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。     

Fusarium head blight and mycotoxin contamination of wheat,a review

Summary An infection of bread wheat by fusarium head blight contaminates the crop with mycotoxins, particularly deoxynivalenol (DON) and nivalenol (NIV). The toxicity and natural occurrence of these mycotoxins in wheat are reviewed. Based on 8 years data of fusarium head blight epidemics of wheat in the Netherlands, DON contamination of the grain was estimated. Fusarium head blight ratings averaged an infection of 1.7% of all spikelets; estimates for DON contamination averaged 0.9 mg kg^–1. Taking a guideline level for DON in uncleaned bread wheat of 2 mg kg^–1, in 1979 and 1982 a wheat crop was produced with estimated DON concentrations above the limit of tolerance. Human and animal exposure to mycotoxins in the Netherlands appears to be small but chronic. The information presented in this paper illustrates the need for an annual evaluation of the crop for fusarium head blight incidence and mycotoxin content, and the necessity of fusarium head blight resistant wheat cultivars.Samenvatting Aaraantasting van tarwe doorFusarium culmorum enFusarium graminearum leidt tot vorming van mycotoxinen in het graan, waarvan deoxynivalenol (DON) en nivalenol (NIV) de belangrijkste toxinen zijn. In dit artikel wordt een overzicht gegeven van de toxicologische aspecten, en het voorkomen van deze toxinen in tarwe. Informatie over DON en NIV in tarwe in West-Europa is schaars. Gebaseerd op gegevens vanFusarium epidemieën in de jaren 1979–1986 wordt een schatting gegeven van de concentratie DON in Nederlandse tarwe. Rekening houdend met de herkomst en verwerking van tarwe, blijken zowel in dierlijk als menselijk voedsel lage concentraties DON chronisch voor te komen. Op basis van een maximaal toelaatbare dagelijkse dosis DON van 3 g kg^–1 lichaamsgewicht is de schatting van de dagelijkse opname van DON in het jaar volgend op de oogst van 1982 net op de grens. Zowel een jaarlijkse inventarisatie vanFusarium aantasting en DON besmetting van het graan, als de ontwikkeling vanFusarium-resistente rassen zijn noodzakelijk.     

不同砧木嫁接网纹甜瓜试验

为预防网纹甜瓜枯萎病等土传病害,以新土佐、灰甘瓜、全能铁甲南瓜,甬砧3号甜瓜为砧木,以当地主栽的拿玻里网纹甜瓜为接穗,进行嫁接试验。结果表明:拿玻里网纹甜瓜嫁接后,植株的抗病性有了显著提高,对枯萎病的防效高达100%,对白粉病的防效也有所提高,综合抗性增强。其中甬砧3号在4个参试砧木品种中,与接穗拿玻里网纹甜瓜的亲和性最好,抗病性提高明显,品质也较自根苗好。     

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     

Whole-Cell Fatty Acid Composition to Characterize and Differentiate Isolates of Rhizoctonia Species Associated with Turfgrass Diseases in Japan

Cellular fatty acids were analyzed to characterize and differentiate 34 isolates of Rhizoctonia species representing binucleate Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB, AG 2-2 LP, R. circinata var. circinata and var. oryzae associated with turfgrass diseases in Japan. Myristic, pentadecanoic, palmitic, palmitoleic, stearic, oleic, linoleic and linolenic acids were consistently present in varying quantities in all isolates. Heptadecanoic and 9-heptadecenoic acids were present in isolates of Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB and AG 2-2 LP but not in isolates of R. circinata var. circinata and var. oryzae. Palmitic, oleic and linoleic acids were the major fatty acids found, constituting 88.30-98.37% of the whole-cell fatty acid content. The remaining fatty acids were present in smaller amounts. Isolates within a single group were closely clustered, whereas isolates from different groups were clearly distinguishable based on average linkage cluster analysis of cellular fatty acids. Principal component analysis, based on all fatty acids detected, confirmed the distinct separation of isolates representing the six groups of Rhizoctonia species obtained from turfgrasses. These results suggested that fatty acid analysis is useful for the characterization and differentiation of isolates of Rhizoctonia species associated with turfgrass diseases. Received 21 May 2001/ Accepted in revised form 28 September 2001     

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     

Toxigenic Fusarium species and Mycotoxins Associated with Head Blight in Small-Grain Cereals in Europe

The Fusarium species predominantly found associated with Fusarium head blight (FHB) in wheat and other small-grain cereals all over Europe are F. graminearum, F. avenaceum and F. culmorum. Among the less frequently encountered species are several others which are less pathogenic or opportunistic, but also toxigenic. These include F. poae, F. cerealis F. equiseti F. sporotrichioides F. tricinctum and, to a lesser extent, F. acuminatum F. subglutinans F. solani F. oxysporum F. verticillioides F. semitectum and F. proliferatum. The species profile of FHB is due to several factors, primarily climatic conditions, particularly rain and the temperature at flowering stage, but also agronomic factors, such as soil cultivation, nitrogen fertilization, fungicides, crop rotation, and host genotype. The most frequently encountered Fusarium mycotoxins in FHB in Europe has proved to be deoxynivalenol and zearalenone produced by F. graminearum and F. culmorum with the former more common in southern (warmer) and the latter in northern (colder) European areas. Nivalenol was usually found associated with deoxynivalenol and its derivatives (mono-acetyldeoxynivalenols), together with fusarenone-X, formed by F. graminearum F. cerealis F. culmorum and, in northern areas, by F. poae. Moreover, from central to northern European countries, moniliformin has been consistently reported, as a consequence of the widespread distribution of F. avenaceum whereas the occurrence of T-2 toxin derivatives, such as T-2 toxin and HT-2 toxin, and diacetoxyscirpenol have been recorded in conjunction with sporadic epidemics of F. sporotrichioides and F. poae. Finally, beauvericin and various enniatins have recently been found in Finnish wheat colonized by F.avenaceum and F. poae.     

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.     

镧素对镰刀菌Fusarium solani及其致病酶的影响

采用琼脂平板生长速率法及液体培养基培养测定了La对镰刀菌Fusarium solani的抑制作用和毒力,并测定了其对病菌胞外的果胶酶、蛋白酶和纤维素酶等几种致病酶活性的影响。结果表明,随着La2O3浓度升高,对病菌菌丝生长的抑制作用增强,对病菌的EC50和EC95分别为278.2和552.0 mg/L;在一定浓度范围内,La提高了单位量菌丝所产生3种致病酶的活性,但由于菌丝生长受到抑制,除蛋白酶外,病菌胞外致病酶果胶酶和纤维素酶的总量或总活性受到了抑制,降低了病菌的致病力。     

几种除草剂对水稻纹枯病菌的影响

研究了丁草胺、环庚草醚、草甘膦、苄嘧磺隆、吡嘧磺隆和环丙嘧磺隆6种除草剂对水稻纹枯病菌菌丝生长和菌核形成的影响。结果表明,在一定浓度范围内,6种除草剂均能抑制菌丝生长,减少菌核形成数量,且浓度越高,抑制能力越强,但在较高浓度范围内,除草剂可增加菌核体积;吡嘧磺隆在5μg/ml、环丙嘧磺隆在10μg/ml时可增加菌核形成数量;在含除草剂培养基上产生的菌核都可萌发。