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.     

玉米黑粉菌菌瘤内内生细菌对黑粉菌的冬孢子萌发的影响

利用高通量测序分析明确玉米黑粉菌菌瘤内菌粉培养液中内生细菌种类，结合16SrDNA分析，分离并鉴定在培养液中占比最高的菌株。以溶菌酶及Amp处理玉米黑粉菌冬孢子为对照，显微镜下观察菌瘤内内生细菌对玉米黑粉菌冬孢子萌发的影响。结果表明，在4份样品的菌粉培养液中，肠杆菌属细菌的占比在90%以上。当肠杆菌大量增殖时对黑粉菌的冬孢子萌发产生影响，可引起黑粉菌的冬孢子发生质壁分离，释放原生质体，部分原生质体再生成菌体；也可以使冬孢子壁直接被降解，原生质体萎缩。研究发现，玉米黑粉菌菌瘤内的内生细菌以肠杆菌为主，该内生细菌对黑粉菌的冬孢子萌发产生影响。     

两种赤眼蜂在甜玉米上的不同释放方式对治亚洲玉米螟效果的影响

为评价玉米植株上不同放蜂位置对两种赤眼蜂防治玉米螟效果的影响,采用盆栽控制试验,分别设置玉米心叶内、盆栽土壤表面及玉米叶片背部3个接蜂点,每点分别单独、混合释放两种赤眼蜂,研究同一蜂种不同释放方式对玉米螟的控害效果。结果表明,在同一位置接蜂,单独接玉米螟赤眼蜂和混合接蜂在卵块寄生率、卵粒寄生率、玉米螟卵中的总出蜂数等指标均高于单独接松毛虫赤眼蜂。当接入蜂种相同而位置不同时,在心叶内接蜂玉米螟卵粒寄生率最高,玉米螟赤眼蜂在心叶内接蜂的蜂卡羽化率高于土壤表面和叶片背部接蜂;松毛虫赤眼蜂在3个位置上差异不显著。在玉米心叶内单独释放玉米螟赤眼蜂或者混合释放赤眼蜂对玉米螟的防治效果最好。     

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.     

河南省3种麦田阔叶杂草对苯磺隆的抗性

为明确河南省冬麦田3种阔叶杂草猪殃殃、播娘蒿、牛繁缕对苯磺隆的抗性水平和分布现状,在温室中采用整株剂量-反应测定法测定了3种杂草的40个种群对苯磺隆的敏感性。结果表明,河南省3种阔叶杂草已普遍对苯磺隆产生抗性,所测样本中,抗性种群27个,占总采样数的67.50%,其中牛繁缕抗性水平最高,猪殃殃居中,播娘蒿最低。豫中和豫南地区3种杂草的整体抗性水平较高,豫西和豫西南抗性水平相对较低。     

Evaluation of fungal epiphytes isolated from banana fruit surfaces for biocontrol of banana crown rot disease

Fungi isolated from the surface of banana fruits were evaluated for in vitro antagonism towards Lasiodiplodia theobromae. Thirteen fungi exhibiting pronounced growth inhibition of test pathogens were further tested for antibiosis against Thielaviopsis paradoxa, Colletotrichum musae, and Fusarium verticillioides. Clonostachys byssicola, Curvularia pallescens, Penicillium oxalicum, and Trichoderma harzianum were antagonistic to all test pathogens. Inhibition by C. pallescens and P. oxalicum to pathogens was at a distance, while C. byssicola and T. harzianum directly parasitized and killed the pathogens. The metabolites of C. byssicola, C. pallescens, and T. harzianum significantly affected the mycelial growth and conidial germination of the pathogens. In the artificial inoculation study, the antagonists survived and colonized banana fruits after 3 d. Interfungal parasitic relationship was observed between the antagonist and pathogen on artificial media and natural substrate. Postharvest application in the packing house showed that the incidence of crown rot in antagonist-treated banana was significantly lower when compared to fungicide and untreated control fruits.     

小麦株高QTL的定位及对重要农艺性状的多效性分析

株高作为小麦育种的重要指标,对产量具有较大的影响。为进一步挖掘小麦株高的数量性状位点（quantitative trait loci,QTL）,本研究以扬麦12和偃展1号杂交得到的包含205个家系的重组自交系（recombinant inbred lines,RIL）群体为材料,利用小麦55K SNP芯片构建高密度遗传图谱,结合 3年共6个环境的表型数据对株高性状进行QTL定位分析。结果表明,在染色体2B（1）、4B（1）、4D（1）、5A（1）、5B（1）和7D（2）上共检测到7个与株高相关的QTL。QPh.yaas-4B、QPh.yaas-5A和QPh.yaas-7D.1的矮秆效应来源于扬麦12,其余4个QTL的矮秆效应来源于偃展1号。在6个环境下都能检测到的位点是QPh.yaas-4B和QPh.yaas-4D,对株高的贡献率分别14.50%~24.09%和19.01%~29.80%,经过比对发现,这2个QTL分别是Rht1和Rht2。QPh.yaas-5A在5个环境下被检测到,对株高的贡献率为3.29%~5.36%;QPh.yaas-2D和QPh.yaas-7D.2在4个环境中均被检测到,对株高的贡献率分别为3.45%~6.14%和3.16%~4.10%;QPh.yaas-5B和QPh.yaas-7D.1分别在2个和3个环境中被检测到,对株高的贡献率分别是2.27%~5.09%和2.72%~4.82%。QTL比较分析后发现,QPh.yaas-7D.1和QPh.yaas-7D.2可能是新的株高位点。研究Rht-B1和Rht-D1对千粒重、穗长和穗粒数的效应,发现Rht-B1位点对这些农艺性状无显著效应,Rht-D1位点仅对千粒重有显著效应,其株高增效等位变异可显著增加千粒重。在自然群体中验证Rht-B1和Rht-D1的效应结果与RIL群体结果一致。     

普通小麦D染色体组上psy基因位点的分子证据

为检测普通小麦D染色体组是否存在psy基因,以扩增普通小麦(2X=AABBDD=42)psy基因的相同引物psy02和psy06在节节麦(2X=DD=14)中进行PCR反应。结果表明,引物psy02在节节麦基因组DNA中的扩增产物长206 bp,与普通小麦中扩增的196 bp序列同源率为93.0%,对应的第2外显子区域内仅有1 SNP;引物psy06在节节麦基因组DNA中的PCR产物长305 bp,与普通小麦中扩增的302 bp序列同源率达95.77%,对应的第6外显子区域内无SNP,说明在小麦D染色体组中存在psy基因,且psy基因部分外显子序列在D染色体组的进化过程中相对保守。     

Evaluation of diploid potato clones for resistance to tuber soft rot induced by strains ofErwinia carotovora subsp.atroseptica,E. carotovora subsp.carotovora andE. chrysanthemi

Summary Tubers of clones from a diploid hybrid population ofSolanum phureja andS. stenotomum were screened for resistance to tuber soft rot caused by strains ofErwinia carotovora subsp.atroseptica (Eca),E. carotovora subsp.carotovora (Ecc) andE. chrysanthemi (Ech). Significant, positive correlations between resistance to the different strains and species were observed, indicating that screening for resistance to tuber soft rot could be accomplished by using just one of the three pathogens. Strains of Ecc and Ech were found to be much more virulent than strains of Eca. Inoculating with Ecc and Ech resulted in more distinct differences among susceptible, moderately resistant and resistant clones than inoculating with Eca.     

Comparison of resistance toFusarium spp. of glasshouse-and field-grown tuber progenies of potato

Summary Field-grown tubers of 22 progenies ofSolanum tuberosum L. generated in a crossing programme involving seven parents differing in resistance toFusarium coeruleum Lib. ex Sacc. andF. sulphureum Schlect. (=F. sambucinum Fuckel, teleomorphGibberella pulicaris (Fr.) Sacc.) were wound-inoculated with a cornmeal + sand culture of each pathogen. Parental genotypes were also included. The mean lesion size of each progeny was compared in 2 years of tests, as well as with published data on glasshouse-grown tubers. ForF. coeruleum there was a high correlation between years as well as with the glasshouse data, but no such correlations were apparent withG. pulicaris. Furthermore, parental and GCA values, as well as progeny means and mid-parent scores, also correlated highly forF. coeruleum but not forG. pulicaris. Glasshouse-grown tubers of 11 wildSolanum spp. were also inoculated with both pathogens. Some resistance to one or other, or both, was apparent, particularly inS. chacoense.     

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).     

Biological factors influencing the transmission of potato leafroll virus by different aphid species

Summary Macrosiphum euphorbiae, collected in the field from potato plants infected with potato leafroll virus (PLRV), transmitted the virus to fewer potato plants in a field trial than did laboratory-rearedMyzus persicae. In the laboratory,M. persicae was the only efficient vector of PLRV fromPhysalis floridana seedlings, potato sprouts or excised leaves toP. floridana. Two clones ofM. euphorbiae and one clone ofAulacorthum solani transmitted PLRV from infected potato plants toNicotiana clevelandii as effeciently asM. persicae but a clone ofAphis gossypii was an inefficient PLRV vector. An isolate of PLRV, whichM. persicae transmitted inefficiently from potato toN. clevelandii, was also transmitted inefficiently byM. euphorbiae andA. solani.     

Effect of haulm treatment and harvest time on incidence of tuber rots of potato (Solanum tuberosum L.) after standard wounding and on frequency of stem lesions caused byPhoma foveata Foister

Summary Various haulm treatments and harvest times differentially influenced the incidence of storage rots in potato tubers (Solanum tuberosum L.) in field experiments in Sweden performed over 4 years. The incidence of gangrene caused byPhoma foveata Foister (Phoma exigua var.foveata (Foister) Boerema) increased in cv. Bellona after spraying haulms with diquat as did the amount of infection caused byFusarium avenaceum (Corda ex. Fr.) Sacc. in all three cultivars (Bintje, Bellona, and Magnum Bonum). The lowestP. foveata infection levels occurred after pulling haulms. Late harvesting increased the frequency ofP. foveata in cvs Bintje and Bellona both at 2 and 4 wks interval between haulm treatment and harvest. Tuber and visible stem infection caused byP. foveata were correlated for cvs Bintje and Bellona, but not for cv. Magnum Bonum. The possible relation between tuber and stem infection is discussed.     

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.     

Wild tuber-bearing species ofSolanum and incidence ofPhytophthora infestans (Mont.) de Bary on the Western slopes of the volcano Nevado de Toluca. 5. Type of resistance toP. infestans

Summary Plants of wildSolanum species (S. demissum (dms), S. verrucosum (ver), S. iopetalum (iop), S. brachycarpum (bra), and an unidentified species (unsp), from the natural habitat were inoculated in the laboratory withPhytophthora infestans race 0, to see if major genes for resistance were present, and with the most complex and aggressive race available in an attempt to reveal the level of general resistance. No plant with a susceptible reaction to race 0 was found in 120 plants ofdms, and 34 plants ofunsp. Plants with a hypersensitive reaction to race 0 and susceptible plants were found inver. When infected with a complex aggressive isolate of the fungus 73.5% of the WSS plants were susceptible. It was concluded that WSS in the area possess both complex race specific resistance and a high level of general resistance, whose effects cannot yet be separated.     

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。     

小麦LEAsm基因及其启动子的克隆与功能研究

胚胎发育晚期丰富蛋白(LEA)是一个小的高亲水性的蛋白家族,该蛋白家族在逆境胁迫下大量积累,保护植物免受逆境胁迫。LEA蛋白可分为7组,其中重复的11-氨基酸基序是第3组LEA蛋白的特征。为深入分析第3组LEA蛋白在小麦响应逆境胁迫中的作用机制,利用芯片技术从小麦表达谱中筛选出一个渗透胁迫诱导表达的第3组LEA蛋白基因TaLEAsm,然后根据该基因序列设计引物筛选石麦15的BAC文库,获得1个含有该基因的BAC单克隆,以该BAC单克隆质粒为模板,通过BAC延伸测序克隆了TaLEAsm基因及其启动子序列,并对TaLEAsm序列特征、表达模式和启动子功能进行了初步分析。结果表明,TaLEAsm基因序列仅含有1个105bp的内含子,其开放读码框长675bp,编码224个氨基酸。TaLEAsm含有10个11-氨基酸重复序列,属于第3组LEA蛋白。低温、高盐和渗透胁迫均诱导TaLEAsm基因上调表达,但在根和叶中表达模式不同。在TaLEAsm基因起始密码子上游1 500bp序列中,预测含有14个逆境响应顺式元件。在拟南芥中,TaLEAsm基因启动子能够启动GUS基因表达,渗透胁迫诱导GUS基因明显上调表达。以上结果表明,TaLEAsm为小麦脱水响应基因,其启动子为渗透胁迫诱导启动子。     

Cytoplasmic substitution inSolanum. II. Tuber characteristics of reciprocal backcross progeny

Summary Recurrent backcrosses (BC) were used to introduce nuclear factors ofS. tuberosum L. ssp.tuberosum into the cytoplasm of Andean potatoesS. tuberosum ssp.andigena (Juz. and Buk.) Hawkes andS. phureja Juz. and Buk. Each generation BC was produced in reciprocal directions to test the effect of cytoplasmic substitution on yield. This report analyses tuber number, tuber weight, and tuber length of BC₂ and BC₃ substitution into ssp.andigena cytoplasm and BC₂ and BC₂ substitutions intoS. phureja cytoplasm. Direction of cross had no consistent significant effect on yield components of ssp.andigena substitution lines. InS. phureja reciprocal progenies direction of cross was responsible for significant differences of some reciprocal sets. When there were significant differences the higher yield usually occurred when ssp.tuberosum was the pistillate parent, but in some progenies when ssp.tuberosum was the pistillate parent the yield was significantly lower than in the reciprocals. It is suggested that differences between reciprocals resulted from chromosomally encoded gene action, resulting from maternal and/or paternal effects, rather than cytoplasmic factors. Authorized for publication as paper No. 7494 in the Journal Series of The Pennsylvania Agriculture Experiment Station.     

引发小麦赤霉病和茎基腐病禾谷镰孢菌的生物防治初探

禾谷镰孢菌(Fusarium graminearum)是小麦上的重要病原真菌。通过致病性测定从江苏小麦茎基腐病病害样本分离菌中筛选到了对小麦赤霉病和茎基腐病都有强致病力的F.graminearum菌株GF1117。为了对F.graminearum进行生物防治,利用稀释涂布平板法和平板对峙法从小麦不同生境中分离筛选到35株对GF1117具有明显拮抗效果的细菌菌株,分别在田间和温室进行了小麦赤霉病和茎基腐病的生物防治试验。结果表明,35株拮抗细菌对小麦赤霉病均有一定的防治效果,且在小麦感病品种和中抗品种上对茎基腐病的防效不同;菌株1-8对两种病害的防效都在45%以上。     

基因枪介导的小麦叶片瞬间表达体系的优化及应用

麦类作物的叶片单细胞瞬间表达是一种高效而快速的基因功能验证方法,尤其适用于麦类作物与白粉病菌的互作系统,但由于影响参数较多、参检基因表达频率低而尚未广泛应用。本研究使用绿色荧光蛋白(GFP)基因作为报告基因,对影响表达效率的多个转化参数进行优化,筛选出表达频率最高的参数组,即小麦叶片采用固体保鲜培养基固定,钨粉用量为每枪300μg,质粒DNA用量为每枪750ng,可裂膜氦压为1 350psi,可裂膜与受体膜距离6mm,受体与阻挡网距离6cm,与先前报道的方法相比表达频率有显著提高。应用上述参数在感病小麦品种离体叶片中过量表达一个已知具有抗白粉病功能的簇毛麦SGT1基因,结果表明该基因瞬间表达使互作细胞吸器指数降低,表现为对白粉病菌侵入和吸器形成具有抑制作用,在一定程度上增强了表达细胞对白粉病菌的抗性,使目标基因的抗性功能再次得到印证。本研究还进一步运用该优化体系开展瞬间表达介导的基因沉默(TIGS)实验,将携带抗白粉病基因Pm21的抗病小麦品种南农9918和感病小麦品种扬麦158中的内源SGT1和RAR1分别或同时沉默,结果显示南农9918的叶片表皮与白粉菌互作细胞的吸器指数增高,在一定程度上降低了表达细胞对白粉菌的抗性。而扬麦158中互作细胞的吸器指数较对照变化不显著。说明这两个基因均分别参与了Pm21介导的抗白粉病信号途径,且二者共同作用与白粉病抗性关系更加密切。