玉米大斑病菌亲环素基因的克隆及表达规律分析

利用简并引物PCR结合RACE技术获得S. turcica中亲环素基因的全长,并通过Real-time PCR技术检测该基因在病菌侵染结构发育过程中的表达模式。结果表明,玉米大斑病菌亲环素基因开放阅读框全长1 125 bp,3′UTR 154 bp,5′UTR 93 bp,编码374个氨基酸,将此基因命名为CyPs1,并将其cDNA序列提交GenBank,获得登录号EU679371.1,Protein ID为ACD62431.1。系统发育树分析显示,CyPs1与玉米小斑病菌(Bipolaris maydis)、蓝莓枯枝病菌(Neofusicoccum parvum)等物种的亲环素同源性可达到90%以上。该基因在病菌分生孢子萌发、附着胞形成及侵染阶段均有表达,至附着胞形成和侵染菌丝形成阶段,转录水平分别升至分生孢子时期的2倍和3倍。     

酸碱度对StRALF基因表达量的影响及初步分析

快速碱化因子(RALF)是一种能够参与植物发育调控的植物肽激素,在真菌中也广泛存在并且影响真菌对寄主的侵染状况。通过外源添加酸碱来明确pH值对玉米大斑菌生长的影响,使用实时荧光定量PCR技术分析玉米大斑病菌中StRALF基因在外源添加酸、碱时表达量的变化。运用预测网站对克隆得到的StRALF基因编码区蛋白序列的基本性质进行分析。结果表明,玉米大斑瓋菌在碱性环境下生长状态较好。碱性条件下,StRALF基因比酸性条件下基因表达量高。在侵染寄主过程中,96 h及以后表达量达到最大。经预测分析,初步确定其为分泌蛋白或膜蛋白。在弱碱性条件下,StRALF基因表达量较高并参与侵染过程及侵染后的生长阶段。     

吉林省玉米灰斑病菌的致病性分化研究

选用9个自交系材料作为玉米灰斑病致病性分化的鉴别寄主,对采自吉林省不同地区的14个菌株进行致病性分化研究。结果表明,不同菌株侵染寄主病斑表现不同的反应型,不同菌株间致病力存在差异。根据在鉴别寄主上的发病等级可将吉林省玉米灰斑病菌菌株分为5个致病类群,其中,Ⅰ为强致病类型,包括1号和8号菌株;Ⅱ、Ⅲ为中等致病类群,包括7、9、10、12、13、14号6个菌株;Ⅳ、Ⅴ为弱致病类群,包括2、3、4、5、6、11号菌株。玉米灰斑病菌存在明显的致病分化现象。     

三唑酮种衣剂对小麦幼苗上白粉病菌萌发和侵染影响的组织学观察

采用组织病理学染色技术 ,观察和测定了三唑酮种衣剂包衣处理的小麦幼苗上白粉病菌孢子萌发、侵染的发展过程。结果表明 ,药剂处理对白粉病菌初生芽管、附着胞芽管的萌发及成熟附着胞的形成无抑制作用 ,但明显提高附着胞的畸形率 ;抑制初生吸器原体的形成和指状体的发育 ,降低入侵率 ;抑制初生菌丝的发育、次生菌丝和次生吸器的形成。分析认为 ,三唑酮种衣剂包衣处理在降低小麦白粉病菌的初始菌源数量和控制白粉病的流行危害中具有重要作用     

特异性MAPK抑制剂U0126对玉米大斑病菌细胞膜透性及防御酶活性的影响

依据实验室前期研究发现,MAPK特异性抑制剂U0126对玉米大斑病菌分生孢子及附着胞发育、HT-毒素的产生和活性以及致病性都有着较显著的影响。以不同浓度的U0126处理玉米大斑病菌菌株,研究该抑制剂对病菌细胞膜透性及防御酶活性的影响。结果表明,U0126对病菌菌丝电导率和PAL活性均无显著影响,但对POD及PPO活性均有显著影响,且U0126对POD活性的影响具有浓度依赖性,即低浓度U0126可提高POD活性,高浓度U0126抑制POD活性;U0126对PPO活性的影响具有菌株特异性,且对菌株01-27的PPO活性的影响与对POD活性的影响相似,都具有浓度依赖性;随着U0126浓度增加菌株01-19的PPO活性反而显著下降。U0126对玉米大斑病菌细胞膜透性和苯丙氨酸代谢没有显著影响,但与过氧化物代谢和多酚代谢密切相关;U0126对过氧化物代谢和多酚代谢的影响具有一定的菌株特异性和浓度依赖性。     

玉米大斑病菌对广州地区甜玉米的致病性观测

通过对桂甜和华珍两个甜玉米品种的玉米大斑病病斑扩展速率及病情指数的研究结果表明,不同品种对玉米大斑病菌的抗性存在明显的差异;病斑的产孢特性显示,病斑首次产孢量显著高于再次产孢量。通过比较不同温度下的菌丝生长量,分析出广州地区玉米大斑病菌的主要构成属于高温型。     

玉米灰斑病菌与不同玉米品种互作后纤维素酶活性的变化

采用比色法测定玉米灰斑病菌06-09菌株与不同抗性玉米品种互作3代后再分离菌胞内和胞外纤维素酶(C1和Cx)活性的变化。结果表明,互作当代再分离菌纤维素酶活性的变化均与寄主的抗感性无密切关系;与对照06-09原菌株比较,互作第2代和第3代再分离菌的胞外C1和Cx酶活性均升高;对于同一互作品种,互作第2代和第3代的酶活性明显高于第1代,第2代酶活性最高,说明病菌与同一寄主互作后,其致病性增强,但随着互作代数的继续增加,致病性将逐渐降低。     

黑龙江玉米大斑病菌生理分化研究

用常规鉴别寄主鉴定方法对2005年和2006年采自黑龙江省玉米主产区的48个大斑病菌菌株进行生理分化鉴定。结果表明,在黑龙江玉米产区鉴定出0、1、12、13、23N、123共6个生理小种。黑龙江玉米大斑病菌以0号生理小种为主,所占比例为52.08%;但其他小种有上升为优势小种的趋势,如1、12、13号小种所占比例分别为22.92%、10.42%和8.33%。说明黑龙江玉米产区玉米大斑病菌生理分化组成已发生变化,并且出现了克服多个抗性基因的生理小种,小种毒性组成呈复杂化。     

核盘菌(Sclerotinia sclerotiorum)在大豆叶片上致病过程的初步电镜观察

通过电子显微镜观察核盘菌在大豆叶片上的侵染过程,初步发现该病菌首先在大豆叶表面上形成复合附着器。该附着器可能产生某些酶类软化溶解大豆叶表面,以帮助该病菌侵入叶片内。侵入叶片以后,该病菌既能在叶肉细胞间又能在叶肉细胞内生长。在此过程中,该菌仍借助于酶的分解作用破坏寄主组织,直至再突破叶面角质层,出现在叶面上。然后该菌在叶面上形成菌核。在大豆不同生育期,该病原侵染寄主大豆的速度有所不同。苗期最快,花期最慢。     

橡胶炭疽病菌致病相关突变体的筛选及表型分析

通过对实验室已获得的1 685个橡胶炭疽病菌T-DNA插入突变体的生物学及致病性测定,从中筛选出15个致病力明显减弱的突变体,并进行PCR检测。结果表明,该基因组中均含潮霉素磷酸转移酶基因片段。在PDA培养基上,其中2个突变体菌落颜色异常,6个生长速率下降,8个产孢量显著降低,2个突变体分生孢子形态异常,2个附着胞形态异常,3个不能形成附着胞,在洋葱表皮上,侵染钉形成率显著降低。     

Extreme resistance to infection by potato virus X in genotypes of wild tuber-bearingSolanum species

Summary Clones derived from thirty-one different accessions (nineteen of Argentine origin) belonging to eightSolanum species were screened for resistance to infection by potato virus X strain cp (PVX cp) by mechanical inoculation of plantlets that had been micropropagated in vitro. Estimates of PVX multiplication obtained by enzyme linked immunosorbent assay and slot blot nucleic acid hybridization allowed the identification of resistant clones derived from five accessions belonging toS. commersonii S. oplocense, S. sparsipilum andS. tuberosum andigena. Resistant genotypes supported PVX concentrations 5 to 15 times smaller than did the susceptible control cultivar Spunta. Graft inoculation test confirmed the presence of extreme resistance similar to that conferred by the ‘immunity’ gene X¹ (also called RX_act).     

Studies on natural repellents against potato tuber moth (Phthorimaea operculella Zeller) in country stores

Summary The effects of the leaves of five plant species, one from each of the generaAmbrosia, Anemone, Eupatorium, Eucalyptus andLantana, on potato tuber moth were investigated under indigenous storage conditions at the Central Potato Research Station, Shillong (1800 m above sea level). Their action was compared with that of a biological insecticide (spores ofBacillus thuringiensis), a chemical insecticide (carbaryl), and an untreated control. The data collected after six months storage on tuber damage, sprout damage and the rotting indicated that the leaves ofLantana aculeata provided most protection to the tubers, reducing damage from over 70% in the check to below 5%, and sprout damage from over 45% to below 3%. Next best wasEucalyptus globulus followed byB. thuringiensis. They may be used on tubers stored for table use or for seed as they had no adverse effect on germination or on the yield of a subsequent crop.     

Mineral composition of some traditional Mexican teas

Teas of plant origin traditionally consumed by the Mountain Pima of Chihuahua, Mexico, were analyzed for mineral nutritional content. Fe, Cu, Zn, Ca, and Mg composition was determined for native teas made from shoots ofTagetes lucida, T. filifolia, Elytraria imbricata, andHolodiscus dumosus, and from root xylem ofCeanothus depressus andPhaseolus ritensis. Native uses of these teas are also described.     

In vitro antimicrobial activity of different accessions ofSolanum commersonii Dun. from Uruguay

Summary The in vitro antimicrobial activity of extracts from accessions ofSolanum commersonii Dun. collected in the south of Uruguay was investigated against five microorganisms including the pathogenRalstonia solanacearum. A total of 30 extracts corresponding to organic and aqueous extracts were studied. Interestingly, most of the positive results for growth inhibition were againstR. solanacearum. The extracts were also analyzed for the presence of glycoalkaloids and lectins. Six of the ten aqueous extracts showed lectin presence and a wide variation in the type and amounts of glycoalkaloids, was found. Results indicate that there is no clear relationship between the antimicrobial activity against the five microorganisms screened and the presence or amounts of lectins and glycoalkaloids, traditionally regarded as possible antimicrobial metabolites in theSolanum genus, which indicates the presence of as yet unidentified antimicrobial compounds.     

先玉335、郑单958和京科968抗虫能力的比较研究

以先玉335、郑单958、京科968为材料,以玉米螟(Ostrinia furnacalis)、黏虫(Mythimna separata)和禾谷缢管蚜(Rhopalosiphum padi)为供试昆虫,探究玉米品系大喇叭口期对玉米螟和黏虫及抽雄期对禾谷缢管蚜抗性差异,测定其主要抗虫化合物丁布类物质的含量。结果发现,京科968对玉米螟及禾谷缢管蚜抗性均高于另外两个品系;对黏虫的抗性,郑单958和京科968高于先玉335。大喇叭口期京科968中丁布类物质含量最高,抽雄期郑单958和京科968中主要丁布成分含量均高于先玉335,上述组织中丁布合成相关基因在郑单958及京科968中的表达量也均高于先玉335。本研究揭示杂交玉米抗虫性与抗性相关化合物含量及其相关基因表达间存在正向相关关系,为抗虫玉米分子育种提供理论参考。     

Effect of a continuous hot water treatment of potato tubers on seed-borne fungal pathogens

Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.     

Evaluation of fungicides to control Petri disease pathogens in the grapevine propagation process

The efficacy of fourteen selected fungicides against Phaeomoniella chlamydospora and Phaeoacremonium aleophilum was evaluated in vitro by mycelial growth and conidial germination assays. Azoxystrobin, carbendazim and tebuconazole were the most effective fungicides against P. chlamydospora, while carbendazim and didecyldimethylammonium chloride were the most effective against P. aleophilum. An assay was also conducted with cubiet, hydroxyquinoline sulphate and didecyldimethylammonium chloride to determine their potential to prevent infections caused by these pathogens during the hydration stage in grapevine propagation. The results of this experiment demonstrated that P. chlamydospora and P. aleophilum were able to infect healthy cuttings during the hydration stage and showed that didecyldimethylammonium chloride was consistently the best treatment as a disinfectant soak for grapevine cuttings. Additionally, semi-commercial trials were conducted in two grapevine nurseries to evaluate the effectiveness of several strategies with carbendazim, flusilazole and hydroxyquinoline sulphate at different nursery stages. Soaking planting material in carbendazim during the hydration stage was the most effective treatment since neither P. chlamydospora nor P. aleophilum were isolated from planting material in either nursery.     

转小麦 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥植株的主要抗旱性研究

核氧还蛋白（nucleoredoxin,NRX）可通过还原目标蛋白的二硫键来调控其生物活性,在植物的生长发育和抗逆境胁迫中发挥着重要作用。蛋白质二硫键异构酶（protein disulfide isomerase,PDI）、h型硫氧还蛋白（h-type thioredoxin,TRXh）和蛋白磷酸酶2A催化亚基（protein phosphatase 2A catalytic subunit,PP2Ac）是小麦核氧还蛋白TaNRX1的互作蛋白。为了明确TaNRX1互作蛋白的抗旱性功能,本研究在拟南芥中过表达了小麦 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因,对野生型和转基因拟南芥的表型和抗旱相关生理指标进行了鉴定。结果表明,干旱胁迫处理后,转 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥的根长、存活率、脯氨酸含量均大于野生型,离体叶片失水率、丙二醛（MAD）含量均小于野生型。二氨基联苯胺（diaminobenzidine,DAB）对H₂O₂组织定位染色结果表明,干旱胁迫处理后,转 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥的H₂O₂含量均低于野生型。上述结果说明,TaNRX1的互作蛋白基因 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D增强了拟南芥对于干旱胁迫的抵抗能力。本研究可为小麦抗旱育种提供候选基因和理论基础。     

玉米灌浆期3种鳞翅目害虫的空间分布

采用网格式取样200株玉米,整株剖秆调查亚洲玉米螟、桃蛀螟和棉铃虫在玉米上的数量,用地统计学的方法分析和模拟它们在田间的水平分布;采用生态位理论分析3种害虫在玉米植株上的生态位和种间竞争。结果表明,亚洲玉米螟、桃蛀螟和3种鳞翅目害虫整体在玉米田中的水平分布分别适合球形、高斯、球形模型拟合,均属于聚集分布。Kriging插值模拟图显示,亚洲玉米螟和桃蛀螟为核心分布型;在垂直分布上,雌穗上3种害虫数量最多,占总虫量的69.82%。亚洲玉米螟的基础生态位宽度最大,在整株玉米上都可危害;桃蛀螟则主要在玉米中、上部;棉铃虫基础生态位最窄,只在雌穗附近危害。3种害虫在玉米茎秆上种间竞争激烈,异种害虫无法共存;雌穗上种间竞争程度小于茎秆,异种害虫可以共存。     

Screening for resistance to early blight (Alternaria solani) in potato (Solanum tuberosum L.) using toxic metabolites produced by the fungus

Summary The phytotoxic components of the culture filtrate of the fungusAlternaria solani Sor, which causes early blight in potato, were used in this study to differentiate between resistant and susceptible genotypes selected to represent a range of reactions when screened in the field. Detached leaflet assays, using spores and toxic metabolites from the culture filtrate, were compared with field ratings and a whole-plant glasshouse test. Rank correlations between several detached leaflet tests were highly significant (P<0.01) but the correlations between these tests and the glasshouse and field tests were poor. The disease ratings obtained in the various tests were clustered into four groups and assigned to resistance classes. For many of the genotypes there was a good correspondence between resistance classes for all test methods. Divergent results between tests were associated with foliage maturity characteristics of the genotypes. Contribution no. 3879050 of the Lethbridge Research Station.