Induced Resistance by the Toxin Filtrate of Bipolaris maydis Race T Cultivation

Resistance to maize southern leaf spot disease was induced by the low-concentration filtrate of Bipolaris maydis race T cultivation in an experiment. The nuclear neterogeny corn C103 was used as the test material. The lesion area on the leaves was significant difference by connalysis. The lesion areas on pretreated leaves were (0.3 ± 0.05)- (0.9 ± 0.5) mm2, but those on the control were (23.1 ± 8.7) mm2. At the same time, the changes in peroxidase, phenylalanine, ammonialyase, and malondialdehvde activities were determined. During 0-96 h of inspection, phenylalanine and ammonialyase (PAL) activities increased by 64.2%, peroxidase (POD) activities increased by 41.2%, but the malondialdenvde (MDA) content decreased by 29.7% compared with the control. It seems that the low-concentration filtrate of Bipolaris maydis race T cultivation itself can be used as an elicitor to enhance the induced resistance.     

玉米小斑病重要流行环节的初步定量研究Ⅱ病斑产孢、孢子飞散、杀菌剂筛选

采用室内和田间观察试验,对玉米小班病的重要流行环节——病斑产孢、孢子飞散、杀菌剂筛选进行了研究。结果表明:在饱和湿度下病斑上孢子梗产生较快;保湿10 h病斑很少产孢,25 h后大量产孢,到35 h后产孢基本不再增加;在直射光下病斑不产孢,在散射光下产孢量大于在黑暗条件下产孢量;病斑产孢的适宜温度为20~30℃,最适温度26℃,5℃以下、35℃以上不能产孢。随玉米生育期的推进,单株病斑产孢量有所减少。孢子飞散白天多于夜间。阿米西达、代森锰锌(新万生、大生)、炭疽福美、福美双、百菌清等杀菌剂对玉米小斑病菌毒力较强,而多菌灵、甲基托布津、三唑醇、甲霜灵等药剂基本无效。     

海域霉菌对植物病原真菌抗性的研究

以玉蜀黍平脐蠕孢菌(Bipolaris maydis)和大豆尖孢镰刀菌(Fusarium oxysporum)为指示菌株,采用平板对峙培养法初步测定渤海海洋霉菌的抑菌活性,再用牛津杯扩散法对初筛获得的活性菌株的发酵液进行抑菌活性测定。结果表明,菌株67对玉蜀黍平脐蠕孢菌和大豆尖孢镰刀菌有很强的抑制作用,菌株32对玉蜀黍平脐蠕孢菌有较好的抑制作用。将菌株67在28℃,180 r/min条件下发酵培养66 h,生物量达到7.054 mg/mL,在54~120 h的发酵时间内,发酵液均具有抑菌活性,发酵96 h时抑菌效果最明显,对F.oxysporum和B.maydis的抑菌圈直径分别为20.3 mm和13.6 mm。同时发现,菌株67发酵液的抑菌活性不仅与发酵时间有关,而且与发酵液的pH值相关,具有明显的抑菌活性的发酵液的pH范围为4.0~5.0。     

玉米小斑病生理小种的侵染特征与玉米雄性不育胞质的利用

详细叙述了玉米小斑病Ｔ、Ｃ小种的侵染特征，并在对二者分析比较的基础上，提出了玉米雄性不育胞质的利用途径：（１）育成异型胞质杂交种；（２）在同一地区内推广分别属于不同胞质类型的同一杂交种或不同杂交组合；（３）不育胞质与正常胞质杂交种掺合使用；（４）无论哪种方法，都应以选育抗小斑病Ｏ小种或其它小种的核背景为前提     

苦瓜平脐蠕孢叶斑病病原鉴定

This study was conducted to identify the pathogens causing a new leaf spot disease on bitter gourd. The diseased leaves were collected from bitter gourd plantations around Nanning, Guangxi province. The pathogen causing this disease was identified by pathogenicity, morphology, and combined gene sequences analysis on ITS, TEF and GPD. The morphological characteristics of the pathogen were similar to that of Bipolaris bicolor. The representative isolate was clustered into one clade in phylogenetic tree with B. bicolor, which indicated that the leaf spot of bitter gourd was caused by B. bicolor. This is the first report of a leaf spot disease caused by B. bicolor on bitter gourd.     

Population genetic structure,gene flow and recombination of Cochliobolus miyabeanus on cultivated wildrice (Zizania palustris)

A collection of 168 Cochliobolus miyabeanus isolates was made from cultivated wildrice (Zizania palustris) paddies in Minnesota, USA, during 2007 and 2008. Analysis of 26 polymorphic amplified fragment length polymorphism (AFLP) markers generated with three primer‐pair combinations indicated a moderate average gene diversity () of 0·283. Genotypic diversity was high in all collection areas with the exception of a paddy in Itasca County. Significant population subdivision by collection site was found with amova tests using both the entire fungal population data (F_ST = 0·29, P < 0·001) and the clone‐corrected data (F_ST = 0·08, P < 0·001), and with a Markov chain Monte Carlo approach. Abundant immigrants, shared haplotypes and admixed genotypes were found in paddies in central‐eastern areas. Although indirect tests did not support the hypothesis of random mating at the subpopulation level, sexual recombination nevertheless may be possible in areas where both mating type idiomorphs, MAT1‐1 and MAT1‐2, were found. These results may have implications in breeding for resistance and disease management.     

具有除草活性的小麦根腐病菌发酵条件优化

通过单因子试验和正交试验对小麦根腐病菌菌株进行了发酵条件优化,以提高其活性物质的产量。结果表明:最适合小麦根腐病菌产毒的培养基是察氏培养基;该培养基的最佳碳源为葡萄糖,氮源为氯化铵,无机盐为氯化钾、磷酸氢二钾、硫酸镁和硫酸亚铁;发酵培养基各组分的最佳配比为:葡萄糖2.0%,氯化铵0.25%,氯化钾0.05%,磷酸氢二钾0.025%,硫酸镁0.025%,硫酸亚铁0.000 5%;有利于提高菌株活性物质产量的培养条件为初始pH7.0,转速为130r/min,温度为28℃,培养时间为5d,装液量为120mL/250mL,接种量为6%。小麦根腐病菌菌株发酵产物具有良好的热稳定性和光稳定性,在弱酸性及中性条件下较稳定。发酵条件优化后提高了小麦根腐病菌的除草活性。     

杉木幼苗梢枯病的研究

杉木幼苗梢枯病是杉木产区发生的一种危害苗木的新病害,为了摸清引起病害发生的病原菌和抑制病原菌的有效药剂,通过多次对病苗进行组织分离、培养、纯化,获得平脐蠕孢属(Bipolaris)真菌的纯培养;通过杉木苗期的室内有伤、无伤接种和再分离试验,证明该病菌对杉木苗有很强的致病力,并能引起与自然发病一致的症状,是杉木幼苗梢枯的主要病原菌;通过百菌清、白色甲托、多菌灵、萎立、代森猛锌、三环唑6种杀菌剂的毒力测定结果表明,70%白色甲托可湿性粉剂、75%百菌清可湿性粉剂、40%萎立可湿性粉剂对该病菌的菌丝和孢子生长都有较强的抑制力,这3种药剂可用于田间试验,进一步研究其对杉木幼苗梢枯病的防治效果,并在生产上推广应用。     

火龙果黑斑病菌[Bipolaris cactivora（Petrak）Alcorn]生物学特性研究

为了明确分离自火龙果黑斑病的病原种类、生物学特性及防治方法,对该病菌进行了种类鉴定、生物学特性研究以及室内药剂筛选。结果表明,引起该火龙果病害的病原菌为仙人掌平脐蠕孢[Bipolaris cactivora（Petrak）Alcorn]。该病菌菌丝生长最适温度是30 ℃,产孢最适温度20 ℃。菌丝生长最适pH为5,产孢最适pH8。光照对菌丝生长无显著影响,黑暗条件有利于产孢。菌丝生长最佳碳源是葡萄糖和D-果糖,产孢最佳碳源为甘露醇。菌丝生长和产孢的最佳氮源均为蛋白胨,菌丝致死温度为70 ℃,10 min。