地膜覆盖对棉枯萎病发生的影响

地膜覆盖显著降低了棉花枯萎病的发病率与病情指数，极显著地提高了棉花的产量。     

Fusarium oxysporum对苗期大豆根部的致病性和侵染规律

Fusarium oxysporum对苗期大豆具有较强的致病作用。病原菌自伤口或直接侵入大豆幼苗根部的皮层组织,随着病原菌的侵入和扩展,细胞出现坏死,组织发生崩解,根部组织表现红褐色病斑。环境因素对病原菌的侵染时期和在大豆体内潜育时间的长短有着明显的影响。侵染时期主要受病原菌侵入前自身所处状态和寄主的影响,侵入后潜育时间的长短则受植株状态的影响。土壤环境条件直接影响着病原菌的侵入和寄主的抗病性,间接影响着病原菌在大豆植株体内的扩展和病症的表现。     

梨菇的化学成分分析

对江西赣南北部林区的野生裂菇进行了化学成分分析，结果表明，它含金属元素15种、粗蛋白含量达27．52％、氨基酸含量达23．98％，是一种很优秀的野生食用菌。     

棉花枯、黄萎病菌营养亲和性研究进展

介绍了棉花枯、黄萎病菌营养亲和性研究方法和营养体亲和群研究,并着重总结了利用营养亲和群结合DNA多态性技术,研究尖孢镰刀菌(FusariumoxysporumSchlechtend:Fr)专化型、生理小种、亲和群之间的关系,以及棉花黄萎病菌(VerticilliumdahliaeKleb.)亲和群与致病型关系的研究进展。     

Physiological Races and Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae Isolated from Crisphead Lettuce in Japan

One hundred and sixteen isolates of Fusarium oxysporum f. sp. lactucae obtained from 85 fields in three crisphead lettuce-producing areas in Nagano Prefecture, Japan were typed for races using differential cultivars Patriot, Banchu Red Fire and Costa Rica No. 4. They were also grouped into vegetative compatibility groups (VCGs) using complementation tests with nitrate non-utilizing (nit) mutants. Two California strains reported as F. oxysporum f. sp. lactucum, a type culture of F. oxysporum f. sp. lactucae, and 28 avirulent isolates of F. oxysporum obtained from crisphead lettuce were included for comparison. Among Nagano isolates, 66 isolates were identified as race 1, and 50 as race 2. Race 1 strains derived from Shiojiri and Komoro cities and race 2 from Kawakami village and Komoro city. All isolates of race 2 were biotin auxotrophs, and the race could be distinguished based on its requirement for biotin on minimal nitrate agar medium (MM). Pathogenic isolates were classified into two VCGs and three heterokaryon self-incompatible isolates. Strong correlations were found between race and VCG. All the race 1 strains were assigned to VCG 1 except self-incompatible isolates, and all the race 2 strains to VCG 2. The 28 avirulent isolates of F. oxysporum were incompatible with VCG 1 and VCG 2. California strains was vegetatively compatible with VCG 1, and they were assigned to race 1. Based on vegetative compatibility, these two races of F. oxysporum f. sp. lactucae may be genetically distinct, and F. oxysporum f. sp. lactucae race 1 is identical to F. oxysporum f. sp. lactucum. Received 7 May 2002/ Accepted in revised form 6 September 2002     

Aromatic Substances Inhibiting Wheat Powdery Mildew Produced by a Fungus Detected with a New Screening Method for Phylloplane Fungi

Microorganisms isolated from wheat leaf surfaces were screened for inhibition of wheat powdery mildew. A new screening method, in which wheat leaves were inoculated with Blumeria graminis f. sp. tritici and incubated with the cultured microorganisms under non-contact conditions, was developed in the present study. Using this method, 10 phylloplane fungi that inhibited wheat powdery mildew were selected from 408 microorganisms isolated from wheat leaf surfaces. Among these 10 strains, a fungus designated as Kyu-W63 had an especially strong inhibitory effect. Kyu-W63 produced white colonies without spores when cultivated on PDA. Kyu-W63 had a strong aromatic odor when being cultured. Wheat powdery mildew was suppressed even though a membrane filter with a pore size of 0.45 μm was placed between the mycelial colony and wheat leaf segment. However, when activated charcoal was introduced, Kyu-W63 did not inhibit growth of B. graminis. It was presumed that volatile substances were involved in the inhibitory effect of Kyu-W63. GC-MS analysis was used to identify two substances produced by Kyu-W63 with molecular weights of 164 and 166. Kyu-W63 also inhibited the in vitro growth of four plant pathogenic fungi other than B. graminis. Received 19 September 2001/ Accepted in revised form 7 February 2002     

Induction of an antioxidant enzyme system and other oxidative stress markers associated with compatible and incompatible interactions between chickpea (Cicer arietinum L.) and Fusarium oxysporum f. sp.ciceris

To ascertain if active oxygen species play a role in fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceris, the degree of lipid peroxidation (malondialdehyde formation) and the activity levels of diamine oxidase (DAO), an apoplastic H₂O₂-forming oxidase, and several antioxidant enzymes, namely ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guaiacol-dependent peroxidase (GPX) and superoxide dismutase (SOD), were determined spectrophotometrically in roots and stems of ‘WR315’ (resistant) and ‘JG62’ (susceptible) chickpea cultivars inoculated with the highly virulent race 5 of the pathogen. Moreover, APX, CAT, GPX and SOD were also analysed in roots and stems by gel electrophoresis and activity staining; and the protein levels of APX and SOD in roots were determined by Western blotting. In roots, infection by the pathogen increased lipid peroxidation and CAT and SOD activities, although such responses occurred earlier in the incompatible compared with the compatible interactions. APX, GPX and GR activities were also increased in infected roots, but only in the compatible interaction. In stems, infection by the pathogen increased lipid peroxidation and APX, CAT, SOD and GPX activities only in the compatible interaction, and DAO activity only in the incompatible one. In general, electrophoregrams agreed with the activity levels determined spectrophotometrically and did not reveal any differences in isoenzyme patterns between cultivars or between infected and non-infected plants. Further, Western blots revealed an increase in the root protein levels of APX in the compatible interaction and in those of SOD in both compatible and incompatible interactions. In conclusion, whereas enhanced DAO activity in stems, and earlier increases in lipid peroxidation and CAT and SOD activities in roots, can be associated with resistance to fusarium wilt in chickpea, the induction of the latter three parameters in roots and stems along with that of APX, GR (only in roots) and GPX (only in stems) activities are rather more associated with the establishment of the compatible interaction.     

细胞骨架解聚药物对小麦与叶锈菌互作诱发的细胞过敏性反应的影响

 小麦(Triticum aestivum)品种洛夫林10和叶锈菌小种366组成不亲和组合,小麦叶片发生过敏性坏死反应(HR)是小麦抵抗叶锈菌侵染的重要因素。在接种前给小麦叶片分别预注射微管解聚药物磺草硝(oryzalin)和微丝解聚药物细胞松弛素D (cytochalasin D,CD),结果表明2种药物注射使得寄主因叶锈菌侵染诱导的细胞过敏性坏死数目明显减少,并且注射药物的浓度越大,寄主细胞发生HR的数量越少。说明肌动蛋白和微管蛋白的聚合状态是诱发小麦叶片发生HR防卫反应所必需的,细胞骨架在小麦抵抗叶锈菌侵染过程中可能起着重要作用。     

Physiologic races ofFusarium oxysporum f.sp.melonis in the southeastern anatolia region of turkey and varietal reactions to races of the pathogen

Thirty-four isolates ofFusarium oxysporum f.sp.melonis (F.o.m.) obtained from 205 fields in melon-producing areas in the southeastern Anatolia Region of Turkey were identified on the basis of colony morphology and pathogenicity by the root dip method. In this region the mean prevalence of wilt disease was 88.1% and the mean incidence of disease was 47.5%. Physiologic races 0, 1, 2, and 1,2 of the pathogen were determined by their reactions on differential melon cultivars ‘Charentais T,’ ‘Isoblon’, ‘Isovac’ and ‘Margot’ in the greenhouse. Race 1,2, representating 58.8% (20/34) of all isolates, was widely distributed. Of the other pathogenic isolates, eight were identified as race 0, five as race 1, and one as race 2. This is the first report of physiologic races ofF.o.m. in Turkey. Of 44 melon cultivars tested in the greenhouse for resistance toF.o.m. races, 36 were found to be moderately resistant to race 0, 17 were susceptible to race 1,2, 34.1% were highly resistant to race 1, and 52.2% had moderate resistance to race 2. http://www.phytoparasitica.org posting July 16, 2002.     

非自然越夏区小麦白粉病模拟鉴定病圃

作者于1990～1995年根据陕西省关中麦区小麦白粉病侵染循环特点,人工模拟自然发病条件,在非自然越夏区杨陵(省农科院试验地)成功地建立起白粉病菌可周年存活,且秋、春季均能充分诱发感染的混合菌系病圃,宜对小麦种质材料进行全生育期抗白粉病鉴定。利用该病圃已对陕西省1000余份小麦品种(系)及部分国内外抗源亲本材料做了抗病性鉴定和利用评价。