoxeroides)为一种多年生恶性杂草 ,属苋科 ,莲子草属 ,在我国各地又名水花生、空心苋、喜旱莲子草等 ,具有繁殖迅速 ,适应性强和难以用化学除草剂根除的特点 [1 ] 。该草原产南美 ,大约本世纪 40年代传入我国 ,现成为南方各省主要恶性杂草 ,已泛滥成灾 ,给农业和水产养殖业造成极大危害 [2 ]。莲草直胸跳甲 ( Agasicles hygrophila)原产阿根廷 ,是空心莲子草的天敌。李宏科等 [3] 报道了莲草直胸跳甲的大量繁殖及释放技术 ,对应用莲草直胸跳甲的可行性作了研究。吴珍泉等 [4]对莲草直胸跳甲生物学特性进行…     

莲草直胸跳甲在不同生态型空心莲子草上的化蛹适应性

对莲草直胸跳甲在不同生态型空心莲子草上化蛹能力的研究表明：美国和重庆种群对不同生态型空心莲子草的化蛹适应性无显著差异；空心莲子草的生态型是影响莲草直胸跳甲化蛹能力的重要因子，在水生型草上化蛹能力显著高于湿生型和旱生型；水生型空心莲子草的直径大小不影响跳甲的化蛹能力，而陆生型空心莲子草的直径是影响其化蛹能力的重要因子；在陆生型草上，随着生长环境水分的降低，莲草直胸跳甲对直径较大的空心莲子草有很强的选择性；该虫在不同生态型草上的化蛹率与化蛹位置有关。莲草直胸跳甲能有效地控制水生型空心莲子草，对陆生型草可起到一定程度的抑制作用。     

真菌防治喜旱莲子草的研究进展

喜旱莲子草是一种危害严重的恶性入侵杂草,生物防治该杂草尤其是引入莲草直胸跳甲后取得很大进展。然而陆生型和高纬度地区的喜旱莲子草的防治仍是难点,利用真菌资源防治该杂草具有潜力。本文概述了对喜旱莲子草有一定生防潜力的真菌,并对其寄主专一性及作用机理进行了总结,提出了目前存在的问题及建议,以期为有效控制该杂草提供指导。     

真菌防治喜旱莲子草研究进展

喜旱莲子草是一种危害严重的恶性入侵杂草,生物防治该杂草尤其是引入莲草直胸跳甲后取得很大进展。然而陆生型和高纬度地区的喜旱莲子草的防治仍是难点,利用真菌资源防治该杂草具有潜力。本文概述了对喜旱莲子草有一定生防潜力的真菌,并对其寄主专一性及作用机理进行了总结,提出了目前存在的问题及建议,以期为有效控制该杂草提供指导。     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Monitoring of the winter populations of cereal aphids near Wageningen,the Netherlands,in 1982/1983

Cereal aphids on a wheat crop were sampled through the winter of 1982/1983 using both fixed and random quadrats.Sitobion avenae overwintered successfully anholocyclically although there was a substantial decline in the population of this species. No evidence for successful anholocyclic overwintering in other aphid species was found, althoughRhopalosiphum padi was seen to colonise the crop in early winter and was found until the end of December.Eggs ofR. padi onPrunus padus were observed through the winter. A steady decline in their numbers occurred. The overall survival rate of the 5385 eggs was c.30%.Eggs ofMetopolophium dirhodum onRosa spp. were also monitored. They also showed a steady decline in numbers through the winter. The overall survival rate of the 1360 eggs was c.34%.Egg hatch in bothR. padi andM. dirhodum was closely synchronised with bud burst of their host plant. For the latter species this resulted in egg hatch starting in January.Samenvatting In de winter van 1982/1983 werden de graanluizen in een tarwegewas regelmatig geteld in willekeurig en in van tevoren gekozen monstereenheden. Hoewel er een aanmerkelijke afname van de populatie vanSitobion avenae werd waargenomen, overwinterde deze soort toch anholocyclish. Er werden geen aanwijzingen gevonden dat de andere bladluissoorten anholocyclish overwinterden hoewel kolonies vanRhopalosiphum padi tot eind december werden waargenomen.De gehele winter werden eieren vanR. padi opPrunus padi aangetroffen, de aantallen ervan namen geleidelijk af; van de 5385 getelde eieren overleefde ongeveer 30%. Ook de aantallen eieren vanMetopolophium dirhodum opRosa spp. werden reglematig vastgesteld; ook hier werd een geleidelijke afname geconstateerd. Van de oorspronkelijk getelde 1360 eieren overleefde ongeveer 34%.Het uitkomen van de eieren vanR. padi enM. dirhodum viel nauw samen met het uitlopen van de knoppen van hun waardplant. VoorM. dirhodum betekende dit dat de eerste eieren al begin januari uitkwamen.     

Pathogenic fungi involved in root rot of peas in the Netherlands and their physiological specialization

Research on root rot pathogens of peas in the Netherlands has confirmed the prevalence ofFusarium solani, F. oxysporum, Pythium spp.,Mycosphaerella pinodes andPhoma medicaginis var.pinodella. Aphanomyces euteiches andThielaviopsis basicola were identified for the first time as pea pathogens in the Netherlands. Other pathogens such asRhizoctonia solani andCylindrocarpon destructans were also found on diseased parts of roots. F. solani existed in different degrees of pathogenicity, and was sometimes highly specific to pea, dwarf bean of field bean, depending on the cropping history of the field.A. euteiches was specific to peas, whereasT. basicola showed some degree of physiological specialization.     

Detection of the phytotoxin coronatine by ELISA and localization in infected plant tissue

Several pathovars of Pseudomonas syringae produce the phytotoxin coronatine (COR)in vitro, and the availability of purified toxin has facilitated development of immunological detection methods. A modified, indirect competitive ELISA using the COR-specific monoclonal antibody 11B8 was developed to detect COR in various host plants infected by P. syringae. The estimated detection limit for COR was 50 pg per well, and COR could be reliably quantified from 5 to 40 ng ml⁻¹. The subcellular localization of COR within infected tomato tissue was investigated using the COR-specific antibody MAb 8H3G2. Immunofluorescence microscopy and immunogold labelling showed that COR was present inside tomato cells and was associated with chloroplasts and particles of proteinase inhibitor I. Localization studies indicated that COR is mobile in infected plant tissue and can be detected in healthy tissue adjacent to the bacterial lesions.     

Functional analysis of the 3′ end of avrBs3/pthA genes from two Xanthomonas species

The phytopathogens Xanthomonas oryzae pathovar (pv.) oryzae and Xanthomonas axonopodis pv. citri each contain several avrBs3/pthA family genes. Structural features of these genes important for avirulence and/or virulence functions include a central region of multiple direct repeats and three nuclear localization signals (NLSs) and an acidic activation domain (AAD) at the 3′ end. To identify other regions critical to function in the 3′ ends of these genes, we constructed several chimeras using apl1 and apl2 from X. axonopodis pv. citri and avrXa10 and avrXa7 from X. oryzae pv. oryzae and evaluated their functions by inoculation to citrus and rice. The apl1 and avrXa7 genes are major virulence determinants in citrus and rice, respectively, while the contributions of apl2 and avrXa10 to virulence are negligible or not measurable. Constructs that contained a 417 bp HincII-SphI fragment from the 3′ end of apl1 in combination with the repeats from avrXa7, avrXa10, and apl1 caused a canker phenotype on citrus. Interchange of the HincII-SphI fragment between avrXa7 and avrXa10 abolishes avrXa7 avirulence function and reduces its virulence but it does not affect avrXa10 avirulence function in rice. avrXa7 caused a hypersensitive response (HR) in citrus and replacement of it's 3′ end with that of apl1 resulted in loss of canker and induction of HR. Thus, the HincII-SphI fragment of the avrBs3/pthA gene family is important for avirulence and virulence functions in two different plant species, Oryza sativa and Citrus natsudaidai HAYATA.     

Xanthomonas campestris pv. populi,the causal agent of bark necrosis in poplar

A bacterium was isolated from superficial bark necroses on young poplars and its pathogenicity demonstrated by inoculation experiments. The organism was identified asXanthomonas campestris. Cross-inoculations showed that a previously undescribed pathovar was involved. It is suggested to designate this organismX. campestris pv.populi.Samenvatting Uit een oppervlakkige bastnecrose bij jonge populieren werd massaal een bepaalde bacterie geïsoleerd. Met deze bacterie werden gezonde populieren in het veld geïnoculeerd via verwonding van de bast. Als gevolg van de inoculaties ontwikkelden zich bij ongeveer 40% van de geïnoculeerde bomen hetzelfde type bastnecrosen, terwijl bij de controleplanten geen enkele reactie optrad. Uit de kunstmatig verkregen necrosen werd dezelfde bacterie geïsoleerd.Identificatie met biochemische en serologische methoden toonde aan dat de bacterieXanthomonas campestris was.Vervolgens werden in de kas kruisinoculaties uitgevoerd met verschillende xanthomonaden op populier, wilg, kool en geranium. DeX. campestris isolaten uit populier tastten behalve populier ook wilg aan. De andere gebruikte stammen waren waardplant-specifiek, al bleven sommigen ervan minstens acht maanden in leven in een niet-waardplant, evenwel zonder symptomen te veroorzaken. Geconcludeerd wordt, dat de bastnecrosen zijn veroorzaakt door een nog niet beschreven pathovar vanX. campestris. Voorgesteld wordt om deze bacterieXanthomonas campestris pv.populi te noemen.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Aetiology and causal agents of mango sudden decline disease in the Sultanate of Oman

Mango sudden decline is a recently introduced, economically serious disease in Oman. Affected mango trees have wilting symptoms that usually begin on one side and later spread to involve the entire tree. Trees exude amber-coloured gum from the bark of their trunks or branches and vascular tissues are discoloured. Having entered Oman in the recent past, survey data is presented that shows the disease to have spread throughout the northern part of the country. Evidence is presented that the vascular wilt pathogen Ceratocystis fimbriata causes mango sudden decline disease in Oman, possibly in concert with Lasiodiplodia theobromae and the recently described Ceratocystis omanensis. Isolates of these fungi from affected trees, cause infection and can be recovered from inoculated seedlings. Bark beetles (Hypocryphalus mangiferae) are shown to carry C. fimbriata and L. theobromae and are presumably responsible for transmitting both pathogens to healthy mango trees. Acting as a wounding agent and vector, the bark beetle is likely to have assisted the rapid spread of the disease across Oman.     

浅黄恩蚜小蜂和丽蚜小蜂对温室白粉虱的寄生潜能分析

浅黄恩蚜小蜂Encarsia sophia GiraultDodd和丽蚜小蜂Encarsia formosa Gahan是防治粉虱类害虫的优势寄生蜂,通过生命表技术方法分析了2种寄生蜂对温室白粉虱Trialeurodes vaporariorum(Westwood)的防治潜能。结果表明,丽蚜小蜂在羽化第3天和第10天出现2次寄生高峰,占其总寄生量的13.7%和8.0%,在2次高峰之间逐日寄生粉虱数量比较平稳,单雌逐日平均产雌数保持在10.6~13.4头,10 d后寄生量呈明显的下降趋势;而浅黄恩蚜小蜂羽化10 d内逐日寄生粉虱量变化不大,单雌逐日产雌数稳定在4.2~5.4头,羽化14 d后寄生量呈明显下降趋势。丽蚜小蜂和浅黄恩蚜小蜂的R0、T、rm、λ值分别为171.5、18.0、0.2854、1.3303和61.6、16.2、0.2544、1.2897;粉虱若虫充足时,丽蚜小蜂平均单雌寄生若虫数是浅黄恩蚜小蜂的2.7倍,而后者平均单雌取食若虫数为60.6头,明显高于前者42.7头,总的来看,丽蚜小蜂通过寄生和取食杀死粉虱总量220.8头,明显高于浅黄恩蚜小蜂的127.9头。表明在应用寄生蜂防治温室白粉虱时,单独释放丽蚜小蜂比浅黄恩蚜小蜂显示出更好的防治潜能。     

Parasitoid community of the loreyi leaf wormMythimna (Acantholeucania) loreyi: Novel host-parasitoid associations and their efficiency in the eastern mediterranean region of Turkey

The loreyi leaf worm,Mythimna (Acantholeucania) loreyi Duponchel (Lepidoptera, Noctuidae), is a pest of gramineous crops and causes significant economic damage to maize. In field surveys on maize to determine the parasitoid community and its impact on the pest in the eastern Mediterranean region of Turkey, nine parasitoid species were found associated with immature stages ofM. loreyi: The hymenopteran (Braconidae and Ichneumonidae) parasitoidsCotesia (=Apanteles) ruficrus (Haliday),Chelonus oculator Panzer,Meteorus ictericus Nees,Hyposoter didymator (Thunberg),Sinophorus sp.; and the dipteran (Tachinidae) parasitoidsPseudogonia rufifrons Wiedeman,Exorista rossica Mesnil,Gonia picea (Robineau-Desvoidy) andLinnaemya vulpina (Fallen) — the last three recorded for the first time as parasitoids ofM. loreyi in Turkey.C. ruficrus was the dominant parasitoid species, being recovered from 38.5% of the larvae collected and was also the most prevalent species, existing in 91.0% of the fields in whichM. loreyi was found. Total parasitism levels achieved by braconid species was 41.4%, by ichneumonid parasitoids 4.8%, and by tachinid parasitoids 1.9%. In a separate field experiment, seasonal population fluctuations and natural efficiency ofC. ruficrus onM. loreyi were found to be 35.1% and 42.4%, respectively. Population levels ofC. ruficrus were closely related to fluctuations in the population ofM. loreyi, with parasitism ranging between 0 and 77.3% during the study. http://www.phytoparasitica.org posting Aug. 28, 2005.