稻梨孢菌与其他寄主梨孢菌在水稻植株上的交互作用

作者研究了1个稻梨孢菌株与4个稻以外寄主梨孢菌株在混合接种和间隔接种条件下,在水稻植株上的交互作用。结果表明:弱致病菌与强致病菌间交互作用较强,非致病菌与强致病菌间较弱。弱致病菌可明显降低强致病菌的致病性,非致病菌对强致病菌的作用,多数组合表现为减轻病害,但有少数组合表现为促进发病。弱致病菌先接种;2天后接种强致病菌,比两者混合接种具有更强烈的互作效应,病斑数减少达35.7％—38.1％。先接种菌的孢子浓度对后接种菌的致病性也有影响。     

稻梨孢菌与其他寄主梨孢菌在水稻植株上的交互作用

作者研究了1个稻梨孢菌株与4个稻以外寄主梨孢菌株在混合接种和间隔接种条件下,在水稻植株上的交互作用。结果表明:弱致病菌与强致病菌间交互作用较强,非致病菌与强致病菌间较弱。弱致病菌可明显降低强致病菌的致病性,非致病菌对强致病菌的作用,多数组合表现为减轻病害,但有少数组合表现为促进发病。弱致病菌先接种;2天后接种强致病菌,比两者混合接种具有更强烈的互作效应,病斑数减少达35.7%-38.1%。先接种菌的孢子浓度对后接种菌的致病性也有影响。     

用RAPD研究我国杨生褐盘二孢菌的群体分化

 杨生褐盘二孢菌(Marssonina brunnea)是引起我国杨树黑斑病的最主要病原。病原菌的形态学和致病性分析已经证明这个种有分化现象。本研究从我国不同地区不同寄主上收集了42个杨生褐盘二孢菌菌株,用随机扩增多态性DNA (RAPD)研究了它们之间的遗传多样性。聚类分析根据80%的相似性把42个菌株分成3个组(A、B和AB组)。A组中包含有4个分离自毛白杨的菌株;B组中含37个自青杨派和黑杨派分离的菌株;AB组中仅含有1个分离自响叶杨的菌株。推断AB组菌株可能是A组菌株向B组菌株进化的一个过渡类型。     

稻区杂草上的梨孢菌与稻瘟病发生的关系

 新发现的稻曲病菌白化菌株其分生孢子座白色,厚垣孢子表面光滑,大小为3.5-6.0×3.5-6.8μm。在麦芽糖-稻芽浸渍液中可产生较多的分生孢子。pH值为6时生长最好。普通培养基中加入几种供试碳源和氮源均有利于菌落生长,以蔗糖为碳源,浓度为2%或以L-天门冬酰胺为氮源浓度为0.2%~0.3%时时其菌落生长有促进作用。培养过程中可产生对稻种萌发有抑制作用的毒素,而固体培养时产毒能力高于液体培养。白化菌株回接到水稻上可重新产生白色稻曲球。该菌和稻曲病菌的酯酶同功酶和RAPD扩增谱带明显不同。可见白化菌株具有独立于稻曲病菌的新的分类地位。     

应用DNA标记定位水稻的抗稻瘟病基因

 从水稻分子遗传图谱选取177个RFLP标记,比较以红脚占为抗源,感病品种IR24为轮回亲本所构建的近等基因对K80R和K79S之间的多态性表现。发现了一些可能与稻瘟病抗性基因连锁的阳性标记。在(K80R×K79S)的F₂群体中,经稻瘟病菌ZB₁小种接种,110株为抗病,33株为感病,用总共10个阳性标记与F₂群体中每个单株的DNA杂交,发现抗病基因与第12染色体上的标记RG81、RG869和RZ397共分离;检测F₃株系的抗病性分离情况,确定F₂植株的抗病性基因型,计算出抗病基因与分子标记的遗传距离,将该基因定位在第12连锁群上。应用近等基因池DNA和随机引物,经PCR扩增和共分离分析,建立了二个RAPD片段与抗病基因紧密连锁。     

我国梨和部分国外梨果实上链格孢菌的鉴定研究

本文从链格孢的产孢表型、分生孢子特征和分子生物学方面研究了从河北鸭梨、新疆库尔勒香梨、美国和日本以及智利的梨上分离的链格孢菌的种类.经对115支Alternaria菌株的形态学鉴定,共确定了3个种,即Alternaria alternata、A.tenuissima和A.infectoria.ITS系统发育分析研究表明,Alternaria大孢子种彼此间及大孢子种与小孢子种间已发生明显分化,可以根据ITS序列差异明确区分.而供试的多数小孢子种在ITS序列上差异很小,因而不能根据ITS序列差异来区分.     

玉米穗腐病和茎基腐病镰孢菌间相关性的RAPD分析

 利用随机扩增多态性DNA (RAPD)技术对玉米穗腐病和茎基腐病镰孢菌之间的相互关系进行了研究,证实了引起2种病害的串珠镰孢菌同源性很高,在遗传上具有较高的相似性,病菌不易受地域或环境和寄生部位选择作用的影响,同一类型的串珠镰孢菌可以是穗腐病和茎腐病的共同病原菌。禾谷镰孢菌间的遗传变异性很强,易受地域、环境和寄生部位选择作用的影响,出现明显的分化现象,穗腐病和茎基腐病可以由同一禾谷镰孢菌分化类型侵染所致,也可由不同分化类型侵染所致。     

稻瘟菌对水稻品种梅雨明的无毒性的遗传分析和分子标记

 将交配型为a、并对水稻品种梅雨明不致病的稻瘟菌菌株S1522与对该品种致病的、交配型为A的稻瘟菌菌株P131和S159杂交,分别获得了24和56个单子囊孢子后代。致病性测定结果表明:这些后代菌株在梅雨明上的致病个体与不致病个体的比例近等于1:1。由此推测:稻瘟菌对水稻品种梅雨明的无毒性是由1个基因控制的。进一步通过RAPD比较了致病后代与不致病后代的DNA多态型,获得了1个与该无毒基因连锁的、长度为1000 bp的RAPD标记,两者间的遗传距离为3.7cM。     

河南省首次发现梨孢镰刀菌引起的小麦赤霉病

2015年从河南省田间小麦赤霉病病穗上分离得到一种生长速度较慢的镰刀菌, 通过形态学和分子鉴定明确其分类地位, 通过田间单小花滴注法和喷雾法接种测定其致病力, 并通过高效液相色谱串联质谱分析对麦穗中的毒素种类进行测定, 明确其产毒特征?结果表明:分离得到的8个菌株均为梨孢镰刀菌, 在马铃薯葡萄糖琼脂(PDA)培养基上为白色菌落, 菌落底部产生少量红色色素, 平均生长速度为13.3 mm/d; 小型分生孢子为椭球形葡萄状, 平均大小为7.1 μm×5.8 μm, 未见大型分生孢子和厚垣孢子; 致病力弱, 且不侵染穗轴, 单小花滴注法接种条件下平均病级为0.1, 喷雾法接种条件下平均病小穗率为6.5%; 供试的8个镰刀菌菌株均不产生T-2和HT-2毒素, 均产生雪腐镰刀菌烯醇(NIV)毒素, NIV毒素含量水平为371.74~5 282.80 μg/kg, 其中3个菌株产生少量脱氧雪腐镰刀菌烯醇(DON)毒素(86.13~227.22 μg/kg)?     

尖孢镰刀菌的遗传多态性

 尖孢镰刀菌是重要的植物维管束病原真菌。近年来,有关该菌的遗传多态性研究报道很多,本文着重综述了利用营养体亲和群、DNA多态性技术研究尖孢镰刀菌专化型、小种及其相互关系等方面的进展,同时介绍了对棉花枯萎病菌、瓜类枯萎病菌及尖孢镰刀菌小种起源等的研究概况。     

Phylogenetic Relationships of Xylella fastidiosa Strains Isolated from Landscape Ornamentals in Southern California

ABSTRACT Xylella fastidiosa is an insect-borne, xylem-limited pathogenic bacterium that has been associated with a rise in incidence of diseased landscape ornamentals in southern California. The objective of this study was to genetically characterize strains isolated from ornamental hosts to understand their distribution and identity. Strains of X. fastidiosa isolated from ornamentals were characterized using a multiprimer polymerase chain reaction (PCR) system, random amplified polymorphic DNA (RAPD)-PCR, and sequence analysis of the 16S-23S rDNA intergenic spacer region (ISR). Based on RAPD-PCR and 16S-23S rDNA ISR, strains isolated from daylily, jacaranda, and magnolia clustered with members of X. fastidiosa subsp. sandyi and caused oleander leaf scorch but not Pierce's disease symptoms in glasshouse assays on oleander and grape, respectively. This demonstrated both that our groupings based on genetic characterization were valid and that strains of X. fastidiosa subsp. sandyi are present in hosts other than oleander. Strains isolated from Spanish broom, cherry, and one strain isolated from western redbud clustered with X. fastidiosa subsp. fastidiosa members. Strains isolated from purple-leafed plum, olive, peach, plum, sweetgum, maidenhair tree, crape myrtle, and another western redbud strain clustered with members of X. fastidiosa subsp. multiplex. All strains isolated from mulberry and one from heavenly bamboo formed a separate cluster that has not yet been defined as a subspecies.     

二氯喹啉草酮对不同龄期稻田主要杂草的生物活性

采用室内整株生测法测定新型除草化合物二氯喹啉草酮对稻田主要杂草光头稗(Echinochloa colonum)、硬稃稗(Echinochloa glabrescens)、无芒稗(Echinochloa crusgalli var.mitis)、西来稗(Echinochloa crusgalli var.zelayensis)、千金子(Leptochloa chinensis)、马唐(Digitaria sanguinalis)、鳢肠(Eclipta prostrata)、碎米莎草(Cyperus iria)、异型莎草(Cyperus difformis)的生物活性。结果表明:二氯喹啉草酮对播后苗前、2~3叶期、4~5叶期的光头稗、硬稃稗、无芒稗、西来稗、马唐、鳢肠、异型莎草ED90在150~570 g a.i./hm2间;不同叶期的千金子对二氯喹啉草酮敏感性低,二氯喹啉草酮对其ED90均高于735 g a.i./hm~2。     

几种除草剂对稻田杂草的防除效果

选择田草绝、精克草星、稻草隆、草克净、巧手等进行田间试验，结果表明，5种药剂均具有良好的防效和安全性。     

不同除草药膜防除棉田杂草效果

为了加快推进江苏省棉田无草害工程的顺利实施,笔者１９９８年开展了不同除草药膜在沿海棉田应用对杂草的防除效果及产量效应的研究工作,旨在为大面积推广应用和作为棉花双膜栽培的一项配套新技术提供科学依据。１材料与方法试验设喷涂法生产杜尔药膜、重新造粒法生产杜...     

苄嘧·丙草胺等防除旱直播稻田杂草的效果

30%苄嘧.丙草胺等在播后芽前进行土壤封闭处理防除旱直播稻田杂草安全性较好。30%苄嘧.丙草胺适宜用量为1800-2 250 g/hm2,50%苄.戊.异丙隆适宜用量为1 500-1 800 g/hm2,基本可以一次用药控制旱直播稻田整季杂草危害。     

Pyricularia grisea Isolates Causing Gray Leaf Spot on Perennial Ryegrass (Lolium perenne) in the United States: Relationship to P. grisea Isolates from Other Host Plants

ABSTRACT Gray leaf spot of perennial ryegrass (prg) (Lolium perenne), caused by the fungus Pyricularia grisea (teleomorph = Magnaporthe grisea), has rapidly become the most destructive of all turf grass diseases in the United States. Fungal isolates from infected prg were analyzed with several molecular markers to investigate their relationship to P. grisea strains found on other hosts. All of the molecular markers used in this study revealed that isolates from prg are very distantly related to those found on crabgrass. Fingerprinting with MGR586 (Pot3) revealed zero to three copies of this transposon in the prg pathogens, distinguishing them from isolates pathogenic to rice, which typically have more than 50 copies of this element. RETRO5, a newly identified retroelement in P. grisea, was present at a copy number of >50 in isolates from rice and Setaria spp. but only six to eight copies were found in the isolates from prg. The MAGGY retrotransposon was unevenly distributed in the prg pathogens, with some isolates lacking this element, some possessing six to eight copies, and others having 10 to 30 copies. These results indicated that the P. grisea isolates causing gray leaf spot are distinct from those found on crabgrass, rice, or Setaria spp. This conclusion was supported by an unweighted pair-group method with arithmetic average cluster analysis of single-copy restriction fragment length polymorphism haplo-types. Fingerprints obtained with probes from the Pot2 and MGR583 transposons revealed that the prg pathogens are very closely related to isolates from tall fescue, and that they share similarity with isolates from wheat. However, the wheat pathogens had fewer copies of these elements than those found on prg. Therefore, I conclude that P. grisea isolates commonly found on other host plant species did not cause gray leaf spot epidemics on prg. Instead, the disease appears to be caused by a P. grisea population that is specific to prg and tall fescue.     

Genetic Analysis of a Pathogenic Erwinia sp. Isolated from Pear in Japan

ABSTRACT Four Erwinia strains, originally isolated in Japan from pear trees with bacterial shoot blight symptoms, were analyzed to determine their genetic relationship with Erwinia amylovora and E. pyrifoliae. When genomes were characterized with amplified fragment length polymorphism markers and by comparative groEL sequence analysis, the Japanese Erwinia sp. and South Korean E. pyrifoliae strains were placed in the same group, which was phylogenetically distinct from a group of 15 strains of E. amylovora. Sequencing of the 29,593-bp plasmid pEJ30 from Erwinia strain Ejp556 revealed that this plasmid was nearly identical to plasmid pEP36 from E. pyrifoliae and was closely related to the nontransferable ubiquitous plasmid pEA29 from E. amylovora. Twenty-one presumptive genes and their order in pEP36 were highly conserved in pEJ30; however, transposon Tn5394, which was present in pEP36, was not found in pEJ30. Short-sequence DNA repeats were conserved between pEJ30 and pEP36, and were different from short-sequence repeats in pEA29. Despite base-pair mismatches, primer pairs used in pEA29 polymerase chain reaction assays for E. amylovora amplified plasmid DNA from the Japanese Erwinia Ejp556 and Ejp562. Like E. pyrifoliae and a few strains of E. amylovora, Japanese Erwinia Ejp617 contained plasmids related to E. pyrifoliae ColE1-related plasmid pEP2.6. Based on these genetic analyses, we conclude that the Erwinia pathogen of pear in Japan is closely related to E. pyrifoliae and that both of these pathogens are demonstrably distinct from E. amylovora.     

Phylogenetic relationships of Fusarium oxysporum f. sp. melonis in Iran

Fusarium wilt of melon caused by Fusarium oxysporum f. sp. melonis is a destructive fungal disease in melon growing regions. Isolates of F. oxysporum obtained from six major melon producing provinces in Iran, from melons and other hosts, were characterized based on pathogenicity to melon, vegetative compatibility groups (VCGs) and nuclear ribosomal DNA intergenic spacer (IGS) sequencing. Thirty-four of 41 isolates from Iran in this study were identified as race 1,2 which belonged to either VCG 0134 or an unassigned VCG, which based on IGS sequencing grouped with the VCG 0135 tester isolate. The seven remaining isolates were identified as nonpathogenic to melon belonging to two undescribed VCGs. Based on sequence analyses of the IGS region of Iranian and foreign isolates, nine lineages were identified, each including one VCG. The separation of VCGs into distinct lineages based on IGS sequences is mostly consistent with Repetitive extragenic palindromic PCR (Rep-PCR) results. Exceptions are VCGs 0130 and 0131, which could be differentiated with IGS sequences, but not with Rep-PCR. Different races from the USA, France and Iran associated with VCG 0134 grouped into one IGS lineage but could be differentiated with Rep-PCR, suggesting that this VCG is more diverse than previously thought. Given the long history of melon cultivation in Iran and the Rep-PCR diversity of isolates belonging to this VCG, it could be speculated that VCG 0134 perhaps evolved in Iran.     

40%氰津·乙悬乳剂防除棉花田杂草试验

田间试验表明40%氰津·乙悬乳剂对棉花田杂草具有良好的控制效果,200～250mL/667m2用药后50d对杂草株防效94%以上,鲜重防效94%以上。