我国花生白绢病菌致病力差异

为了解我国花生白绢病病原菌株的致病力差异,本文对分离自不同地域的39个代表菌株进行了田间、室内(离体主茎、侧枝和叶片)接种试验,结果表明所有菌株均对花生具有致病性,但致病力存在显著差异。田间接种花生植株与室内接种离体主茎、侧枝和叶片的病情指数呈显著正相关,同一菌丝融合群的菌株对花生的致病力存在差异。所揭示致病力差异,为花生白绢病的防控、品种合理布局提供了理论基础和技术支持。

The quantity of OA and activity of cellulase and polygalacturonase are involved in variation of virulence in Sclerotium rolfsii

In order to understand the pathogenic mechanisms of Sclerotium rolfsii on peanut and to analyze the variation of virulence in S.rolfsii strains,the highly virulent strain(ZY2)and weakly virulent strain(GP3-1)were investigated under both in vivo and in vitro conditions.The results indicated that S.rolfsii directly infected peanut by producing infection cushions.ZY2 formed infection cushions earlier than GP3-1,and ZY2 produced a greater number of infection cushions compare to GP3-1.Both strains could utilize cellulose,xylose,or polygalacturonic acid in the Czapek medium.The activities of cellulase(CL)and polygalacturonase(PG)in the inoculated peanut stems increased significantly at 9 h after inoculation.The activities of CL and PG produced by ZY2 in the inoculated stems were significantly higher than that produced by GP3-1.Both strains could produce oxalic acid(OA),and the content of OA produced by ZY2 in the inoculated stems was higher than that produced by GP3-1.In summary,it suggested that S.rolfsii destroyed peanut cells through physical and biochemical factors by secreting a large amount of OA,CL and PG during the formation of infection cushions.The difference in OA content,activity of CL and PG produced by highly and weakly virulent strains played important roles in variation of virulence.

花生品系对白绢病的抗性评价及产量损失研究

选取中国农业科学院油料作物研究所培育的10个花生新品系,通过自然发病和人工接种两种方法进行了白绢病抗性鉴定和产量损失研究。结果表明,在自然发病条件下,10个新品系由白绢病造成的枯萎率为11. 0%~50. 0%,其中7个品系白绢病枯萎率低于30. 0%;白绢病枯萎率与花生荚果产量呈显著负相关(r=-0. 73,P <0. 05)。在田间人工接种条件下,接种2周后,10个品系导致的植株枯萎率为66. 1%~94. 0%,收获前的白绢病枯萎率为66. 1%~97. 4%,均为感病品系;白绢病导致的植株枯萎率与花生荚果产量的相关系数为-0. 85(P <0.05)。产量损失试验表明,在人工接种条件下,所有品系产量损失均超过91. 7%,严重者几乎绝产。综合田间自然发病和人工接种鉴定,获得一份耐病品系16-A13440。

Induced Sporophore and Sclerotium of Physarum pusillum(Myxomycetes)

[Objective]The paper was to culture the plasmodia of Physarum pusillum for obtaining the optimal condition of sporophores and sclerotium,to reduce the agricultural diseases.[Method]Liquid culture combined with oat-agar culture was used to culture plasmodia of P.pusillum.Then plasmodium was induced to obtain Sporophores in lab by hunger and adjusting light（3 000,6 000,9 000,12 000 lx）and temperature（20,22,24,26 ℃）.[Result]Sporophores and sclerotium of P.pusillum were obtained from both oat-agar media and liquid media.The optimal conditions were 26 ℃,6 000 lx and 22 ℃,3 000 lx.[Conclusion]The result provided theoretical basis for reducing the loss of crops caused by myxomycete as much as possible in agricultural production.

道真玄参白绢病病原鉴定及杀菌剂毒力测定

通过对被侵染的道真玄参(Scrophularia ningpoensis Hemsl.)植株病症、病状的观察,及白绢病病菌的培养性状与菌落形态等的研究,结合ITS序列分析,最终确定该致病菌为整齐小核菌(Sclerotium rolfsii Sacc.),又名罗氏白绢小菌核菌。室内杀菌剂抑菌试验结果表明,10%多抗霉素对整齐小核菌有较好的抑制作用。

鄂西北小麦枯白穗病原物类型研究

通过对鄂西北4个不同县(市、区)冬小麦不同生育期的病样跟踪调查,初步掌握了引起鄂西北小麦枯白穗的病原物发生现状。分离培养结果表明,鄂西北小麦枯白穗是由多种病原物复合侵染所致,主要致病病原物有根腐蠕孢菌(Biopolaris)、白绢病菌(Sclerotium)、全蚀病菌(Gaemannomyces)、镰刀菌(Fusarium)、丝核菌(Rhizoctonia)和链格孢菌(Alternaria)6个属。其中全蚀病菌单胞分离方法及小麦白绢病菌菌核的培养方法均为国内首次报道。

哈茨木霉T_2菌株提取物对齐整小核菌抑菌活性的测定

采用甲醇法、乙醇法、超声波水法、碱法等4种方法对哈茨木霉菌(Trichoderma harzianum)T2菌株分生孢子中的抗菌物质进行了提取,并测定了各种粗提物对齐整小核菌(Sclerotium rolfsii)的抑菌活性及温度对粗提物抑菌活性的影响.结果表明,用不同方法提取的哈茨木霉T2菌株粗提物对齐整小核菌有不同程度的抑制效果,其中以超声波水法提取物对齐整小核菌的抑制效果较好,温度对粗提物的抑菌活性有明显的影响.

Identification of Pathogen of Gastrodia elata White Silk Disease

[ Objective] The aim was to identify the pathogen of Gastrodia elata white silk disease and explore prevention and treatment of the disease.[ Method] Infected G. elata, collected from low-mountain regions in Yichang city of Hubei Province, were isolated and purified. Then, Koch＇s Postulate was adopted to inoculate the pathogen. Finally, the identification was carried out according to its biological characteristics. [ Result] The pathogen of white silk disease belongs to weak hyperparasite. Because of its poor direct invasion ability, the pathogen usually invades into host through wound infection. According to its hyphae morphology and pathogenicity, the pathogen of G. elata White Silk Disease has been identified as Sc/erotium ro/fsii Sacc., which belongs to deuteromycotina, hyphomycetes, agonomycetales, fungi of sclerotium genus. [ Conclusion ] The study will provide references for the control of G. elata White Silk Disease caused by S. rolfsii.

基于ISSR与ITS-RFLP的花生白绢病菌遗传多样性分析

本研究利用简单重复序列区间(Inter Simple Sequence Repeat,ISSR)和ITS-RFLP技术,对采自我国12个省市的39个花生白绢病菌菌株进行遗传多样性分析。结果表明:从筛选出的17条ISSR引物共扩增出269条DNA谱带,其中多态性谱带266条,平均多态性百分率为98.9%,UPGMA聚类分析将这些菌株分为4个类群。限制性内切酶AluⅠ、RsaⅠ、HpaⅡ和MboⅠ作用内部转录间隔区(Internal Transcribed Spacer,ITS)PCR扩增产物产生的谱带,利用ITS-RFLP分析遗传多样性,将39个菌株划分为7个组群。ISSR和ITS-RFLP的结果均表明花生白绢病菌存在较高的遗传变异,但其遗传相似性与地理来源无明显相关。

PREPARATION AND STRUCTURE OF FIVE DERIVATIVES OF β-(1→3)-D-GLUCAN ISOLATED FROM PORIA COCOS SCLEROTIUM

A new solvent of cellulose (1.5 mol/L NaOH/0.5 mol/L urea aqueous solution) was used as one of the homogeneous reaction media of polysaccharides for methylation, hydroxyethylation and hydroxypropylation. A water insoluble β -(1—>3)-D-glucan, sample PCS3- isolated from fresh sclerotium of Poria cocos was sulfated in dimethyl sulfoxide (Me 2 SO), carboxymethylated in NaOH, isopropanol solution, as well as methylated, hydroxyethylated and hydroxypropylated in the new solvent system, respectively, to obtain five water-soluble derivatives coded as S-PCS3- C- PCS3- M-PCS3- HE-PCS3- and HP-PCS3- Their chemical structure and distribution of substitution were characterized by infrared spectroscopy (IR), elementary analysis (EA), 1 H-NMR, 13 C-NMR, 2D-COSY, 2D-TOCSY and 2D- 1 H-detected 1H 13C HMQC spectra. The results reveal that the relative reactivity of hydroxyl groups of the β -(1-?3)-D-glucan is in the order C-6 > C-4 > C-2 on the whole. The substitution of the samples S-PCS3- C-PCS3- and M-PCS3- occurred mainly at C-6 position and secondly at C-4 and C-2 positions, and that of HE-PCS3- occurred at C-6 and C-4 positions and of HP-PCS3- almost completely occurred at C-6 position. The degrees of substitution (DS) obtained from 13 C-NMR range from 0.23 to 1.27. The water solubility of the derivatives is in the order S-PCS3- >C-PCS3- >M-PCS3- >HE-PCS3- >HP-PCS3- This work provides a novel and nonpolluting process for the methylation, hydroxyethylation and hydroxypropylation of β -(1—>3)-D-glucan.

Streptomyces sp. RP1A-12 mediated control of peanut stem rot caused by Sclerotium rolfsii

Sclerotium rolfsii Sacc. is a destructive soilborne fungal pathogen with a wide host range that includes peanuts. Biological control offers an interesting alternative to fungicides for sustainable management of soilborne diseases. The current investigation is aimed at evaluating one potential biocontrol agent Streptomyces sp. RP1 A-12 for growth promotion and the management of peanut stem rot disease caused by S. rolfsii under field conditions. Preliminary studies conducted under in vitro and the greenhouse conditions showed promising results against the stem rot pathogen. Further in vitro and pot experiments conducted to assess Streptomyces sp. RP1 A-12 for its growth promoting abilities using whole organisms have shown an increase in seed germination, root and shoot length. Other parameters like nodule number and plant biomass were also significantly increased over control treatments indicating that the test bioagent possesses growth promoting abilities along with disease suppression capabilities. Subsequently field studies were carried out for two consecutive rainy seasons. The bioagent was applied as whole organism and partially purified crude metabolites. Results indicate the bioagent reduced stem rot disease incidence by 64–67% and 22–49% respectively in two field trials conducted with notable increase in yield. Partially purified Streptomyces sp. RP1 A-12 metabolites exhibited an even greater effect in reducing the incidence and severity of stem rot compared to the pathogen inoculated control.

INFLUENCE OF MOLECULAR WEIGHT AND PERIODATE-MODIFICATION OF β-D-GLUCANS FROM PORIA COCOS SCLEROTIUM ON ANTITUMOR ACTIVITIES

In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu.

Effect of Seed Bacterization on Plant Growth Response and Induction of Disease Resistance in Chilli

This study aimed to examine the induction of disease resistance, and growth response in chilli plants elicited by plant growth promoting endophytic bacteria [Pseudomonas aeruginosa （UPMP3）, Burkholderia cepacia （UPMB3）, and Serratia marcescens （UPMS3）]. Seed bacterization with UPMP3 and UPMB3 significantly increased peroxidase （PO）, polyphenol oxidase （PPO）, and phenylalanine ammonia-lyase （PAL） activities. This increase corresponded to greater reduction in pre-and post-emergence damping-off caused by Sclerotium rolfsii. UPMS3 alone or as mixture with UPMP3 and UPMB3 did not show any significant reduction in disease incidence. However, all the isolates tested did not inhibit the seed germination and seedling establishment in chilli.

Advances in Research on Rape Sclerotia and Resistance Breeding

Rapeseed is an important oil crop with high economic value.It can be used not only as edible oil and livestock feed,but also in medicine,industry and tourism.Sclerotium sclerotiorum is a necrotrophic fungal pathogen that harms the yield and quality of rape.This article mainly summarizes the research status of S.sclerotiorum from three aspects:the biological characteristics,infection mode,process and disease resistance breeding of S.sclerotiorum,and summarizes the future research directions of antibacterial sclerotium on rape,to provide reference for future research on sclerotinia.

In Vitro Hyphal Growth Inhibition of Plant Pathogenic Fungi by Corrigiola Telephiifolia Extracts

The sugar beet root rot and Bayoud disease, respectively caused by Sclerotium rolfsii and Fusarium oxysporum albedinis, are major agricultural problems in Morocco, affecting its economical and social conditions. As of now, no effective control method of these phytopathogens is available. Therefore the search for new efficient and ecologically undamaging fungicides was essential. The present study reports the antifungal activity of five organic extracts of Corrigiola telephiifolia Pourr., a Moroccan medicinal plant, against these fungi using mycelial growth inhibition assays （in vitro）. The extracts concentration varied from 0.01 to 1 mg.mlt. Also, preliminary information on the chemical composition of the extracts is included. The results showed a difference in sensitivity of both fungi toward the plant extracts. The mycelia growth of Sclerotium rolfsii was concentration and time-dependant. It was markedly inhibited by the polar extracts especially at high dose （p〈 0.001）. While Fusarium oxysporum f. sp. albedinis was much less sensitive.

Antimicrobial Activities of Some Plants from Ivorian Flora on Southern Blight in Cote d＇ivoire

This study aims at determining and comparing the in vitro antifungal activity of six EOs （essential oils） extracted from Monodora myristica, Melaleuca quinquenervia, Eucalyptus torelliana, Chenopodium ambrosioides, fresh Zingiber officinalis and dehydrated Zingiber officinalis with those of three synthetic fungicides （Callicuivre, Banko plus and Mancozeb） on Sclerotium rolfsii a pathogenic fungus of tomato in Cote d＇Ivoire. The products were added to PDA （potato dextrose agar） medium at various concentrations. The results showed different aspects of the mycelium, different activities on mycelium growth and sclerotia production depending on the explants （mycelium or sclerotia）. Depending on their IC and MGI （mycelium growth inhibition）, the oils stemming from Chenopodium ambrosioides and fresh Zingiber officinalis showed more inhibitory activities on mycelial growth （reduction rate of 100%） and sclerotia production at 250 ppm. These activities were close to or even greater than those of fungicides. The mancozeb fungicide showed stronger activity than the others by inhibiting mycelium growth and sclerotia production of mycelium explants at 250 ppm. This study offers the possibility of using EOs in the control strategies of Sclerotium rolfsii.

Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistance to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato

Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This study was conducted for“Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistant to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato”.The experiment was conducted at the Royal University of Agriculture and divided into two sections.The first section conducted under in vitro condition consists of four treatments T1 control treatment,T2 copper hydroxide,T3 azoxystrobin+difenoconazole,T4 metalaxyl+mancozeb in Nagoya Laboratory,and had been starting from 11st May to 15th May 2020.Section two was conducted in a pot in net-house which started from 1st January 2019 to 19th February 2019 and 1st January to 19th February 2020 and arranged in RCBD(Randomized Completely Block Design)with six replications and nine treatments.T0 negative control,T1 inoculate but not treatment,T2 metalaxyl+mancozeb,T3 azoxystrobin+difenoconazole,T4 copper hydroxide,T5 acibenzolar-S-methyl,T6 chicken dung+Trichoderma harzianum,T7 acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,T8 acibenzolar-S-methyl+metalaxyl+mancozeb.Data were collected on colonizing diameter in vitro.For pot experiment collected on disease incidence,incubation period Based on the result under in vitro condition metalaxyl+mancozeb highly inhibited germination of Sclerotium rolfsii when compared with another treatment.However,the application of copper hydroxide seems less effective compared with control.For in pot experiment,when treated after symptom of southern blight appeared to seem less effective on the severity of southern blight.In contrast,when applied as a protectant and curative when symptoms appeared only systemic fungicide azoxystrobin+difenoconazole significantly reduced the severity of Sclerotium rolfsii and delayed incubation period while compared with other treatments(p<0.05)and was followed by metalaxyl+mancozeb,whereas,copper hydroxide,acibenzolar-S-methyl,chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+metalaxyl+mancozeb were less effective(p>0.05).Based on the three experiments we can assume that fungicide is more effective in reducing the growth of the pathogen and delaying the incubation period of fungal colonization when compared with biological control and induced resistance.

Separation of scleroglucan and cell biomass from Sclerotium glucanicum grown in an inexpensive, by-product based medium

Scleroglucan is an extracellular polysaccharide produced by the fungi Sclerotium.Scleroglucan is stable over a broad range of temperatures,pH and salt concentration,thus having great potential in many diverse applications.Common media for scleroglucan production contain expensive components,such as yeast extract,that make the medium cost-ineffective for some industrial applications.Thus we developed a medium which uses Condensed Corn Solubles(CCS),a nutrient-rich byproduct of corn-based ethanol production,to replace expensive components.Methods typically used to recover scleroglucan are also expensive,and can limit commercialization.To evaluate alternative processes for scleroglucan recovery,we prepared scleroglucan in a modified version of Wang’s medium and a CCS-glucose medium.Broth samples were initially subjected to the standard recovery method to develop a complete mass balance,and then we evaluated various treatments to improve scleroglucan recovery.These included heat treatments to lyse cells,using different alcohol precipitants,freezing or refrigerating before recovery,and diluting broth to enhance cell separation.The CCS medium produced 14.2 g/L scleroglucan,compared to 10.1 g/L in the modified Wang’s medium.Based on the standard recovery protocol,we determined that 96%of the scleroglucan was recovered from the initial centrifugation and precipitation.Washing the cell pellet with water and recentrifuging only recovered a minimal amount of scleroglucan,and thus it could be eliminated from protocol to save energy and costs.Lysing cells by boiling or autoclaving did not release more scleroglucan than un-heated samples,and we also found no statistical difference between ethanol,isopopanol,and methanol as scleroglucan precipitants.Refrigerating the broth prior to scleroglucan recovery had no significant effect,while freezing actually decreased scleroglucan recovery.Initially diluting the broth by 0.50 or 0.34 resulted in the greatest scleroglucan recovery,while higher or lower dilutions decreased recovery.The optimum protocol for scleroglucan recovery was a 0.50 dilution of broth prior to centrifugation,no washing of the cell pellet,and use of the least expensive alcohol to precipitate scleroglucan from the supernatant.