水稻恶苗病菌对三种浸种剂的抗性及抗药菌株的竞争力

从江苏13个地区采集病样,并分离获得水稻恶苗病菌Fusarium moniliforme548个菌株,检测其对多菌灵、咪鲜胺和浸种灵等三种浸种剂的抗性及抗药菌株的竞争力。结果发现,以10μg/mL(MIC)为检测标准,抗多菌灵菌株频率平均为95.8%,其中高抗菌株(MIC>100μg/mL)占82.7%,少数高抗菌株EC50>1000μg/mL,且抗性稳定;菌株敏感性频率分布法测定水稻恶苗病菌对咪鲜胺的敏感基线为(0.00075±0.00003)μg/mL(EC50)和0.85μg/mL(MIC),以3μg/mL(MIC)为检测标准,抗咪鲜胺菌株有8个,抗性菌株频率平均为1.5%,且均为高抗(抗性倍数103.1~126.2)或中抗(抗性倍数24.6~95.0)水平,但经转管培养5~20代后菌株抗性显著下降;以同样方法测定水稻恶苗病菌对浸种灵的敏感基线为(1.265±0.014)μg/mL(EC50)和3.13μg/mL(MIC),以5μg/mL(MIC)为标准,未检测到抗浸种灵菌株。此外,抗、感菌株分生孢子等量混合液接种结果表明,抗多菌灵菌株在水稻上竞争力较强,而抗咪鲜胺菌株竞争力较弱。     

利用伏马毒素合成基因对玉米种子寄藏镰刀菌的分子检测

我国玉米种子普遍受到拟轮生镰刀菌(Fusarium verticillioides)的侵染,该菌产生的伏马毒素对国家种质库中玉米种质的安全保存有着潜在的影响。fum1基因是F.verticillioides等镰刀菌中伏马毒素生物合成的必需基因。选用3对已知引物Fum5F/Fum5R、P1/P2和P3/P4分别对从玉米种子中分离出的9株镰刀菌和1株阴性对照菌链格孢菌进行PCR扩增检测,在F001和F003菌株中扩增出相应的特异性表达片段。测序表明,这些片段的长度分别为846bp、888bp和703bp,与已知fum1基因(AF155773)的同源性达99%以上。3对引物的检测灵敏度达到88pg/mL。结果表明,这3对引物都能够有效地检测产生伏马毒素的镰刀菌菌株,但引物Fum5F/Fum5R所扩增片段完全来自fum1基因内部,具有更强的特异性。在此定性检测基础上,需要进一步研究定量检测方法并进一步研究伏马毒素对农作物种质保存的影响。     

放线菌YIM34165发酵提取物抗水稻恶苗病菌的活性研究

从云南土壤中分离的放线菌YIM34165,优选3种不同培养基(1号、61号和301号)进行发酵,测定其发酵提取物对水稻恶苗病菌的活性,结果表明:61号培养基的发酵提取物对水稻恶苗病菌丝生长的抑制效果明显,病菌孢子萌发抑制率为84.27%,活体平均防治效果为82.45%。     

籽用西瓜种质资源抗枯萎病离体筛选技术的研究

以籽用西瓜中信1号红籽瓜不定芽为筛选材料,利用镰刀菌酸(Fusariumacid,FA)为胁迫剂,进行红籽瓜抗枯萎病无性系变异体离体筛选技术和红籽瓜种质资源抗病性鉴定的研究。结果表明,红籽瓜体细胞无性系抗性变异体离体筛选的FA适宜浓度为15mg.L-1。初步建立了红籽瓜抗性变异体离体筛选体系,获得了抗FA变异体的再生植株。筛选出红籽瓜种质资源高抗材料2份,中抗材料6份,轻抗材料11份,高感材料17份。     

厚皮甜瓜嫁接防治枯萎病试验研究

利用嫁接防治枯萎病在西瓜生产中已普及,但在甜瓜上应用较少。本试验以10种砧木为试材,拟为甜瓜嫁接栽培筛选适宜的砧木。嫁接防病试验结果表明,采用地方瓜种1笋瓜和日本新土佐南瓜等10种砧木嫁接海蜜3号甜瓜,可显著提高甜瓜的抗枯萎病能力,除菜瓜和永康组合有少许发病株外,地方瓜种1和新土佐组合防病效果均达100%,而对照海蜜3号自根嫁接植株的病株率为8.5%;亲和性,新土佐组合好于自根嫁接的对照,地方瓜种1组合总体上逊于对照;667m2产量新土佐超过对照116kg,地方瓜种1超过对照142kg;地方瓜种1组合与对照果肉质地、颜色相近,可溶性固形物含量高于对照,新土佐组合果实质地软,口感较淡,可溶性固形物含量略低于对照。地方瓜种1和日本新土佐可作为海蜜3号甜瓜的砧木在生产上应用。     

Polygalacturonase-inhibiting protein activity in cantaloupe fruit as a function of fruit maturation and tissue origin

Netted cantaloupe (Cucumis melo var. cantalupensis cv. Magnum 45) were harvested from 5 to 35 days postanthesis. The fruit of each age group were divided into exocarp, outer mesocarp, mid mesocarp, inner mesocarp, placenta, and seed. Each tissue was extracted and assayed for polygalacturonase-inhibiting protein (PGIP) activity against polygalacturonases (PGs) from three fungal pathogens of cantaloupe fruit. The PGIP activity of all tissues except placenta was high from the flower stage through the first week of fruit development but decreased markedly between 5 and 10 days postanthesis. PGIP activity against Phomopsis cucurbitae PG remained high and nearly constant in placental tissue throughout fruit development. However in this same tissue, PGIP activity against Fusarium solani PG decreased during fruit development to about 25% of its level in the 5-day-old fruit. This differential change in PGIP activity toward the two PGs suggests that different forms of the inhibitor are expressed between early and late stages of cantaloupe fruit development. The results also illustrate the importance of using multiple pathogen enzyme systems that can provide an opportunity for more accurate elucidation of mechanisms involved in the host–pathogen interaction. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. All programs and services of the US Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, or handicap. The article cited was prepared by a USDA employee as part of his/her official duties. Copyright protection under US copyright law is not available for such works. Accordingly, there is no copyright to transfer. The fact that the private publication in which the article appears is itself copyrighted does not affect the material of the US Government, which can be freely reproduced by the public.     

Increasing control reliability of <Emphasis Type="Italic">Orobanche cumana </Emphasis>through integration of a biocontrol agent with a resistance-inducing chemical

Fusarium oxysporum Schlecht. f.sp. orthoceras (Appel & Wollenw.) Bilai is a potential biocontrol agent against the root-parasitic weed Orobanche cumana. In pot experiments with different sunflower cultivars, the application of F. oxysporum was combined with a treatment of BTH (Benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester), a product known to induce resistance against O. cumana in sunflower. The combined treatments resulted in highly reliable control and sometimes in increased control level compared to the Fusarium treatment alone. In laboratory experiments, no enhancing effect of BTH on virulence and growth of the fungus was observed. Future experiments should further investigate the basic mechanisms of the effect achieved by combining the two control strategies as well as the transfer of this innovative control approach into field experiments.     

人工接种法鉴定评价西瓜枯萎病抗性新品种

西瓜枯萎病是西瓜产业中最为重要的土传病害之一，利用抗病品种仍然是最理想的防治途径，然而新培育的抗病品种引入其他地区后抗性容易丧失，因此了解新品种抗性特点有助于品种推广应用。本试验通过菌土接种法鉴定了8 个西瓜品种对枯萎病生理小种1 的抗性，并利用分子标记进行验证。结果显示，6 个供试西瓜新品种表现为中抗，与分子标记检测结果一致。其中申选958、申蜜968 和申蜜6 号在3 次不同时间的重复试验中抗性表现差异较大，表明其抗性对环境因子尤其是温度和湿度较敏感。申抗988 与申选958 具有相同的抗病亲本，且分子标记检测基因型一致，但在相同环境条件下二者抗性表现差异也较大，表明由于亲本材料不同，品种间可能存在不同的微效基因或基因互作方式。     

小麦赤霉病菌拮抗菌筛选及最适培养条件初步研究

Fusarium head blight is one of the most important diseases in the world and is a major disease on wheat in China. Therefore, this study aimed to isolate antagonistic bacteria with strong inhibitory effects on F. graminearum, and to provide theoretical basis for biological control of FHB. Endophytic strains were screened by plate confrontation and were identified by 16S rDNA sequence analysis. Among seven isolated antagonistic strains, WJ-2 was the best one with 15.4 mm bacteriostatic circle in diameter. Through analysis on 16S rDNA sequence and physiological and biochemical characteristics, strain WJ-2 was preliminarily identified as Bacillus subtilis.     

禾谷镰孢漆酶样多铜氧化酶的鉴定及其表达模式

 子囊菌禾谷镰孢(Fusarium graminearum)可侵染玉米茎部造成严重的玉米茎腐病。漆酶样多铜氧化酶(Laccase-like multicopper oxidase)具有广泛的作用底物且在植物病原真菌中参与病菌侵染,促进病菌定殖。利用已知真菌漆酶的蛋白序列在禾谷镰孢中鉴定得到14个漆酶样多铜氧化酶,分属5种亚家族。通过对其在侵染玉米茎部不同时间后的芯片数据分析表明FGSG_02142、FGSG_05159在菌丝、孢子及侵染各阶段表达量均较高,FGSG_02328、FGSG_13185和FGSG_00142在侵染阶段表达量明显增加,其他基因表达量相对较低;试验进而利用qPCR检测了部分差异基因在接种玉米感病种质资源B73和抗病种质资源Mo17中的相对表达量,结果显示,禾谷镰孢FGSG_00142基因在B73中的表达量明显高于在抗病材料Mo17中的表达量,而毒素相关基因FGSG_02328在接种Mo17时表达也出现延迟,推测这2个基因均参与了禾谷镰孢的侵染过程。