Fine-mapping of a candidate gene for web blotch resistance in Arachis hypogaea L.

Peanut(Arachis hypogaea L.)is a globally important oil crop.Web blotch is one of the most important foliar diseases affecting peanut,which results in serious yield losses worldwide.Breeding web blotch-resistant peanut varieties is the most effective and economically viable method for minimizing yield losses due to web blotch.In the current study,a bulked segregant analysis with next-generation sequencing was used to analyze an F2:3 segregating population and identify candidate loci related to web blotch resistance.Based on the fine-mapping of the candidate genomic interval using kompetitive allele-specific PCR(KASP)markers,we identified a novel web blotch resistance-related locus spanning approximately 169 kb on chromosome 16.This region included four annotated genes,of which only Arahy.35VVQ3 had a non-synonymous single nucleotide polymorphism in the coding region between the two parents.Two markers(Chr.16.12872635 and Chr.16.12966357)linked to this gene were shown to be co-segregated with the resistance of peanut web blotch by 72 randomly selected recombinant inbred lines(RIL),which could be used in marker-assisted breeding of resistant peanut varieties.

Screening and Identification of Antagonistic Bacterium ZG-10 against Spot Blotch Disease in Pakchoi

[ Objective] The purpose was to screen bacterium with antagonistic effect against pathogen of spot blotch disease in pakchoi in vegetable field. [Method] More than 200 strains of bacteria which could produce spore were isolated from soil in different places. Through screening and rescreening, the bacteria with higher antibacterial activity were conducted observation about thallus shapes and colony characters, a series of physiological and biochemical tests were performed. [Result] Rescreening results indicated that the strains including ZG-10, ZG-19, ZG-59, ZG-72 and ZG-31 had significant antibacterial activity, which had very high research value and good application prospect for biocontrol on spot blotch disease in pakchoi; the strain ZG-10 was identified to be Bacillus subtilis. [ Conclusion] The strain ZG-10 had biocontrol potential and good development prospect. This research laid certain basis for subsequent research and strated a new way for the application of antagonistic strain and proteinum polypeptide in agdculture.

Detection of Apple Marssonina Blotch with PLSR, PCA, and LDA Using Outdoor Hyperspectral Imaging

In this study, hyperspectral images were used to detect a fungal disease in apple leaves called Marssonina blotch(AMB). Estimation models were built to classify healthy, asymptomatic and symptomatic classes using partial least squares regression(PLSR), principal component analysis(PCA), and linear discriminant analysis(LDA) multivariate methods. In general, the LDA estimation model performed the best among the three models in detecting AMB asymptomatic pixels, while all the models were able to detect the symptomatic class. LDA correctly classified asymptomatic pixels and LDA model predicted them with an accuracy of 88.0%. An accuracy of 91.4% was achieved as the total classification accuracy. The results from this work indicate the potential of using the LDA estimation model to identify asymptomatic pixels on leaves infected by AMB.

Complete genome sequences of four isolates of Citrus leaf blotch virus from citrus in China

Citrus leaf blotch virus （CLBV） is a member of the genus Citrivirus, in the family Betaflexiviridae. It has been reported CLBV could infect kiwi, citrus and sweet cherry in China. Of 289 citrus samples from six regions of China, 15 were detected to be infected with CLBV in this study. The complete genome of four isolates of CLBV was obtained from Reikou in Sichuan （CLBV-LH）, Yura Wase in Zhejiang （CLBV-YL）, Bingtangcheng in Hunan （CLBV-BT）, Fengjie 72-1 in Chongqing （CLBV- F J）, respectively. While they all represented 8 747 nucleotides in monopartite size, excluding the poly（A） tail, each of the isolates coded three open reading frames （ORFs）. Identity of the four isolates ranged from 98.9 to 99.8% to each other and from 96.8 to 98.1% to the citrus references in GenBank by multiple alignment of genomes. A phylogenetic tree based on the genome sequences of available CLBV isolates indicated that the four isolates were clustered together, suggesting that CLBV isolates from citrus in China did not have obvious variation. This is the first report of the complete nucleotide sequences of CLBV isolates infecting citrus in China.

Development and characterization of new allohexaploid resistant to web blotch in peanut

Peanut diseases seriously threaten peanut production, creating disease-resistant materials via interspecific hybridization is an effective way to deal with this problem. In this study, the embryo of an interspecific F1 hybrid was obtained by crossing the Silihong(Slh) cultivar with Arachis duranensis(ZW55), a diploid wild species. Seedlings were generated by embryo rescue and tissue culture. A true interspecific hybrid was then confirmed by cytological methods and molecular markers. After treating seedlings with colchicine during in vitro multiplication, the established interspecific F1 hybrid produced seeds which were named as Am1210. With oligonucleotide fluorescence in situ hybridization(Oligo FISH), molecular marker evaluations, morphological and web blotch resistance characterization, we found that: 1) Am1210 was an allohexaploid between Slh and ZW55;2) the traits of spreading lateral branches, single-seeded or double-seeded pods and red seed coats were observed to be dominant compared to the erect type, multiple-seeded pods and brown seed coats;3) the web blotch resistance of Am1210 was significantly improved than that of Slh, indicating the contribution of the web blotch resistance from the wild parent A. duranensis. In addition, 69 dominant and co-dominant molecular markers were developed which could be both used to verify the hybrid in this study and to identify translocation or introgression lines with A. duranensis chromosome fragments in future studies as well.

Overview of purple blotch disease and understanding its management through chemical, biological and genetic approaches

Purple blotch disease of Allium spp. crops caused by Alternaria porri has remained a major concern in agriculture for both farmers and research fraternity as it severely damages the crops and drastically reduces the yield. The symptoms appear after 1–4 days of infection and bulb rot begin, and eventually turn into dark reddish-purple and then brownish/black lesions. Many factors like season, time of sowing, humidity and temperature, stage of crop, and plant architecture have a huge impact on the progression of purple blotch disease. Many genic markers based on amplification of an Alta1 gene sequence have been designed for identification and differentiation of different Alternaria species groups. Among the most commonly used fungicides, mancozeb, tebuconazole, difenaconazole and azoxystrobin were found to be the ideal for the management of purple blotch disease and increased garlic yield. Many biological approaches such as plant extracts and bio-control agents were found partially effective for controlling the disease. A report on QTL mapping for purple blotch resistance discovered that purple blotch resistance is controlled by a single dominant gene ApR1. To completely understand the purple blotch disease resistance for crop improvement, a study is required at transcriptome level for hunting purple blotch resistant genes by gene annotation and mining. Genetic engineering and genome editing are other approaches that can be done for engineering disease resistance in Allium crops for genetic improvement.

Application of Pyroligneous Acid in the Prevention and Control of Brown Blotch Disease in Pleurotus ostreatus

In the present study, agar diffusion test and field trials were carried out using a mushroom （Pleurotus ostreatus） culti- var Shouyanping as the experimental material to determine the antibacterial activity of refined pyroligneous acid prepared from almond shell against Pseudomonas tolaasfi and its effects on mycelial growth of mushroom. The results revealed that 1.25%, 2.50% and 5.00% of refined pyroligneous acid obviously inhibited the occurrence of brown blotch disease in mushroom, but also greatly promoted mushroom mycelial growth. Therefore, 1.25% and 2.50% of refined pyroligneous acid can be used in fields to prevent brown blotch disease, and 5.00% refined pyroligneous acid can be used to control the incidence of brown blotch disease when it widely occurs in fields.

Application of droplet digital PCR in detection of seed-transmitted pathogen Acidovorax citrulli

Bacterial fruit blotch caused by Acidovorax citrulli is a serious threat to cucurbit industry worldwide.The pathogen is seedtransmitted,so seed detection to prevent distribution of contaminated seed is crucial in disease management.In this study,we adapted a quantitative real-time PCR(qPCR)assay to droplet digital PCR(ddPCR)format for A.citrulli detection by optimizing reaction conditions.The performance of ddPCR in detecting A.citrulli pure culture,DNA,infested watermelon/melon seed and commercial seed samples were compared with multiplex PCR,qPCR,and dilution plating method.The lowest concentrations detected(LCD)by ddPCR reached up to 2 fg DNA,and 102 CFU mL–1 bacterial cells,which were ten times more sensitive than those of the qPCR.When testing artificially infested watermelon and melon seed,0.1%infestation level was detectable using ddPCR and dilution plating method.The 26 positive samples were identified in 201 commercial seed samples through ddPCR,which was the highest positive number among all the methods.High detection sensitivity achieved by ddPCR demonstrated a promising technique for improving seed-transmitted pathogen detection threshold in the future.

Breeding of a New High-yield, High-oil and Web Blotch-resistant Big Peanut Variety Shanghua 511

Shanghua 511 is a high-yield, high-oil and web blotch-resistant big peanut variety bred by the Shangqiu Academy of Agriculture and Forestry Sciences through sexual hybridization （Yuhua 18♀×Shangyan 9658♂）. In the wheat-peanut interplanting regional experiment conducted in Henan Province during 2012-2013, the average pod and seed yield of Shanghua 511 were 5906.19 and 4149.3 kg/hm2, respectively. In the wheat-peanut interplanting production experiment conducted in Henan Province in 2013, the average pod and seed yield of Shanghua 511 were 6036.45 and 4309.50 kg/hm2, respectively. In the kernels of Shanghua 511, the contents of crude fat, oleic acid and linoleic acid were 56.62%, 44.9% and 33.4% respectively, and the oleic/linoleic acid ratio was 1.34. This variety had high resistance to web blotch and medium resistance to leaf spot, viral diseases, root rot and collar rot. The 100-pod weight, 100-kernel weight, shelling percentage and growth period of Shanghua 511 were 270.6, 110.9 g, 70.6% and 120 d, respectively. Shanghua 511 passed the approval of Henan Provincial Crop Variety Approval Committee in August, 2015, and is suitable for spring sowing and wheat interplanting in the surrounding area of Henan Province and the area to the north of Huaihe River.

A Comparative Analysis of Culture Media for Optimizing the Mycelial Growth and Sporulation of Stemphylium vesicarium Cause of White Blotch of Onion

This study was conducted to identify a cheap and suitable culture medium for the mycelial growth and sporulation of Sternphylium vesicarium and to determine the cultural and morphological variability of this pathogen. A total of 24 isolates of S. vesicarium collected from eight different onion growing areas were characterized in terms of cultural and morphological aspects. Front colony colors were greenish brown to dirty white, deep grey to whitish, light grey to whitish, deep greenish white, light grey and dirty white to greenish. Reverse colony colors were brown, deep brown and light brown. Colony shapes were circular and irregular with umbonate, raised and flat type colony elevation. Colony textures were cottony, fluffy and velvety with entire, undulate and filiform type colony margin. Among the culture media, V-7 juice agar found to be the most suitable culture media for mycclial growth of S. vesicarium. The sporulation of the fungus was remarkably influenced by V-7 juice mixed with potato dextrose agar （PDA） media, this media exhibited the highest sporulation （87.76-169.0/mm^2） of S. vesicariumin comparison with other media. The minimum days （28 d to 31 d） for conidial production were observed on V-7 juice agar medium. The length of conidia varied from 14.6 μm to 30.6 μm. The maximum mean length of conidia was 29.97 μm found in isolate DSSA, while the minimum mean length 17.36 μm was found in isolate MSMM 02. The breadth of conidia ranged from 4.7 μm to 15.7μm. The maximum mean breadth of conidia was 12.55 μm found in the isolate DSSA, while the minimum mean breadth 9.760 μm was found in the isolate CCKH 02. The horizontal septation varied from l to 3 and the longitudinal septation varied from 0 to 4.

指纹光谱特征揭示叶斑病时空动态发展以实现显症前诊断

植物病原菌不断危害农业生产和粮食安全。因此,病害发展早期的动态表征对病变监测和显症前诊断至关重要。高光谱成像(HSI)在跟踪病害初始侵染部位的动态进程以进行显症前诊断方面具有巨大潜力。然而,目前尚无相关文献提取出早期感染阶段活体叶片病变组织的指纹光谱特征(FSS),也没有探究HSI的检测机制。其中FSS是指能够表征特定植物病害的独特、有代表性的光谱特征。在本研究中,基于时序HSI数据分析,提取了接种Bipolaris sorokiniana的大麦叶片的FSS,以表征叶斑病症状发展,实现显症前诊断。还研究了叶斑病早期发展阶段叶片的光谱和生化响应。本文所提取的全波段FSS能够捕捉病变发展过程中褪绿组织和坏死组织的独特特征,从而原位可视化植物-病原菌像素级的早期互作动态进程。进一步,实现了接种后24 h叶斑病的显症前诊断,比传统的聚合酶链反应(PCR)测定或生化测定提前了12 h。为了揭示HSI显症前诊断的机制,还建立了叶片的平均光谱响应与其生化指标(叶绿素、类胡萝卜素、丙二醛、抗坏血酸和还原型谷胱甘肽)之间的定量关系,回归模型在预测集上的Rp2均高于0.84。总体结果表明,HSI反映了活体植物特性的变化,所提取的FSS可成功跟踪叶斑病发生发展的时空动态进程,实现显症前诊断。在其他植物病害上的试验表明,该方法在植物病害早期控制方面具有较大的推广潜力。

<i>In-Vivo</i>Management of Purple Blotch of Onion Caused by <i>Alternaria porri</i>(Ellis) Cif. through Fungicides

An experiment was carried out to study the outcome of environmental factors (Temperature, Relative Humidity, Rainfall) and management of the purple blotch disease of onion using five treatments (Rovral + Ridoil gold with 3,4,5,6 sprays and control). The Taherpuri variety was used during the 2015-2016 cropping seasons at BARI, Gazipur, Bangladesh. In the experiment, the purple blotch disease surfaced at the end of January 2016 and was severe in late February to March (PDI 76.12%) due to temperature and RH above 24°C and 95%, respectively. As for the chemical control, the PDI for the treatments ranged from 50.66% to 83.33%. Significantly higher stem height was recorded by T4 (68.06 cm), where six sprays of Rovral + Ridomil were applied. The minimum stem height was recorded in T5 (59.23 cm). The maximum stem number per hill was recorded in T4 (2.30) numerically but differed significantly with T5 (2.00), where fungicides were not applied. The maximum lesion area was measured in T5 (25.26 mm2). Regarding PDI (Percent disease index), there was a significant difference among the treatments. The PDI value on purple blotch of onion ranged from 34.00 to 83.33. The lowest PDI was assessed in T4 (34.00). Statistical analysis revealed that a significant decrease of PDI on purple blotch was recorded under treatments of T1, T2, T3, and T4 (39.20%, 45.60%, 49.59%, and 59.19%) on controlling the disease and giving the optimum yield but all of them significantly differed with T5 (83.33%) where no fungicides were sprayed.

Differences in Aggressiveness and Morphology of Mycosphaerella graminicola Isolates Causal Agent of Septoria Tritici Blotch on Wheat

Reactions 13 wheat cultivars to 18 Mycosphaerella graminicola isolates, collected from three distinct localities, were in average different but differences among individual cultivars were small. All cultivars were susceptible to septoria tritici blotch. Reactions of wheat cultivars to M. graminicola isolates varied from 31% to 41%. Some cultivars had low differences but the other high in reactions to used isolates in average. Variance of individual cultivars to all isolates in reactions of maximal and minimal values fluctuated between 44-80%. More differences were in reactions between individual isolates to single cultivars. Aggressiveness individual isolates to all tested cultivars oscillated in average from 9% to 66% of necrotic leaf area covered by pycnidia. Three isolates had very low, whereas five isolates had high aggressiveness in average to all cultivars. Difference in maximal and minimal aggressiveness of individual isolates to all cultivars was between 13 and 60%. Avirulent reaction was ascertained in the cultivar Rexia to one isolate. Isolates showed wide differences in colored and morphological characteristics. Dissimilarity and similarity was in border shape, cultivation types, surface and coloration of isolate colony also.

The Relationship between Diseases Index of Septoria Leaf Blotch, Leaf Rust and Yield Losses in Bread Wheat Cultivar in Albania

Both grain yield and disease performance are important factors to consider for winter wheat （Triticum aestivum） cultivar selection. However, disease index and yield data are often presented separately, making it difficult to compare values across multiple environments. Two-year investigations （2009-2010）, in which eight common wheat lines/genotypes were included to test their susceptibility against wheat LR （leaf rust） Puccinia triticina f. sp. tritici Roberge ex Desm., and the SLB （SeptoriaJStagonospora leaf blotch） complex Septoria tritici Desm. and Stagonospora nodorum, were carried out in the experimental field of ATTC （Agriculture Technology Transfer Centre） of Lushnje （Albania）. The objective of this study was to use a rank-based method to compare cultivars based on yield and disease performance combined across multiple environments. Analysis of variance revealed the presence of an important and significant variability in the experimental materials used to evaluate the susceptibility and the resistance of common wheat lines against SLB and LR. There were high negative correlations between yieldS, tritici （0.6683） and yield--P, recondita f. sp. tritici （0.5261）. The negative effects of two pathogens have shown ＂the parallel＂/similar negative influences on yield trait and there was a high positive correlation （0.7631） between S. tritici and P. recondita f. sp. tritici. According to study results the lines Regina × L-776, IKB-P6 and Bullgar 3 × KB 703 have shown good results of resistance （R） level against S. tritici and P. recondita f. sp. tritici.

Typology of the Main Fungal Diseases Affecting Winter Wheat in the Grand Duchy of Luxembourg

Over the 2003-2009 period, field campaigns were carried out in order to identify the main fungal diseases of winter wheat （Triticum aestivum） in the Grand-Duchy of Luxembourg. Four fungal diseases （septoria leaf blotch （SLB）, wheat leaf rust （WLR）, wheat powdery mildew （WPM） and fusarium head blight （FHB）） were observed and a regional-based typology was established according to their severity and prevalence. In the Gutland （South）, SLB severity was strong （about 51% on average） and higher than the severity （about 16%） prevailing in the Oesling （North）. Similar typology was observed with the WLR： high severity in the Gutland （66% and 57% for the years 2003 and 2007, respectively） and low severity （〈 1%） in the Oesling. The FHB was also present in the Eastern part of the Gutland, with a prevalence and severity significantly higher （P = 0.049 and P = 0.012, respectively, Tukey＇s test） compared with their values in the Oesling. On the other hand, the WPM severity was high in the Oesling （15% to 40%） while less than 1% in the Gutland. Such a study is important for the spatial mapping of wheat fungal diseases risk based on agroclimatic parameters and for defining optimal frequencies and dates of chemical treatments.

Evaluation of Barley Genotypes for Resistance to Pyrenophora Teres Using Molecular Markers

Net blotch disease caused by the fungus Pyrenophora teres belongs to the complex of leaf blotch diseases that decrease the yield and the quality of barley （Hordeum vulgate L.）. This study deals with the use of microsatellites localized nearby the quantitative trait loci, associated with the resistance to P. teres to screen barley lines and varieties that could be introduced into a net blotch resistance breeding program. Thirty-five barley microsatellite loci and 65 barley genotypes, 265 alleles were detected. The number of alleles per locus ranged from 2 to 26. The arrangement of genotypes into clusters based on microsatellite data does not correspond to their resistance level to P. teres even though chosen microsatellite markers have been localized nearby QTLs associated with the resistance to P. teres.

Evaluation of Combined Effect of Micronutrients (ZnSO4 + Borax) and Fungicides to Control the Purple Blotch Complex of Onion (Allium cepa)

Ten different treatments viz. T0 = Control, T1 = Micronutrients (ZnSO4 + Borax), T2 = Rovral 50 WP + Micronutrients, T3 = Dithane M-45 + Micronutrients, T4 = Ridomil Gold + Micronutrients, T5 = Cupravit + Micronutrients, T6 = Rovral 50 WP, T7 = Dithane M-45, T8 = Ridomil Gold and T9 = Cupravit were evaluated against the purple blotch complex disease of onion caused by Alternaria porri and Stemphylium vesicarium in field condition for bulb yield. In lab condition, all the tested chemical fungicides (Rovral 50 WP, Dithane M-45, Ridomil Gold MZ-72 and Cupravit 50 WP) significantly reduced mycelial growth of both pathogens. Among the fungicides, Rovral 50 WP @ 0.2% reduced the highest radial mycelial growth followed by Dithane M-45 @ 0.45% and Ridomil Gold MZ-72 @ 0.2% compared to control. In field experiment, application of Rovral 50 WP @ 0.2% along with micronutrients showed significant effect in reducing disease incidence and severity which significantly increased bulb yield and yield contributing characters.

Field Control Efficacy of Three Fungicides against Eucalyptus Purple Blotch

[Objective] The paper was to explore safe fungicides with high efficiency and long persistence against eucalyptus purple blotch. [Method]10%Difenoconazole WG,500 g /L thiophanate-methyl SC and 50% carbendazim WP were evaluated through experiment in forest,and clear water was used as CK. [Result]Three fungicides all had relatively good control effect against eucalyptus purple blotch. Most eucalyptus trees were able to restore growth and sprout new shoots after continuous three times of administration with the interval of 10 d. 10% Difenoconazole WG possessed the best control effect against eucalyptus purple blotch,with the disease index of 25. 24 and the control effect of 40. 24%; followed by 500 g /L thiophanate-methyl SC 600 times dilution,with the disease index of 27. 09 and the control effect of 35. 87%; 50% carbendazim WP 500 times dilution had the poorest control effect,with the disease index of 32. 21 and the control effect of23. 74%. The disease index of CK was 42. 24. [Conclusion]The above fungicides were safe to eucalyptus,and could be used to control eucalyptus purple blotch.

Phylogeny and taxonomy of Ophiognomonia(Gnomoniaceae,Diaporthales),including twenty-five new species in this highly diverse genus

Species of Ophiognomonia are leaf-inhabiting endophytes,pathogens,and saprobes that infect plants in the families Betulaceae,Fagaceae,Juglandaceae,Lauraceae,Malvaceae,Platanaceae,Rosaceae,Salicaceae,and Sapindaceae.Based on extensive collecting,this speciesrich genus is now known to have a world wide distribution in primarily temperate areas,although some species are known from the subtropics.Analyses of DNA sequences from three markers including guanine nucleotide-binding protein subunit beta-like protein(MS204),translation elongation factor 1α(tef-1α),and the ITS region including ITS1,5.8 S rDNA and ITS2 regions(ITS)were used to define phylogenetic species in Ophiognomonia.Host plant association correlated with these species.Twenty-five new species of Ophiognomonia and two new combinations are proposed with descriptions and illustrations.In addition,descriptions and illustrations are provided for 12 other species of Ophiognomonia.A key is provided to the 45 currently accepted species of Ophiognomonia.The disposition of additional names in Ophiognomonia is also discussed.

Epidemiological factors of septoria tritici blotch(Zymoseptoria tritici)in durum wheat(Triticum turgidum)in the highlands of Wollo,Ethiopia

Background:Septoria tritici blotch(STB)(Zymoseptoria tritici)is a major disease of durum wheat,an economic crop grown in the highlands of Wollo in Ethiopia.Methods:To determine the status of this disease,we conducted surveys in five districts of Wollo(Meket,Woreilu,Wadila,Jama,and Dessie Zuria)during the 2015 cropping season.We visited 75 farm plots to determine the prevalence,incidence,and severity of STB.Results:STB prevalence varied among locations,genotypes,planting dates,growth stages,previous crops,plant population,weed population,and soil types.Similarly,disease intensity also varied along all independent variables.The level of incidence was high in all the visited districts,and the level severity ranged from 9.9 to 59.3%while the incidence varied from 50 to 100%.The mean differences in incidence and severity within the districts’variable classes,altitude,varieties,growth stage,plant population,planting date,previous crop,weed population,and soil type were high.The independent variables,districts,altitude,varieties,growth stage,plant population,planting date,previous crops,weed population,and soil type,were significantly associated with high incidence and severity of STB as single predictor in the logistic regression model.A reduced multiple variable model was fitted using districts,altitude,varieties,growth stage,plant population,planting date,previous crop,weed population,and soil type as independent variables.High incidence(>50%)and severity(>25%)had a high probability of association to all independent variables,except previous crop.Low disease incidence(≤50%)and low disease severity(≤25%)had high probability of association to the previous crop.Conclusion:Environmental variables,cultivation practice,and responses were important for the development of STB.Therefore,these factors must be considered in designing strategies for the effective management of STB.