Vegetative compatibility groups and sexual reproduction among Spanish Monilinia fructicola isolates obtained from peach and nectarine orchards,but not Monilinia laxa

The frequency of occurrence of Monilinia fructicola in the Ebro Valley, Spain has increased since its first appearance in 2006, and M. fructicola has displaced Monilinia laxa, the native species which is the main cause of brown rot in peaches in this valley. In order to determine the characteristics that may be related to the displacement, we studied the capacity to generate new genotypic combinations of M. fructicola under laboratory conditions. The morphology and parasitic ability from ten field isolates of M. fructicola and M. laxa collected from three different orchards in the valley, and sampling from five different lesions were studied. Nitrate-non-utilising (nit) mutants were generated in order to test the isolates for vegetative compatibility which was done by assessing their colony growth when cultured singly or in pairs on media that contained different nitrogen sources. For the M. fructicola isolates, five vegetative compatibility groups (VCGs) were identified using the nit mutants and six VCGs were identified when they were grown on potato dextrose agar dishes. In all instances, the vegetatively compatible M. fructicola isolates came mainly from the same orchard. Only one VCG displays the same morphological and competition characteristics. No VCGs were identified among the M. laxa isolates. We did not find any apothecia of M. laxa and M. fructicola isolates in the soil of the three orchards, but we were able to produce apothecia of M. fructicola in the laboratory. Our finding of sexual reproduction and VCGs in the M. fructicola isolates suggests that the genetic variability of M. fructicola could be maintained by sexual and/or parasexual recombination.     

美洲黑杨不同无性系对分月扇舟蛾幼虫的抗性及相关机理

为了选育出在生产上具有推广价值的美洲黑杨Populus deltoides优良抗虫品系,本研究以分月扇舟蛾Clostera anastomosis 3龄幼虫为材料,以I-72杨为对照评价和分析了18个美洲黑杨无性系在实验室条件（28±1℃,RH 70%,16L∶8D）下的抗虫性,通过选择性和非选择性取食实验筛选出了11个具有较强抗性的无性系; 测定了美洲黑杨主要营养物质和次生代谢物质含量,研究了不同无性系对分月扇舟蛾体内保护酶和消化酶活性及对该虫生长发育和食物利用的影响。结果表明：美洲黑杨不同无性系抗性的大小与它们叶片中总酚含量呈明显正相关趋势; 抗性水平不同的无性系对分月扇舟蛾幼虫的生长发育和食物利用有不同的影响,表现在幼虫体重、每日体重增加量、相对生长率、近似消化率、食物利用率和食物转化率等主要生长发育指标的变化上,同时对分月扇舟蛾幼虫取食量和排粪量亦有不同的影响。结果说明,分月扇舟蛾对次生代谢物质的反应更为敏感,抗性无性系对分月扇舟蛾幼虫体内SOD和CAT酶活性有明显的激活作用。     

小核菌中dsRN 的存在、位置及其生防作用

ScleortiumcepivorumBerk.是引起洋葱白腐病的病原真菌,大部分测试的菌株含有dsRNA片段,这些dsRNA片段被称为真菌病毒。经琼脂糖凝胶电泳分析,在不同分离株之间或同一分离株不同提取物之间dsRNA带的数量和位置有很大的变化。ScQ-4菌株菌丝生长缓慢,致病力明显低于其他菌株。采用蔗糖密度梯度离心法证实和确定ScQ-4菌株中dsRNA片段所处的亚细胞位置,结果表明这些dsRNA片段与其寄主线粒体共同纯化,因此它们可能存在于寄主线粒体中,属于线粒体病毒。在营养相容性菌株之间这些dsRNA片段可通过菌丝融合进行传播,获得dsRNA片段的受体菌株的致病力明显降低,这对SclerotiumcepivorumBer.k进行生物防治提供了可能性。     

Characterization and Sensitivity to Fungicides of Rhizoctonia spp. Recovered from Potato Plants in Bolu,Turkey

Isolates of Rhizoctonia spp. associated with stem canker and black scurf disease of potato were examined for their anastomosis group, sequence variations in the ITS‐5.8S rDNA region, pathogenicity and sensitivity to fungicides. A total of 92 isolates were obtained from diseased tuber, stolon and sprouts of the potato plants, collected from five districts of Bolu province, Turkey. Based on the anastomosis group and the similarity of the nucleotide sequence of the ITS‐5.8S rDNA, most of the isolates (81.5%) were identified as AG 3 PT. Other isolates belonged to AG 2‐1 (1.08%), AG 2‐2 IV (1.08%), AG 4 HG II (8.07%), AG 5 (2.17%), binucleate Rhizoctonia AG A (1.08%) and AG K (4.35%). Pathogenicity tests showed that isolates of AG 3 PT, AG 4 HG II and AG 5 caused similar degrees of disease severity on 45‐day‐old potato seedlings, whereas AG 2‐1 was moderately virulent. AG 2‐2 IV and binucleate Rhizoctonia spp. were weakly pathogenic or non‐pathogenic on potato seedlings. In this study, anastomosis groups of Rhizoctonia spp. isolates associated with potato in Turkey were characterized for the first time using molecular techniques and classified at the level of subgroups. Furthermore, the effect of selected fungicides was evaluated on disease development caused by soil‐borne inoculums of different anastomosis groups (AGs). Flutolanil and Bacillus subtilis QST 713 were found to be most effective against the Rhizoctonia isolates tested. These results revealed significant differences among the fungicides on disease development resulted from the different AGs.     

黄淮海地区夏玉米纹枯病菌的融合群鉴定

从黄淮海地区采集玉米纹枯病标样250余份,分离得到176个丝核菌菌株。融合群测定及5.8SrDNA-ITS区序列分析结果表明,这些菌株分别属于多核丝核菌的AG1-IA、AG1-IB、AG4-HG-I、AG-5、WAG-Z融合群及双核丝核菌的AG-A、AG-Ba融合群。其中AG1-IA是优势融合群,占分离菌株总数的64.20%,其次是AG-Ba,占12.50%,再依次分别是WAG-Z(10.23%)、AGI-IB(5.11%)、AG-4-HG-I(3.98%)、AG-5(2.27%)和AG-A(1.70%)。其中AG-Ba融合群是国内首次在玉米上分离得到。从各融合群中选取代表性的菌株进行5.8S rDNA-ITS区序列分析结果表明,隶属不同融合群或亚群的菌株其5.8S rDNA-ITS区序列存在较大的差异,而相同融合群(或亚群)不同菌株之间其序列的一致性可高达97%-100%。     

美洲黑杨不同无性系对分月扇舟蛾幼虫的抗性

以分月扇舟蛾Clostera anastomosis(L.)为材料,以I-72杨为对照,研究南京林业大学新近引进的18个美洲黑杨(Populus deltoides L.)无性系在实验室条件下的抗虫性,筛选出11个具有较强抗性的无性系,并分析不同无性系的抗性与其叶片中主要营养物质和次生代谢物质含量的关系,初步解释其抗性机理。其研究结果为今后进行林间试验,选育出在生产上具有推广价值的美洲黑杨优良抗虫品系提供科学依据。     

虫害诱导黑杨对分月扇舟蛾生长发育的影响

在实验室条件下,通过人工饲养研究了虫害处理的69杨和895杨对分月扇舟蛾Clostera anastomosis幼虫、蛹及成虫的生长发育的影响。结果表明:虫害处理的叶片对分月扇舟蛾幼虫表现为驱避作用;取食虫害处理的叶片,使得幼虫的发育历期延长,死亡率增加,对食物的利用和转化效率下降;蛹重减轻,蛹期延长;成虫的羽化率降低,产卵量减少。说明昆虫取食危害能够诱导杨树对分月扇舟蛾产生抗虫性。     

中国东北地区玉米纹枯病菌的融合群鉴定

自东北三省采集玉米纹枯病标本300余份,分离获得286个丝核菌菌株。融合群测定及5.8S rDNA-ITS区序列分析结果表明,这些菌株分别属于多核丝核菌的AG1-IA、AG1-IB、AG1-IC、AG4-HG-I、AG4-HG-III、AG-5、WAG-Z群及双核丝核菌的AG-Ba群。其中AG1-IA是优势致病群,占分离菌株总数的38.46%,其次是WAG-Z和AG-5群,分别占26.92%及24.83%。AG4-HG-III群菌株是国内首次从罹病玉米植株上分离得到。自各融合群中选取代表性的菌株进行5.8     

降落伞式缝合在肠道吻合术中的应用

目的:通过胆肠吻合缝合技术的改进,减少并发症的发生。方法:对52例肠道吻合手术采用降落伞式缝合。结果:降落伞式胆肠吻合时间平均20 min,明显缩短了手术时间,全部病例均未出现胆肠吻合漏,无死亡病例。结论:降落伞式胆肠吻合术具有操作简便、省时、并发症少等特点。