Piriformospora indica protects barley from root rot caused by Fusarium graminearum

Journal of Plant Diseases and Protection - The beneficial endophytic fungus Piriformospora indica colonizes barley (Hordeum vulgare L.) roots, which results in protection against diseases and...     

Influence of aldicarb on root lesion nematodes, leaf disease and root rot in wheat and barley

The effects of aldicarb on populations of root lesion nematodes (primarily Pratylenchus penetrans ) and on grain yields of spring barley and wheat were examined in the field over 3 years, 1981*83. The incidence of barley net blotch ( Pyrenophora teres ), wheat leaf blotch ( Leptosphaeria nodorum ), and common root rot ( Cochliobolus sativus ) was also recorded in 1982 and 1983. Aldicarb treatments reduced the size of root lesion nematode populations in soil and roots in all years, except in the mid-season soil sample in 1983. The severity of leaf disease was decreased only in 1982, but the incidence of root rot was not significantly affected by the nematticide. Although aldicarb increased cereal grain yields by approximately 15% there was no significant relationship between numbers of root lesion nematodes in roots and soil and fungal disease symptoms on barley and wheat.     

Fusarium species and chemotypes associated with fusarium head blight and fusarium root rot on wheat in Sardinia

Environmental conditions in Sardinia (Tyrrhenian Islands) are conducive to fusarium root rot (FRR) and fusarium head blight (FHB). A monitoring survey on wheat was carried out from 2001 to 2013, investigating relations among these diseases and their causal agents. FHB was more frequently encountered in the most recent years while FRR was constantly present throughout the monitored period. By assessing the population composition of the causal agents as well as their genetic chemotypes and EF‐1α polymorphisms, the study examined whether the two diseases could be differentially associated to a species or a population. Fusarium culmorum chemotypes caused both diseases and were detected at different abundances (88% 3‐ADON, 12% NIV). Fusarium graminearum (15‐ADON genetic chemotype) appeared only recently (2013) and in few areas as the causal agent of FHB. In F. culmorum, two haplotypes were identified based on an SNP mutation located 34 bp after the first exon of the EF‐1α partial sequence (60% adenine, 40% thymine); the two populations did not segregate with the chemotype but the A‐haplotype was significantly associated with FRR in the Sardinian data set (P = 0·001), suggesting a possible fitness advantage of the A‐haplotype in the establishment of FRR that was neither dependent on the sampling location nor the sampling year. The SNP determining the Sardinian haplotype is distributed worldwide. The question whether the A‐haplotype segregates with characters facilitating FRR establishment will require further validation on a specifically sampled international data set.     

Infection processes and soft wheat response to root rot and crown rot caused by Fusarium culmorum

An isolate of the fungus Fusarium culmorum constitutively expressing green fluorescent protein was used to investigate the infection process and host response of primary seedling roots and stem base leaf sheaths of soft wheat cv. Genio. Disease progress was assessed macroscopically by visual symptoms, microscopically by confocal laser scanning microscopy (CLSM) and via gene expression analysis of fungal and wheat genes by real‐time quantitative RT‐PCR. In the roots, CLSM investigations revealed an initial intercellular and subsequent intracellular colonization by fungal hyphae. The fungus invaded the rhizodermal layer and cortex but was not seen to colonize the stele. The fungus consistently expressed TRI5 (24, 48 and 96 h post‐inoculation), indicating that trichothecenes were being synthesized throughout this phase of infection and colonization. The expression of the six host defence‐associated genes (Wheatwin 1‐2, PR1, Chitinase, PAL, WIR1 and LOX) increased early in infection and decreased during later stages. In the stem base, CLSM observations revealed the fungus sequentially penetrating though the first, second and third basal leaf sheaths. Expression of TRI5 was initiated early in the infection of each leaf sheath. The expression of the host defence‐associated genes varied over time and across leaf sheaths, and all were also expressed in leaf sheaths which had not yet been in contact with the fungus. Expression of LOX and WIR1 were particularly enhanced in the third leaf sheath.     

Fusarium commune associated with wilt and root rot disease in rice

Wilt and root rot disease in plants has been caused mainly by Fusarium species. Previous studies reported that members of the Fusarium oxysporum species complex (FOSC) were usually associated with this disease, but there has been no report of it being caused in rice by specific Fusarium species. However, in this study, Fusarium commune was identified and characterized as a causal agent of wilt and root rot disease of rice. Four Fusarium isolates (BD005R, BD014R, BD019R, and BD020R) were obtained from different parts (root, stem, and seeds) of diseased rice plants. In morphological studies, these isolates produced key characteristics of F. commune, such as long and slender monophialides, polyphialides, and abundant chlamydospores. In molecular studies, the isolates were identified as F. commune based on sequences of the translation elongation factor 1-α (TEF1) gene that had 99.7%–100% sequence identity with the reference strain F. commune NRRL 28058. The phylogenetic tree showed that all four isolates belonged to the F. commune clade. A mating type test determined that three isolates carried MAT1-2. Their teleomorph stage was still unknown. Pathogenicity assays showed that all the isolates produced wilt and root rot symptoms and the isolate BD019R was observed as the most virulent among the isolates. To our knowledge, this is the first report of F. commune causing wilt and root rot disease on rice.     

Fusarium crown and root rot of tomatoes in the UK

Fusarium crown and root rot caused by Fusarium oxysporum f. sp. radicis-lycopersici was found in the UK in 1988 and 1989 mainly in rockwool-grown tomato crops. Up to 14% of plants were affected in individual crops. In experiments, leaf and stem symptoms did not appear until the time of first fruit harvest even when the plants were inoculated at planting, first flowers or fruit set. Conidial inoculum at 10⁶ spores/plant applied at seed sowing killed 70–83% of tomato seedlings, whereas similar levels of inoculum applied to young plants caused root and basal stem decay, and eventually death but only after fruit harvest began. Disease incidence and symptom severity increased with inoculum concentration. Experimentally, the disease was more severe in peat- or compost-grown plants than in rockwool. Disease spread was only a few centimetres in 50 days in experimental rockwool-grown plants. All tomato cultivars tested were highly susceptible. Prochloraz-Mn was highly effective against the pathogen in vitro and controlled the disease in the glasshouse, but only when applied preventively. Non-pathogenic Fusarium oxysporum isolates and Trichoderma harzianum also reduced FCRR disease levels.     

几种杀菌剂对小麦茎基腐病的防治效果

小麦茎基腐病是小麦上重要的真菌性茎基部病害,在黄淮海冬麦区呈广泛流行态势,对我国小麦生产安全构成严重威胁.本研究评价了不同拌种剂、拔节期喷施杀菌剂以及两者结合使用对小麦茎基腐病的防治效果.药剂拌种防治结果表明:60 g/L戊唑醇FS、25 g/L咯菌腈FS和25％氰烯菌酯SC拌种处理能显著降低苗期病株率,其病株防治效果...     

Fusarium species associated with stalk rot and head blight of grain sorghum in Queensland and New South Wales,Australia

Historical records report Fusarium moniliforme sensu lato as the pathogen responsible for Fusarium diseases of sorghum; however, recent phylogenetic analysis has separated this complex into more than 25 species. During this study, surveys were undertaken in three major sorghum‐producing regions in eastern Australia to assess the diversity and frequency of Fusarium species associated with stalk rot‐ and head blight‐infected plants. A total of 523 isolates were collected from northern New South Wales, southern Queensland and central Queensland. Nine Fusarium species were isolated from diseased plants. Pathogenicity tests confirmed F. andiyazi and F. thapsinum were the dominant stalk rot pathogens, whilst F. thapsinum and species within the F. incarnatum–F. equiseti species complex were most frequently associated with head blight.     

Influence of glyphosate on Rhizoctonia and Fusarium root rot in sugar beet

This study tests the effect of glyphosate application on disease severity in glyphosate-resistant sugar beet, and examines whether the increase in disease is fungal or plant mediated. In greenhouse studies of glyphosate-resistant sugar beet, increased disease severity was observed following glyphosate application and inoculation with certain isolates of Rhizoctonia solani Kuhn and Fusarium oxysporum Schlecht. f. sp. betae Snyd. & Hans. Significant increases in disease severity were noted for R. solani AG-2-2 isolate R-9 and moderately virulent F. oxysporum isolate FOB13 on both cultivars tested, regardless of the duration between glyphosate application and pathogen challenge, but not with highly virulent F. oxysporum isolate F-19 or an isolate of R. solani AG-4. The increase in disease does not appear to be fungal mediated, since in vitro studies showed no positive impact of glyphosate on fungal growth or overwintering structure production or germination for either pathogen. Studies of glyphosate impact on sugar beet physiology showed that shikimic acid accumulation is tissue specific and the rate of accumulation is greatly reduced in resistant cultivars when compared with a susceptible cultivar. The results indicate that precautions need to be taken when certain soil-borne diseases are present if weed management for sugar beet is to include post-emergence glyphosate treatments.     

Genetic variation in Fusarium avenaceum causing root rot on field pea

Isolates of Fusarium spp. were recovered from the roots of field pea (Pisum sativum) collected from 15 commercial fields in Alberta, Canada. Most of the isolates (75 out of 96) were identified as F. avenaceum, based on morphology, phylogeny and species‐specific PCR amplification. Molecular differences in the F. avenaceum isolates were detected based on putative mating type, and on ITS and CPN60 sequences. MAT‐1 and MAT‐2 were equally distributed among the isolates. Phylogenetic analysis based on ITS and CPN60 sequences clustered most of the F. avenaceum isolates into a single group. In some cases, isolates with low aggressiveness clustered together in additional groups. There was no correlation between phylogenetic profile and either mating type or geographic origin. This population of F. avenaceum has a low level of genetic variation and consists of isolates derived from the two mating types. Isolates with low aggressiveness are also retained in the population.     

2013-2016年河南省小麦茎基腐病的发生危害情况及特点

2013-2016年连续4年对河南省不同类型麦田小麦茎基腐病发生和危害情况等进行了调查。结果表明,小麦茎基腐病在河南省已经广泛分布,每年均都有不同程度发生,其中2013年病田率为45.8%,病田白穗率为0.4%~11%;2014年病田率为12.6%,病田白穗率为0.1%~3.7%;2015年病田率为32.5%,病田白穗率为0.1%~16.1%;2016年发生最重,病田率为65.1%,病田白穗率为0.1%~31.5%。调查还发现,河南省小麦茎基腐病发生的特点是北部和西部发生较重;小麦-玉米连作田发生较重,而小麦-水稻连作田块发生较轻;干旱的田块发生危害重。病害产量损失的初步测定结果表明,感病最严重的分蘖病茎高度减少55.8%,且不能结实;能结实病茎较健茎高度减少14.0%~18.0%,穗粒数减少22.7%~54.5%,穗粒重减少33.3%~90.5%,千粒重减少3.2%~73.2%;当病田白穗率为22%时,有效穗数减少33.3%,产量损失达51.6%。本文还针对目前国内对小麦茎基腐病研究薄弱的问题,提出了今后需要加强的研究工作。     

Trichothecene production is detrimental to early root colonization by Fusarium culmorum and F. graminearum in fusarium crown and root rot of wheat

Fusarium culmorum (Fc) and F. graminearum (Fg) belong to the predominant causal agents of fusarium crown and root rot (FCR) in wheat. While many studies have been done to investigate crown rot, including stem base infection, root colonization and mycotoxin production associated with root rot is not well understood. In this study the impact of mycotoxins on the colonization of wheat roots and stem bases was analysed by using Fc and Fg isolates that varied in both quantity and types of trichothecenes they produce. Seedling inoculations in growth chambers with a high deoxynivalenol (DON)- and 3-acetyldeoxynivalenol (3ADON)-producing isolate led to more severe symptoms and 20-times greater colonization of the stem base, as measured by Fc DNA accumulation, than isolates that produced less DON/3ADON. In contrast to stem base colonization, in vitro inoculations of roots with a Tri5 deletion mutant deficient in Fg trichothecene production led to three-times higher colonization than the wildtype. Furthermore, an Fc isolate that produced low levels of zearalenone resulted in twice the level of colonization of a high DON/3ADON-producing isolate included in the study. When root inoculation with a low DON/3ADON-producing Fc isolate was supplemented with exogenous DON, DON production decreased by more than half per unit weight of Fc DNA, and root colonization doubled compared to the untreated control. Therefore, in contrast to its potential role as an aggressiveness factor in stem base infection, trichothecene production by Fc and Fg is detrimental to the early stages of wheat root colonization in FCR.     

我国小麦茎基腐病菌致病力比较分析

为明确我国不同种、地理来源和毒素化学型小麦茎基腐病菌的致病力分化情况,采用纸塔法对来自全国9个省市80个采样点分离的224株小麦茎基腐病菌进行致病力分析。结果表明,不同种镰刀菌的致病力不同,黄色镰刀菌Fusarium culmorum,禾谷镰刀菌F.graminearum,假禾谷镰刀菌F.pseudograminearum及亚洲镰刀菌F.asiaticum致病力强于其他种。F.culmorum致病力显著高于F.pseudograminearum和F.asiaticum,而F.pseudograminearum,F.graminearum及F.asiaticum三者之间无显著性差异。中华镰刀菌F.sinensis,木贼镰刀菌F.equiseti,锐顶镰刀菌F.acuminatum致病力较弱,三者间苗期致病力无显著性差异;多数省份F.pseudograminearum群体间致病力无显著差异,仅山东F.pseudograminearum群体的致病性显著低于河南群体;此外,产毒类型为3ADON的F.pseudograminearum群体致病力显著高于15ADON群体。     

青稞微座孢根腐病病原鉴定

<正>青稞(Hordeum vulgare L. var. nudum Hook.f.)是大麦的一个变种,在马其顿、澳大利亚、加拿大西部和美国北部大平原等国家均有分布。国内主要分布在西藏、甘肃、青海、云南、四川等省的高海拔地区,粮饲兼用~([1])。青稞富含多种氨基酸、膳食纤维、维生素、β-葡聚糖以及钙、镁、磷、锌、锰、硒等矿质元素,在降低血脂、增加胃动力、防治高原     

青稞微座孢根腐病病原鉴定

Naked barley (Hordeum vulgare L. var. Nudum Hook.f.) is a specific food and forage crop of Qinghai-Tibet plateau in China. In June and August 2016, a root rot was found on naked barley in Qinghai Province, China. The pathogen was isolated and purified, and the four isolated strains were identified as Microdochium bolleyi by morphological and molecular methods and pathogenicity determination. As far as we know, this is the first report of M. bolleyi causing root rot on naked barley in China. Therefore, it is necessary to prevent this di-sease from spreading over a large area by adopting disease management practices so as to maintain the ecosystem.     

Biocontrol of seedling diseases of barley and wheat caused by Fusarium culmorum and Bipolaris sorokiniana: effects of selected fungal antagonists on growth and yield components

The purpose of this study was to verify, under natural conditions, biological control effects obtained in a former screening programme against Fusarium culmorum. The most successful antagonists against seedborne Fusarium culmorum and Bipolaris sorokiniana were isolates of Chaetomium sp., Idriella bolleyi and Gliocladium roseum. These results were also obtained when the antagonists were applied to B. sorokiniana-infected barley sown in field soil in pots. In field experiments, G. roseum gave the best control of F. culmorum in winter wheat. One month after sowing, germination increased by 170%, the disease index decreased by 73% and plant dry weight increased by 25%, compared to untreated plots. At harvest, the number of tillers per row was found to have increased by 53%, yield had increased by 160% and the 1000-grain weight had increased by 4%. For all evaluated parameters the effect was significantly different from the untreated plots and not significantly different from the plots treated with the fungicide, Sibutol LS 280. I. bolleyi gave a lower but still significantly effective control, when evaluated for disease index and numbers of tillers per row, while Chaetomium sp. did not show any reduction in the disease. Furthermore, in field experiments using barley infected with B. sorokiniana , a significant effect of G. roseum was demonstrated as increased plant dry weight after 1 month and increased 1000-grain weight at harvest. The disease-controlling effect of G. roseum on F. culmorum was shown in a field experiment with spring barley.     

Identification of Berkeleyomyces rouxiae causing black root rot disease on cotton seedlings in New South Wales,Australia

Black root rot disease of cotton seedlings caused by Thielavioposis basicola was first reported in New South Wales (NSW), Australia in 1990. In 2018, T. basicola was reclassified into a new genus Berkeleyomyces, accommodating two closely related species: B. basicola and B. rouxiae. However, species status of cotton-T. basicola in NSW remains unsolved. Ninety-five isolates recovered from black root rot diseased cotton seedlings sampled across NSW in 2017/18 season was subjected to morphological, multigene sequencing (ITS, MCM7, RPB2), and pathogenicity assessments for their species identification. Berkeleyomyces rouxiae was accurately identified as the causal agent of black root rot of cotton.

     

The occurrence of Fusarium crown and root rot of tomato in Israel

Based upon symptomatology and the results of pathogenicity tests, it has been shown that the Fusarium crown and root rot organism of tomato — previously reported only from North America and Japan — is present in Israel.     

Effect of the fungal pathogen Bipolaris sorokiniana toxin prehelminthosporol on barley root plasma membrane vesicles

The effects of the phytotoxin prehelminthosporol from the fungal pathogen Bipolaris sorokiniana on the activities of the plasma membrane H⁺-ATPase, Ca²⁺- ATPase, and 1, 3-β-glucan synthase in barley roots were investigated in vitro. Plasma membranes were isolated by aqueous polymer two-phase partitioning. Proton pumping by the H⁺-ATPase was drastically reduced in a dose-dependent manner, with complete inhibition at 500 μM prehelminthosporol, while inhibition of ATP hydrolysis was less drastic, with a 35% inhibition at 500 μM toxin. Ca²⁺ uptake was also reduced, although to a lesser extent than proton pumping, with a maximal inhibition of 60% at 500 μM toxin. The 1, 3-β-glucan synthase activity was weakly stimulated at toxin concentrations below 100 μM, with higher concentrations being inhibitory. Taken together, our results indicate that prehelminthosporol exerts its effect in at least two ways. First, it appears to disrupt the membrane barrier and thus seriously interfere with establishment of the proton gradient that drives ion and nutrient uptake and affect the efflux of Ca²⁺ to maintain the low cytoplasmic concentration of Ca²⁺ essential for the function of Ca²⁺ as a messenger in signal transduction. Secondly, it appears to inhibit the enzyme activities. The 1, 3-β-glucan synthase is activated by Ca²⁺ and can operate in the presence of low concentrations of prehelminthosporol (which may induce Ca²⁺ leakage into the cytoplasm and hence activate the enzyme), to produce callose to seal leaky membranes.