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1.
Jones JB Bouzar H Somodi GC Stall RE Pernezny K El-Morsy G Scott JW 《Phytopathology》1998,88(1):33-38
ABSTRACT Until recently, tomato race 1 (T1) of Xanthomonas campestris pv. vesicatoria was the only race causing bacterial spot of tomato in Florida. In 1991, tomato race 3 (T3) was first identified in 3 of 13 tomato production fields surveyed. By 1994, T3 was observed in 21 of 28 fields and was the only race identified in 14 fields. In field studies, tomato genotypes with resistance to either T1 or T3 or susceptibility to both were co-inoculated with strains of both races. Lesions on 10 plants in each of three replications for each genotype were sampled three times during the experiment; bacterial isolations were made from each lesion, and tomato race identifications were made for each strain. At the third sampling date, T3 was isolated from 97% of the lesions on the susceptible genotype Walter and the T1-resistant genotype Hawaii 7998, while T3 was isolated from 23% of the lesions and T1 from the remaining 77% on the T3-resistant genotypes PI 128216 and PI 126932. In surface population studies done in growth rooms, suspensions of T1 and T3 were applied alone and in combination to the leaf surfaces of susceptible and resistant genotypes. T1 populations were reduced more than 10-fold when applied in combination with T3, compared with populations that developed when T1 was applied alone. T3 populations were not affected when applied in combination with a T1 strain. In greenhouse studies with the T3-resistant genotype Hawaii 7981, disease was significantly reduced in plants inoculated with T3 in combination with T1, compared with plants inoculated with T1 alone. These results clearly demonstrate the competitive nature of T3 in the presence of T1 and help explain the emergence of T3 as a prevalent race in Florida. 相似文献
2.
A total of 404 isolates of Xanthomonas campestris pv. vesicatoria , obtained from Capsicum chinense cv. West Indian Red grown in Barbados and Grenada, were differentiated into pathogenic races, and of these, 96 were tested also for selected taxonomic group phenotypes. The response of C. chinense to infection by several X. campestris pv. vesicatoria races and the contribution of races isolated from this cultivar to severity of bacterial spot of bell pepper and tomato were also investigated. P4T2, P5T2 and P6T2 were the predominant races of X. campestris pv. vesicatoria isolated from C. chinense grown in Grenada, whereas nine races (T1, P4, P6, P0T2, P1T2, P4T1, P4T2, P6T1 and P6T2) were isolated in Barbados. Race P4T2 comprised 46.0 and 71.4% of the isolates from Barbados and Grenada, respectively. The 96 isolates, all of which overcame resistance conferred by the gene Bs2 , shared taxonomic group B strain characteristics, including the presence of the β-protein band, positive amylolytic activity and inability to oxidize cis -aconitate. The C. chinense cv. West Indian Red was susceptible only to races of X. campestris pv. vesicatoria that can overcome Bs2 gene resistance. Of six such races identified in Barbados, only P4T1, P4T2 and P6T1 affected bacterial spot-susceptible bell pepper or tomato in the field, and they amounted to only 1.5–2.1% of each sample of isolates from these plant species. Moreover, they were confined to the smallest bacterial spot lesions. Bell pepper was most severely affected by combinations of races T1 with P3T2 and T2 with P0T1, and tomato by race T1 only and combinations of races P0T1 with P0T2 and P1T1 with P1T0, all of which prevailed in the field despite selection against them by C. chinense cv. West Indian Red. 相似文献
3.
为明确木霉菌在玉米纹枯病防治上的作用,研究了从雅安郊区大田玉米根际土壤中分离到的18个木霉菌株对立枯丝核菌的抑制作用及对玉米纹枯病的田间防治效果.对峙培养结果表明,这些木霉菌株对立枯丝核菌的抑制率为39.44%～84.98%;而木霉发酵滤液的抑菌作用为13.48%～85.81%.对峙培养和液体发酵滤液的抑菌测定相结合,筛选出木霉菌株T8、T2、T13,经鉴定分别为哈茨木霉Trichoderma harzianum、黄绿木霉Trichoderma aureoviride和长枝木霉Trichoderma Longibrachiatum.用这3种木霉的固体培养物作进一步的田间防治试验,防治效果分别为62.75%、64.48%、68.52%,比井冈霉素(49.68%)效果高;T13菌株的发酵滤液的防治效果仅为40.07%.3株木霉固体培养物对玉米产量影响显著,增产率依次为29.77%、43.37%、54.21%. 相似文献
4.
浙江省马尾松毛虫的赤眼蜂种类调查及用柞蚕卵繁蜂对优势种的影响 总被引：1，自引：0，他引：1
1988～1989年在浙江省11个县(市)作马尾松毛虫卵期赤眼蜂抽样调查,经雄蜂外生殖器鉴别,明确有松毛虫赤眼蜂和拟澳洲赤眼蜂2种,1988年全年林间调查,二者分别占样本总数的86.85％和13.15％,松毛虫赤眼蜂处于优势,拟澳洲赤眼蜂只在一定时期和局部地区占优势。同年对繁蜂站所用的种蜂作考查,拟澳洲赤眼蜂和松毛虫赤眼蜂分别占样本数的85.71％和14.29％,即拟澳洲赤眼蜂占优势,但经在柞蚕卵上转主接蜂传代后,松毛虫赤眼蜂的优势得以提高和稳定,在子蜂中占96.15％。在放蜂区林间复查,松毛虫赤眼蜂仍保持优势,占样本数的99.42％。 相似文献
5.
ABSTRACT Eyespot of wheat is caused by the discomycete fungi Tapesia yallundae and T. acuformis. T. yallundae is considered the most important causal agent of the disease in this region but no apothecia of either species have been found in the U.S. Pacific Northwest (PNW). Two compatible isolates of T. yallundae from the PNW were used to inoculate a field plot in the fall of 1998 and apothecia developed in the spring and fall of 2000 on standing wheat stubble. In the spring of 2000, wheat stubble from eight naturally infected fields was examined for the presence of apothecia of T. yallundae and T. acuformis. Apothecia of T. acuformis were found in two fields but no apothecia of T. yallundae were found. This is the first report of apothecia of the eyespot pathogens occurring in the PNW. Species and mating-type distribution of T. yallundae and T. acuformis in the PNW were determined from 817 isolates collected from diseased wheat over 3 years at spatial scales ranging from within fields to across states. In all, 460 isolates were identified as T. yallundae and 357 isolates were identified as T. acuformis with MAT1-1/MAT1-2 ratios not significantly different from 1:1 based on chi(2) tests at most scales tested. The apparent increase in frequency of T. acuformis from previous surveys may indicate a shift in the predominant species causing eyespot. The occurrence of apothecia under field conditions, along with the widespread distribution of mating types of both species, suggests that sexual reproduction may be occurring in both species. 相似文献
6.
云南石榴蓟马种类组成及其种群动态 总被引：3，自引：0，他引：3
2007-2008年对云南甜石榴和酸石榴两种石榴上蓟马种类及其种群动态进行了系统调查、标本采集、种类鉴定。结果表明,为害石榴的蓟马有10种,分别为西花蓟马(Frankliniella occidentalis)、丽花蓟马(F.intonsa)、黄蓟马(Thripsflavus)、黄胸蓟马(T.hawaiiensis)、棕榈蓟马(T.palmi)、烟蓟马(T.tabaci)、茶黄硬蓟马(Scirto-thrips dorsalis)、端大蓟马(Megalurothrips distalis)、华简管蓟马(Haplothrips chinensis)和Thripssp.,其中西花蓟马是云南石榴蓟马的优势种。不同石榴品种上蓟马种类不同,甜石榴上有西花蓟马、丽花蓟马、黄蓟马、棕榈蓟马、烟蓟马、黄胸蓟马、端大蓟马、茶黄硬蓟马和蓟马属1种,酸石榴上蓟马种类有西花蓟马、丽花蓟马、黄蓟马、棕榈蓟马、烟蓟马、端大蓟马、茶黄硬蓟马、华简管蓟马和蓟马属1种,黄胸蓟马仅在甜石榴上发生为害。在石榴不同生育时期,发生为害不同,其中成虫和若虫集中为害花,造成麻点特征。 相似文献
7.
为探究蠋蝽低温饲养效果,延长蠋蝽货架期。本研究对低温T1（15℃）和T2（10℃）条件下,小群体饲养的初始处理龄期为3龄、4龄、5龄蠋蝽若虫及成虫的部分生长发育参数和蜕皮激素含量进行测定分析。研究结果表明：随着饲养温度降低,蠋蝽食物与水的更换（补给）频次降低,蠋蝽在T1和T2温度条件下均能发育、但若虫发育历期随温度降低显著延长,蠋蝽羽化成虫后的虫体质量随温度和初始饲养龄期的降低而降低;T2-3（“-”后的数字代表蠋蝽龄期）组蠋蝽若虫不能发育至成虫,T1-3和T2-4组蠋蝽若虫可以发育至成虫、但较多成虫翅畸形,T1-3和T2-3组5龄若虫蜕皮后第5 d的蜕皮激素含量（27.37 ng/L和24.21 ng/L）显著低于CK-3（30.16 ng/L）;T1-4、T1-5和T2-5组蠋蝽若虫能发育至成虫,且T1-4和T1-5组蠋蝽羽化的成虫可以在该温度下交配产卵（7.04粒、10.25粒）;T2组中仅有T2-5、T2-雌成虫两组蠋蝽在恢复饲养观测期内有产卵（9.24粒、17.05粒）,但产卵量显著低于CK组（27.26粒）,T1温度各组均在恢复饲养观测期内有产卵,且高龄期组卵量显著高于低龄期组。 相似文献
8.
哈茨木霉菌(Trichoderma harzianum)和终极腐霉菌(Pythium ultimum)对玉米蛋白质组的影响(I) 总被引：1，自引：0，他引：1
哈茨木霉(Trichoderma harzianum) T22菌株已普遍用于防治包括由终极腐霉(Pythium ultimum)引起的苗病或根腐病在内的各种病害。玉米自交系Mo17种子经T22处理后播种在接种腐霉或未接种的田间土壤内,5 d后取幼苗的根系或幼茎提取蛋白。结果表明:在接种腐霉菌的土壤内,未进行T22处理的5 d龄幼苗长势明显比对照差,而经T22处理的幼苗长势明显比对照好。T22和腐霉菌复合处理及T22单独处理对幼苗生长影响基本相同。本研究建立了蛋白质提取和双向电泳分离技术。通过双向电泳及相应的分析软件(PDQuestTM 2-D softw are)可将不同处理的幼苗自交系蛋白进行分离。T22菌株处理的根系产生104种上游调控蛋白和164种下游调控蛋白,T22与腐霉菌复合处理可产生97种上游调控蛋白和150种下游调控蛋白,而用腐霉菌单一处理诱导的上游或下游蛋白的数量明显少于上述2个处理。T22或腐霉菌单一或复合处理的根系蛋白质组图谱与空白对照相比差异显著,它们与对照的蛋白质组图谱相似系数分别为0.72、0.51和0.49;T22与腐霉菌分别处理的蛋白质组图谱间也相差明显,两者的相似系数仅为0.65。进一步研究发现,T22菌体蛋白质组图谱与上述各种处理的蛋白质组图谱相似系数均很低,说明各种处理诱导后的幼苗根系蛋白质组组分主要来自植物本身,其变化主要因T22或腐霉菌的诱导所致。腐霉菌的侵染对寄主根系蛋白组图谱影响明显高于T22的作用。蛋白质组中各种蛋白质的质谱分析(M ALDI-TOF)与鉴定将另文发表。 相似文献
9.
ABSTRACT Tomato race 3 (T3) strains of Xanthomonas campestris pv. vesicatoria are antagonistic in vitro to tomato race 1 (T1) strains of the bacterium. All T1 strains and 11 strains of other X. campestris pathovars tested were inhibited by T3 strains. Sensitivity of tomato race 2 (T2) strains was variable. No strains from other bacterial genera tested were inhibited. Cell-free filtrates from T3 strains were inhibitory to sensitive strains. The inhibitory activity of these filtrates was lost after treatment at temperatures above 80 degrees C and with selected protease enzymes. However, treatment with trypsin or DNase had no effect on their activity. Seven cosmid clones from a genomic library of a T3 strain were selected for their ability to consistently inhibit a sensitive indicator strain in plate assays. Southern hybridization analysis placed these into three bacteriocin (BCN)-producing groups designated BCN-A, BCN-B, and BCN-C. The BCN-like groups could be differentiated by variations in inhibitory spectra and levels of activity in plate assays. Mutations that inactivated expression of each BCN group individually in a wild-type T3 strain had inhibitory activity confirming that multiple BCNs are present in the T3 strain. T3 strains were inhibitory to a sensitive indicator strain in tomato leaf tissue, but this effect was observed only when T3 strains were applied in advance of the sensitive strain. BCN-A was the major BCN-like substance involved in the suppression of the sensitive indicator strain in tomato leaf tissues. 相似文献
10.
采用“轮作、休闲、连作、间作、休闲1年-种植”5种耕作模式,结合通径分析,研究不同耕作制度对胡麻土壤酶活性变化特征的影响,以及土壤养分对土壤酶的影响效应。结果表明：（1）胡麻枞形期,研究区表土层4种土壤酶活性各处理间无显著差异（P＜0.05）,说明不同耕作制度在胡麻生长前期对土壤酶影响不明显;盛花期,蔗糖酶活性T1、T2、T3和T4分别较T5提高44.6%、53.3%、61.9%和34.9%,脲酶活性T5、T1和T2分别较T4提高266.0%、157.0%和140.0%,碱性磷酸酶活性T3较T2提高54.0%;硕果期,过氧化氢酶活性T2 和T3分别为1.41 mL·g-1·h-1和1.51 mL·g-4·h-1,显著高于T1、T4和T5;（2）胡麻盛花期,亚土层土壤脲酶活性T2和T5分别为1.74 mg·g-1·d-1和1.70 mg·g-1·d-1,显著高于T1、T3和T4;过氧化氢酶活性T1较T5提高212.0%,碱性磷酸酶活性T5较T4提高了21.6%;（3）蔗糖酶与碱性磷酸酶间显著负相关,与脲酶间正相关,其余酶为负相关;（4）耕层不同土壤酶活性受土壤养分因子影响的多重效应不同,pH、全磷含量能够促进蔗糖酶、过氧化氢酶活性提高,有机质、pH含量促进碱性磷酸酶活性提高;亚土层不同土壤酶活性受土壤因子影响的多重效应增加,主要为限制因子,且限制因子数要远大于表土层。 相似文献
11.
深绿木霉T2菌株对百合疫霉拮抗作用及机制 总被引：2，自引：0，他引：2
本文采用对峙培养、抗生物质测定、对扣培养、圆盘滤膜法、酶活性测定等方法,研究了深绿木霉对百合疫霉病菌的拮抗作用及机制。结果表明,深绿木霉T2菌株具有较强的营养竞争与重寄生作用;并发现其有抗生物质和溶菌酶类产生,对峙培养60 h时,深绿木霉生长速率是百合疫霉的3.68倍,能够与其竞争营养,抑制了百合疫霉的生长与扩展,深绿木霉寄生在百合疫霉菌丝上生长,导致百合疫霉菌丝降解;其代谢产物能够抑制百合疫霉的生长,48 h时难挥发性和易挥发性代谢产物对百合疫霉的抑菌率分别为85.07%和79.10%;深绿木霉T2菌株的发酵液有较高的β 1,3 葡聚糖酶活性,并在第5天达到峰值,为18.54U;深绿木霉发酵液对百合疫霉菌丝有降解作用。 相似文献
12.
为探明保水剂施用条件下冬小麦生长与水肥利用的特征,采用田间试验,以不施保水剂和氮肥为对照,研究了单施氮肥(T2:225 kg·km-2)和其与不同用量保水剂配施(T3:N+保水剂30 kg·hm-2、T4:N+保水剂60 kg·hm-2、T5:N+保水剂90 kg· hm-2)处理对冬小麦生长、土壤矿质氮含量以及水肥利用等影响。结果表明:保水剂与氮肥的施用显著提高了小麦各生育期的小麦总群体、株高、叶面积、土壤矿质氮含量及水肥利用率等。各处理中,以T4处理对于总群体数、株高、穗长和穗粒数的提高效果最为显著,而T5处理对于小麦叶面积和千粒重的提高作用明显。随小麦生育期的推进,保水剂处理的根冠比均较对照低,尤其是T3处理。而各生育期土壤矿质氮平均含量表现为T4＞T3＞T5＞T2＞CK。最终小麦产量、氮肥农学效率、氮素生产力和水分利用效率,随保水用量的增加而先增后将,且均匀以T4处理最高,其分别比单施氮肥处理(T2)14.5％、55.9％、34.6％和25.0％。说明各处理中,以T4处理对小麦的生长、增产及水肥利用的效果最佳。 相似文献
13.
ABSTRACT Histochemical staining, beta-glucuronidase (GUS) activity, or placing roots on agar were methods used to characterize interactions between the pathogenic fungus, Fusarium oxysporum f. sp. lycopersici, and the nonpathogenic biocontrol F. oxysporum strain 70T01 with respect to colonization behaviors, interaction sites, and population densities on tomato roots. Mycelia of strain 70T01, a genetic transformant expressing stable GUS activity, hygromycin B resistance, and effective disease control, were localized in epidermal and cortex cell layers of tomato roots in a discontinuous and uneven pattern. In contrast, mycelia of F. oxysporum f. sp. lycopersici were found in the vascular bundles. Thus, direct interactions between the two fungi likely happen in the root surface cell layers. Colonization density of strain 70T01 was related to the inoculation density but decreased with distance from the inoculation site. Host defense reactions, including increased cell wall thickness or papilla deposits, were adjacent to 70T01 hyphae. Experiments done in soil showed that strain 70T01 densities in roots were highest at inoculation zones and barely detectable for root segments more than 2 cm away from the inoculation sites. F. oxysporum f. sp. lycopersici densities were lowest at 70T01 inoculation zones and highest (>10 times) where strain 70T01 was not directly applied. Newly elongating roots where strain 70T01 did not reach were available for infection by the pathogen. The higher strain 70T01 density was always found when the plants were simultaneously infected by F. oxysporum f. sp. lycopersici, suggesting that F. oxysporum f. sp. lycopersici has as much influence in predisposing the plant to colonization by strain 70T01 as strain 70T01 has on providing disease protection against the pathogen. 相似文献
14.
应用改进的多克隆抗体Western blot技术研究柑桔速衰病毒蛋白 总被引：1，自引：0，他引：1
本文利用多克隆抗体发展了一种无背景的Western blot技术并用于研究柑桔速衰病毒(CTV)的蛋白。结果表明,利用CTV兔多克隆抗体1212和1052发展的Western blot技术可以检测到感染CTV的墨西哥酸橙或Citrus excelsa植株内CTV的4种蛋白P1、P2、P3和P4。在健株或病株内杂交反应均无非特异性背景。从不同寄主上分离到的CTV不同分离物的蛋白条带是不同的。利用1212和1052抗体均可以检测到感染6个CTV分离物的墨西哥酸橙幼苗内的P1、P2和P3。利用1052抗体能检测到感染严重型分离物T36、T3和Mm2的墨西哥酸橙幼苗内微弱的P4,但感染轻型分离物T30、T26和T4的幼苗内则检测不到。利用1212抗体检测不到P4。在C. excelsa内,1212和1052抗体均能检测到感染所有分离物的病株内的P1。在感染T3、T26、T4或Mm2的病株内能检测到P2,但在感染T30和36分离物的病株内则检测不到。在感染T36、T3、T26、T4和Mm2的病株内可检测到P3,但在感染T30的病株内则检测不到。在大多数植物内,P1、P2、P3和P4的分子量分别约为25kDa,24kDa,21kDa和18kDa。在感染T36分离物的C. excelsa植株体内,P1和P3的分子量分别约为27kDa和22kDa,比感染其它分离物的C. excelsa和墨西哥酸橙内的P1和P3分子量略大。P1、P2和P3的分子量与利用单克隆抗体检测的CP,CP1和CP2的分子量相等。因此,P1、P2和P3可能是CTV的外壳蛋白CP,CP1和CP2。P4的特性不清楚。研究结果也表明,利用特异性的多克隆抗体进行的Western blot是研究CTV的一种有用的技术。应用该技术,病株内不同的CTV分离物或株系就可以通过特异性蛋白条带区分开来。 相似文献
15.
ABSTRACT Genetic markers amplified from three noncontiguous regions by sequence specific primers designed from the partial or complete genome sequences of Citrus tristeza virus (CTV) isolates T3, T30, T36, and VT were used to assess genetic relatedness of 372 isolates in an international collection. Eighty-five isolates were judged similar to the T3 isolate, 81 to T30, 11 to T36, and 89 to VT. Fifty-one isolates were mixed infections by two or more identifiable viral genotypes, and 55 isolates could not be assigned unequivocally to a group defined by marker patterns. Maximum parsimony analysis of aligned marker sequences supported the grouping of isolates on the basis of marker patterns only. Specific disease symptoms induced in select citrus host plants were shared across molecular groups, although symptoms were least severe among isolates grouped by markers with the T30 isolate and were most severe among isolates grouped by markers with the T3 isolate. Isolates assigned the same genotype showed variable symptoms and symptom severity. A classification strategy for CTV isolates is proposed that combines genetic marker patterns and nucleotide sequence data. 相似文献
16.
微波诱变选育高效溶磷木霉菌株的研究 总被引：1，自引：0，他引：1
为了获得高效溶磷菌株,对木霉菌T6菌株进行微波诱变处理,测定并分析了微波输出功率和辐照时间等参数对诱变效果的影响。结果表明:最佳诱变条件是微波输出功率900 W,辐照时间70 s,且在此条件下得到8株具有较高溶磷能力的突变菌株T6-9、T6-33、T6-93、T6-126、T6-157、T6-188、T6-196和T6-203。经过多代转接培养最后得到一株遗传稳定的溶磷木霉菌株T6-157,该菌株在液体培养条件下溶磷量为204.46 mg·L~(-1),与出发菌株相比,溶磷量提高了107.97%,植酸酶活性提高了57.35%,且突变菌株对土传植物病原菌的拮抗能力也有所提高。 相似文献
17.
ABSTRACT Snow molds are psychrophilic fungi that grow under snow cover by taking advantage of carbohydrate-depleted, dormant plants. Typhula snow molds caused by Typhula incarnata, T. phacorrhiza, and T. ishikariensis are the most important winter diseases of perennial grasses and winter cereals in the United States. Colonized turfgrass samples with sclerotia were collected from 135 golf courses in Wisconsin, Utah, Michigan, and Minnesota in spring 2001 and 2002. Species and varieties from a total of 2,864 samples were identified using Typhula spp.-specific polymerase chain reaction markers. All three species were found throughout the states sampled, except T. phacorrhiza, which was not found in Minnesota. T. incarnata was distributed in areas of shorter snow cover duration and higher mean temperature than T. ishikariensis. Canonical correspondence analysis indicated that snow cover days and mean temperature were significantly correlated with frequency of Typhula spp. and T. ishikariensis varieties infecting turfgrasses on golf courses in Wisconsin, and that T. incarnata, T. phacorrhiza, and T. ishikariensis were ecologically distinct based on the 2001 data. However, because these two variables accounted for a relatively small proportion of total variation, other environmental variables also may be important in characterizing the distribution of these pathogens and require further study. 相似文献
18.
在室内采用选择性方法 ,研究了甘蓝夜蛾赤眼蜂G品系和F品系对我国几种重要农业害虫的寄主选择性。结果表明 ,G品系对亚洲玉米螟卵和麦蛾卵的选择性无明显差异 ;在对玉米螟卵的选择性上 ,G品系与玉米螟赤眼蜂的差异不明显 ,可作为防治亚洲玉米螟的候选蜂种。F品系对麦蛾卵的选择性强 ,已丧失对玉米螟卵的选择性。G和F品系以及螟黄赤眼蜂对棉铃虫卵的选择性较强 ,而对麦蛾卵的选择性较弱。在对棉铃虫卵的寄主选择性上 ,G和F品系同螟黄赤眼蜂无显著差异 ;但在寄生能力上 ,G和F品系均显著高于螟黄赤眼蜂 ,均可作为防治棉铃虫的候选蜂种。G和F品系以及广赤眼蜂对麦蛾卵的选择性较强 ,而对小菜蛾卵的选择性较弱。 相似文献
19.
Mohammad Reza Ojaghian 《Phytoparasitica》2011,39(2):185-193
Sixteen isolates belonging to 11 species of Trichoderma (T. asperellum, T. ceramicum, T. andinensis, T. orientalis, T. atroviride, T. viridescens, T. brevicompactum, T. harzianum, T. virens, T. koningii and T. koningiopsis) were evaluated for biological control of potato (Solanum tuberosum) stem rot caused by Sclerotinia sclerotiorum. In dual culture tests, all antagonists significantly reduced sclerotia formation, and were able to inhibit radial growth
of the pathogen. Growth inhibition by production of volatile and non-volatile inhibitors was also measured in in vitro tests. In screening the most efficient species of Trichoderma, establishment of mycelium on sclerotia and sclerotia lysis were also considered as important biocontrol qualities. Excluding
T. asperellum, T. brevicompactum, T. andinensis and T. harzianum, all tested Trichoderma species were able to lyse sclerotia. The sclerotia-destroying species of Trichoderma and one isolate of Talaromyces flavus were tested in greenhouse tests and during 2 years of field experimentation during the 2007 and 2008 cropping seasons. After
one aerial application of spore suspension in greenhouse trials, T. koningii, T. virens, T. ceramicum and T. viridescens were the most effective bio-agents and reduced significantly disease severity, and the least biocontrol efficacy was observed
in T. flavus. Under field conditions and after five soil and foliar applications of spore suspension, all tested antagonists reduced significantly
disease incidence. T. viridescens followed by T. ceramicum showed the best results. T. flavus and T. orientalis were less effective than other tested antagonists in both field trials. 相似文献
20.
ABSTRACT Isolates of Tilletia controversa and T. bromi were sampled from wheat and two Bromus species hosts, respectively, in the Pacific Northwest, and genetic variation within and among populations was determined. Fifty-one random amplified polymorphic DNA markers from eleven primers were treated as phenotypic 1 and 0 character state data to estimate similarities and analyze molecular variance (AMOVA) among populations and as putative genetic loci to carry out analyses of gene diversity. Phenotypic analysis of T. controversa and T. bromi isolates revealed two distinct clusters that were 37% similar. The T. bromi cluster was subdivided further into two groups, corresponding to host, with 40% similarity. Cluster analysis based on allele frequencies produced similar results and also supported two T. bromi groups based on host. No evidence of natural hybridization and introgression was detected between the T. controversa and T. bromi populations. Both AMOVA and gene diversity analyses detected moderate levels of differentiation among T. controversa populations, whereas T. bromi populations were highly differentiated. The level of genetic differentiation observed between the T. bromi populations on different Bromus species hosts supports the hypothesis that a high degree of host specificity exists in the wild grass-infecting smuts. We speculate that the higher level of genetic differentiation among the T. bromi populations compared with the T. controversa populations on wheat may be due to selection by a more genetically diverse host population. 相似文献