Screening of Promising Genotypes of Isabgol against Downy Mildew Disease (Peronospora plantaginis)

Isabgol (Plantago ovata) is an important Rabi crop grown in dry regions of India. It plays an important role in reducing stomach disorders. The crop of Isabgol suffers with number of diseases. Downy mildew disease of Isabgol caused by Peronospora plantaginis is one of the wide spread and destructive diseases in India. The symptoms of downy mildew of Isabgol appear 30-35 days after sowing. As the disease progressed, the leaves become necrotic and started drying from the tip to backward and plant become stunted. The genotype screening is an eco-friendly method for management of plant diseases; hence an experiment was conducted to identify the resistant genotypes against downy mildew of Isabgol under natural field condition. Out of 36 genotypes, 8 genotypes were found resistant, 15 genotypes were found moderately resistant, 8 genotypes were found moderately susceptible and 5 genotypes were found susceptible against downy mildew of Isabgol.

Screening of Pearl Millet Lines against Downy Mildew Incited by Sclerospora graminicola (Sacc.) J. Schrot in Madhya Pradesh, India

Pearl millet (Pennisetum glaucum L.) is the oldest cultivated crop prone to attack by many pathogens viz., Sclerospora graminicola, Moesziomyces penicillariae and Puccinia substriata. The present investigation is on the management of the downy mildew pathogen by exploiting the resistance mechanism of the host. Out of 163 lines and two checks were tested against downy mildew disease. The germplasms were screened in the downy mildew sick plot. The finding exposes that 40 lines were never present of downy mildew and another 68 lines showed < 5% and > 10% downy mildew incidence was recorded in 23 lines and remaining 33 lines were recorded in the category of 5-10% incidence, while a maximum of 83.27 and 97.05% downy mildew incidence was noted in 7042-S at 30 and 60 days after sowing. When compared to all the test lines, the susceptible check 7042-S showed considerably greater incidence of downy mildew at 30 and 60 days. The present investigation suggests that the resistance in the Pearl millet germplasms can be exploited for the management of the pathogens and is an effective management practice with less use of inputs.

Perspective, Challenges for Biological and Chemical Management of Important Diseases of Mungbean (Vigna radiata L.): A Review

Use of biological agents and fungicides like- T. viride at 2.5%, T. harzianum @ 2.5% and Pseudomonas fluorescens @ 2%, neem leaf extract at 10%, garlic extract at 10%, and carbendazim at 0.1% as a fungicide in powdery mildew disease for give the better results compare to control. A germplasms lines of mungbean were tested for resistance to Macrophomina phaseolina along with JL-781 as a susceptible check in sick plots these test lines. Among the 2 were moderate resistant, 1 germplasm was moderate susceptible, 1 germplasm was susceptible and JL-781 to highly susceptible. A visual scoring index (VSI) was used to evaluate the signs and symptoms of MYMV infection. Compared to the primed plants, which only had 14% of the same symptoms, more than 70% of the unprimed plants had symptoms that were considered serious or deadly. Whitefly control with insecticides has been deemed helpful for managing yellow mosaic virus. The environment and human health were also negatively impacted by the over usage of chemicals. Preventive and therapeutic measures using pesticides effectively is crucial for preventing soil-dwelling and seed-borne infections across all IDM strategies. All of the fungicides outperformed traditional fungicides in terms of performance.

Progression of Powdery Mildew of Indian Mustard (Brassica juncea L.) in Relation to Weather Parameters

The work entitled “Progression of powdery mildew of Indian mustard (Brassica juncea L.) in relation to weather parameters” was carried out in Agriculture Research Farm, Banda University of Agriculture & Technology, Banda, Uttar Pradesh, India during Rabi 2020-21 season. As infection and development of a disease depends on the favourable environmental conditions hence, relationship between powdery mildew of Indian mustard and weather factors was evaluated in Ganga, Varuna, Giriraj and RH-0749 varieties of Indian mustard in which maximum temperature between 25-30°C, minimum temperature >10°C with minimum relative humidity (RH) <50% favoured the development of powdery mildew in all the four varieties Indian mustard varieties. Individual and combined effects of different weather parameters on development of powdery mildew was evaluated using correlation and regression analysis. Percent disease index (PDI) of powdery mildew was positively correlated with the maximum and minimum temperature whereas, it was negatively correlated with maximum RH, minimum RH and rainfall in Indian mustard varieties Ganga, Varuna, Giriraj and RH-0749. Coefficient of determination (R2) explained that 96, 96, 95 and 96 % powdery mildew development was influenced by the maximum temperature, minimum temperature, maximum relative humidity, minimum relative humidity and rainfall in Indian mustard varieties Ganga, Varuna, Giriraj and RH-0749, respectively. Multiple linear regression equation was developed to find out the expected PDI of the disease based on the predictor weather variables. Correlation analysis explained that warmer temperature and lesser humidity favoured the development of powdery mildew in Indian mustard. Multiple linear regression model developed in current investigation may be utilized for development of powdery mildew prediction model in Indian mustard.

Screening of Mustard Germplasm against Powdery Mildew (Erysiphe cruciferarum) and Analysis of Yield Contributing Characters

The current experiment was carried out at the Regional Agricultural Research Station (RARS) Polasa, Jagtial during rabi 2020-21, with the goals of (1) assessing the resistance of Indian mustard germplasm lines to powdery mildew disease and (2) analysing the yield and its contributing traits, days to 50% flowering, days to maturity, plant height in centimetres, primary branch number, secondary branch number, siliqua number and siliqua length in centimetres. The results of the analysis of variance showed that there were statistically significant differences between the genotypes and their characteristics. The genotypes viz., DRMR-150-35, Black gold, and RH-9304 performed best on average out of 50 different varieties for twelve different characteristics, including high seed yield per plant, high 1000-seed weight and high harvest index.Two resistant genotypes (GM-3 and Swarna Jyothi) and nine genotypes (Pusa mahak, PM-25, PM-26, PDZM-31, Pusa tarak, Pusa bahar, Ashirwad, DRMR-601, and JM-2) demonstrated considerable resistance reaction to the powdery mildew disease after being screened against the illness. We can solve the disease effect problem by utilizing these germplasm lines as donors in future breeding programme to develop powdery mildew resistant lines.

Establishment of a fast discriminant model with electronic nose for Polygonati Rhizoma mildew based on odor variation / 中国中药杂志

The odor fingerprint of Pollygonati Rhizoma samples with different mildewing degrees was analyzed and the relationship between the odor variation and the mildewing degree was explored. A fast discriminant model was established according to the response intensity of electronic nose. The α-FOX3000 electronic nose was applied to analyze the odor fingerprint of Pollygonati Rhizoma samples with different mildewing degrees and the radar map was used to analyze the main contributors among the volatile organic compounds. The feature data were processed and analyzed by partial least squares discriminant analysis(PLS-DA), K-nearest neighbor(KNN), sequential minimal optimization(SMO), random forest(RF) and naive Bayes(NB), respectively. According to the radar map of the electronic nose, the response values of three sensors, namely T70/2, T30/1, and P10/2, increased with the mildewing, indicating that the Pollygonati Rhizoma produced alkanes and aromatic compounds after the mildewing. According to PLS-DA model, Pollygonati Rhizoma samples of three mildewing degrees could be well distinguished in three areas. Afterwards, the variable importance analysis of the sensors was carried out and then five sensors that contributed a lot to the classification were screened out: T70/2, T30/1, PA/2, P10/1 and P40/1. The classification accuracy of all the four models(KNN, SMO, RF, and NB) was above 90%, and KNN was most accurate(accuracy: 97.2%). Different volatile organic compounds were produced after the mildewing of Pollygonati Rhizoma, and they could be detected by electronic nose, which laid a foundation for the establishment of a rapid discrimination model for mildewed Pollygonati Rhizoma. This paper shed lights on further research on change pattern and quick detection of volatile organic compounds in moldy Chinese herbal medicines.

Cucumber downy mildew and the mechanisms of host resistance: a review / 生物工程学报

The cultivation and production of cucumber are seriously affected by downy mildew caused by Pseudoperonospora cubensis. Downy mildew damages leaves, stems and inflorescences, and then reduces the yield and quality of cucumber. This review summarized the research advances in cucumber downy mildew, including pathogen detection and defense pathways, regulatory factors, mining of pathogens-resistant candidate genes, proteomic and genomic analysis, and development of QTL remarks. This review may facilitate clarifying the resistance mechanisms of cucumber to downy mildew.

High-speed identification of odor changes and substance basis of Myristicae Semen mildew by electronic nose and HS-GC-MS / 中国中药杂志

This study adopted headspace-gas chromatography-mass spectrometry(HS-GC-MS) and electronic nose to detect volatile components from Myristicae Semen samples with varying degrees of mildew, aiming at rapidly identifying odor changes and substance basis of Myristicae Semen mildew. The experimental data were analyzed by electronic nose and principal component analysis(PCA). The results showed that Myristicae Semen samples were divided into the following three categories by electronic nose and PCA: mildew-free samples, slightly mildewy samples, and mildewy samples. Myristicae Semen samples with different degrees of mildew greatly varied in volatile components. The volatile components in the samples were qualitatively and quantitatively detected by HS-GC-MS, and 59 compounds were obtained. There were significant differences in the composition and content in Myristicae Semen samples with different degrees of mildew. The PCA results were the same as those by electronic nose. Among them, 3-crene, D-limonene, and other terpenes were important indicators for the identification of mildew. Bicyclo[3.1.0]hexane, 4-methylene-1-(1-methylethyl)-, terpinen-4-ol, and other alcohols were key substances to distinguish the degree of mildew. In the later stage of mildew, Myristicae Semen produced a small amount of hydroxyl and aldehyde compounds such as acetaldehyde, 2-methyl-propionaldehyde, 2-methyl-butyraldehyde, and formic acid, which were deduced as the material basis of the mildew. The results are expected to provide a basis for the rapid identification of Myristicae Semen with different degrees of mildew, odor changes, and the substance basis of mildew.

QTL identification for downy mildew resistance in cucumber using genetic linkage map based on SSR markers

Fourteen cucumber lines were tested for genetic homozygosity and performed pairwise comparison to identify a pair with the highest DNA polymorphic level. Cucumber accessions CSL0067 and CSL0139 were selected to generate 315 F2 populations. The genetic linkage map based on 66 polymorphic SSR markers was constructed. It composed of eight linkage groups (LGs) spanning 474.4 cM. Downy mildew disease reaction was evaluated in cotyledons, first and second true leaf on 7, 10, and 14 day after inoculation. The results showed that downy mildew resistance was controlled by multiple recessive genes. The susceptible to resistant ratio of F2 progenies fit 9:7 susceptible/resistant segregation types corresponding to duplicate recessive epistasis. Fourteen QTLs were detected. The phenotypic variance ranged from 5.0 to 12.5%, while LOD values ranged from 3.538 to 9.165. Two major QTLs and two QTL hotspots were identified. Moreover, the additive effects data explained that these QTL reduced downy mildew susceptibility

Gene co-expression network analysis provides a novel insight into the dynamic response of wheat to powdery mildew stress

Powdery mildew (Blumeria graminis f. sp. Tritici, (Bgt)) is an important worldwide fungal foliar disease of wheat (Triticum aestivum) responsible for severe yield losses. The development of resistance genes and dissection of the resistance mechanism will therefore be beneficial in wheat breeding. The Bgt resistance gene PmAS846 was transferred to the hexaploid wheat lines N9134 from Triticum dicoccoides, and it is still one of the most effective resistance genes. Here, by RNA sequencing, we identified three co-expressed gene modules using pairwise comparisons and weighted gene co-expression network analysis during wheat–Bgt interactions compared with mock-infected plants. Hub genes of stress-specific modules were significantly enriched in spliceosomes, phagosomes, the mRNA surveillance pathway, protein processing in the endoplasmic reticulum, and endocytosis. Induced module genes located on chromosome 5BL were selected to construct a protein–protein interaction network. Several proteins were predicted as the key hub node, including Hsp70, DEAD/DEAH box RNA helicase PRH75, elongation factor EF-2, cell division cycle 5, ARF guanine-nucleotide exchange factor GNOM-like, and protein phosphatase 2C 70 protein, which interacted with several disease resistance proteins such as RLP37, RPP13 and RPS2 analogues. Gene ontology enrichment results showed that wheat could activate binding functional genes via an mRNA transcription mechanism in response to Bgt stress. Of these node genes, GNOM-like, PP2C isoform X1 and transmembrane 9 superfamily member 9 were mapped onto the genetic fragment of PmAS846 with a distance of 4.8 Mb. This work provides the foundations for understanding the resistance mechanism and cloning the resistance gene PmAS846

The Effectiveness of Trichoderma spp. against Downy Mildew Disease of Corn

Introduction: One of environmentally friendly method for controlling plant diseases is the use of Trichoderma spp. as a natural controlling agent. Objectives: The objective of this research was to find out the effectiveness of Trichoderma spp. against downy mildew disease. Methodology: This research was conducted in the Plant Pest and Disease Laboratory in the Plant Protection Department of Faculty of Agriculture in Lampung University. This research used completely randomized design consisting without treatment (0), Trichoderma spp. Gading Rejo Region (GDR) isolate (1) Trichoderma spp. Nusantara Tropical Farm (NTF) isolate (2), and Trichoderma spp. Trimurjo (TRJ) isolate (3) treatments which were applied to the plant growing points as fungicide (B) and as inducer of plant resistance to be applied in the plant roots (P). Results: The research results showed that the Trichoderma spp. treatments could reduce the disease occurrence at 4 and 5 days after inoculation, but they could not reduce the disease severity and improve stover dry weight of corn plant. Conclusion: The Trichoderma spp. Treatment as biofungicide and plant resistance inducer are effective against the incubation period and suppress the disease occurrence of downy mildew disease significantly at the early course of the disease.

Bremia itoana (Oomycota, Peronosporales), a Specialized Downy Mildew Pathogen on an East Asian Plant, Crepidiastrum sonchifolium (Asteraceae)

Crepidiastrum sonchifolium, a flowering plant in the daisy family (Asteraceae), is native to East Asia. In Korea, this plant is a locally cultivated vegetable, and its market size is gradually growing. Since the plants with downy mildew infection were initially found at a private farm of Chuncheon city, the occurrences have continued in commercial farms of other regions, highlighting that this disease is spreading throughout Korea. The pathogen was attributed to a member of the genus Bremia that contains many specialized species, each of which displays a narrow host spectrum on Asteraceae. Based on morphological and molecular phylogenetic analyses, along with the high host specificity recently proven for Bremia species, the identity of the causal agent was confirmed as a so far undescribed species of Bremia. Here, we introduce Bremia itoana sp. nov., specific to C. sonchifolium.

Cloning and analysis of a powdery mildew responsive gene CmSAMDC from Cucumis melo L / 生物工程学报

In order to investigate the effect of S-adenosylmethionine decarboxylase (SAMDC) gene in melon resistance to powdery mildew, according to the previous results of EST sequences from cDNA-AFLP library and the melon genome sequence data, the SAMDC gene was isolated from Chinese wild melon clone 'Yuntian930' by RT-PCR and designated as CmSAMDC (GenBank Accession No. KF151861). The mORF (main open reading frame) was 1 095 bp encoding 364 amino acids with a molecular mass of 40 kDa. The predicted protein sequence showed high similarity with Cucumis sativus and Citrofortunella microcarpa. The SDS-PAGE showed that the expression protein was a fusion protein with the molecular weight of 40 kDa, which perfectly matched the mass calculated from the amino acid sequence. Quantitative real-time PCR analysis indicated that the expression level of CmSAMDC reached a maximum at 48 hpi (hours post inoculation) that over 7-fold to 0 hpi, and the expression of CmSAMDC was also detected in tendril, root, leaf and stem. These results indicate that CmSAMDC gene may play protective roles in melon resistance to powdery mildew infection.

Chemical control of foliar diseases in soybean depends on cultivar and sowing date / O controle químico de doenças foliares na cultura da soja depende do cultivar e da época de plantio

The aim was to study the effect of early application of two fungicide mixtures on the control of Asian rust and powdery mildew, as well as on grain yield in five soybean cultivars at two sowing dates. The experiment was carried in the experimental area of FAMV/UPF. The cultivars A 4910 RG (super-early), BMX Apolo RR, A 6001 RR and Fundacep 55 RR (early) and Coodetec 214 RR (moderate), established at 13/11/2007 and 3/12/2007 were used. Trifolia of these cultivars were treated twice with the fungicides ciproconazol + azoxystrobin (Priori Xtra®, 0.3 L ha-1 plus Nimbus® adjuvant 0.6 L ha- 1) and epoxiconazol + pyraclostrobin (Opera®, 0.5 L ha-1), in three moments 1: pre-closure of the space between the lines and 21 days after; 2: pre-closure of space between rows and R5.1 stage (10% of beginning seed); and 3: R1 (beginning bloom) and R5.1 stages. The severity (% of affected leaf area) of powdery mildew and number of lesions cm2 of Asian rust were evaluated. After that plants were harvested, the thousand grain weight (g) and grain yield (kg ha-1) were quantified. The experimental design was a split-plot with four replicates, where the main plot were the five cultivars, and the subplots were the control treatment (untreated plants) and the six chemical control programs. Tukey and t-Student tests (p0.05) were used for separation of means of treatments and seasons, respectively. In general terms, foliar application of fungicides controlled both Asian rust and powdery mildew, as well as generated an increase on the thousand grain weight and grain yield. However, there seems to be an interaction among soybean genotypes and sowing date. Thus, our results allow us to infer that the chemical control of leaf diseases in the soybean crop depends of the cultivar and sowing date.

O objetivo foi estudar o efeito da aplicação antecipada de duas misturas de fungicidas no controle da ferrugem asiática e do oídio, bem como no rendimento de grãos em cinco cultivares de soja em duas épocas de semeadura. O experimento foi conduzido no campo experimental da FAMV/UPF. Utilizaram-se as cultivares A 4910 RG (super precoce), BMX Apolo RR, A 6001 RR e Fundacep 55 RR (precoces) e Coodetec 214 RR (moderado), estabelecidas em 13/11/2007 e 3/12/2007. Os fungicidas piraclostrobina + epoxiconazole e azoxistrobina + ciproconzole foram pulverizados duas vezes em 1: pré-fechamento do espaço entre as linhas e 21 dias após, 2: pré-fechamento do espaço entre as linhas e R5.1 (10% de granação), e 3: R1 (início da floração) e R5.1. Avaliaram-se a severidade (% da área foliar afetada) do oídio e o número de lesões cm2 da ferrugem asiática. Logo após as plantas foram colhidas, o peso de mil grãos (g) e rendimento de grãos (kg ha-1) foram quantificados. O delineamento experimental utilizado foi o de parcelas divididas com quatro repetições, onde a parcela principal foram as cinco cultivares, e as subparcelas foram o tratamento controle (plantas não tratadas) e os seis programas de controle químico. Para a separação das médias dos tratamentos e épocas, foram utilizados os testes de Tukey e t-Student (p0.05), respectivamente. De modo geral, a aplicação foliar de fungicidas controlou tanto a ferrugem asiática como o oídio, assim como também gerou um aumento do peso de mil grãos e rendimento de grãos. No entanto, parece existir uma interação entre os genótipos e data de semeadura. Assim, nossos resultados nos permitem inferir que o controle químico das doenças foliares na cultura da soja depende do cultivar e da data de semeadura.

Composition Changes of Aurantii Fructus before and after Fermentation Processing and Its Technology Op-timization / 中国药房

OBJECTIVE:To compare the composition changes of Aurantii fructus before and after fermentation processing and optimize its fermentation processing technology. METHODS:UPLC was conducted to compare the raw and fermentation processed products of same batch of Aurantii fructus,and ensure the chromatographic peaks after fermentation processing. Using peak areas of 4 chromatographic peaks and mildew characteristics of samples as index,fermentation temperature,humidity and time as factor, L9(34)orthogonal test was designed to optimize the fermentation processing technology,and verified it. RESULTS:After fermenta-tion processing,Aurantii fructus obviously showed 2 new monosaccharide glycosides components;the optimized fermentation tech-nology was as follows as fermentation temperature of 30 ℃,humidity of 70% and time of 7 d;verification test results showed RSD of each indicator of decoction pieces prepared by optimized fermentation technology in 3 tests were lower than 2.0%(n=3). CONCLUSIONS:Fermentation processing may lead obvious chemical composition changes in Aurantii fructus;the optimized fer-mentation processing technology can increase the contents of characteristic peaks.

Diversity, Phylogeny, and Host-Specialization of Hyaloperonospora Species in Korea

The genus Hyaloperonospora (Peronosporaceae; Oomycota) is an obligate biotrophic group that causes downy mildew disease on the Brassicaceae and allied families of Brassicales, including many economically relevant crops, such as broccoli, cabbage, radish, rape, and wasabi. To investigate the diversity of Hyaloperonospora species in northeast Asia, we performed a morphological analysis for the dried herbarium specimens collected in Korea, along with molecular phylogenetic inferences based on internal transcribed spacer rDNA and cox2 mtDNA sequences. It was confirmed that 14 species of Hyaloperonospora exist in Korea. Of these, three species, previously classified under the genus Peronospora, were combined to Hyaloperonospora: H. arabidis-glabrae comb. nov. (ex Arabis glabra), H. nasturtii-montani comb. nov. (ex Rorippa indica), and H. nasturtii-palustris comb. nov. (ex Rorippa palustris). In addition, finding two potentially new species specific to northeast Asian plants is noteworthy in support of the view that the species abundance of Hyaloperonospora has been underestimated hitherto.

Induction of Defense-Related Physiological and Antioxidant Enzyme Response against Powdery Mildew Disease in Okra (Abelmoschus esculentus L.) Plant by Using Chitosan and Potassium Salts

Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) (C₆H₇kO₂), and potassium bicarbonates (PB) (KHCO₃), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.

Research progresses and formulation development of natural anti-mildew agents based on Chinese herbal medicines / 中国中药杂志

Owing to the intrinsic factors and some extrinsic environmental conditions, many foods, agricultural products and Chinese materia medicas (CMMs), if not handled properly in the processes of growth, harvesting, processing and storage, can be easily contaminated by all kinds of molds to produce mycotoxins of serious toxicity, which will not only affect the quality, safety and effectiveness of CMMs, but also result in potential threatens to human and animal's health and life. Therefore, in recent decades, it has become the focus on how to prevent and control the foods, agricultural products and CMMs from being moldy and producing toxicity for scientific preservation. Many Chinese herbal medicines (CHMs) especially those with high content of volatile oils with strong antifungal activities have been applied for the scientific preservation of foods, agricultural products and CMMs. Based on these situations, natural anti-mildew agents have been further developed and made into some useful dosage forms, such as tablets, aerosol, liposomes and inclusion, which will not only greatly expand the application scope of CHMs to make the use of anti-mildew agents more convenient, but also achieve the sustained or controlled release of the antifungal effect for scientific preservation of foods, agricultural products and CMMs.

Genome-wide Identification, Classification and Expression Analysis of the Mildew Resistance Locus O ( MLO ) Gene Family in Sweet Orange ( Citrus sinensis )

ABSTRACT Mildew resistance Locus O (MLO), a gene family specific to plants, plays significant roles in the resistance to powdery mildew (PM) and response to a variety of abiotic stresses, plant growth and development. Despite their importance as barley, rice, wheat, few studies are reported in dicots except Arabidopsis; no global analysis has been performed in the burgeoning model fruit plant sweet orange (Citrus sinensis). The recent release of the genome sequences of C. sinensis provides an opportunity to conduct a comprehensive overview the evolution and features of the MLO gene family in sweet orange. In this study, amount to 14 members of the Citrus sinensis MLO gene (CisMLO) family according to their gene structures, conserved motifs, and similitude among their presumptive Arabidopsis and rice orthologs were identified in silico. Based on these analyses, all CisMLOs were grouped into six clades and expanded partly due to one tandem duplication and two segmental duplication events. Survey of their chromosomal distributions uncovered that 14 CisMLOs are localized across 6 chromosomes. Multiple-sequence alignments showed that 11 of them shared seven highly conserved transmembrane domains (TMs), while all of the sweet orange MLO proteins except CisMLO4/14 had a calmodulin-binding domain for MLO function. Expression analysis demonstrated that the MLO gene family has a diverse tissue-specific expression profiles in the sweet orange development and plays potential critical roles in stress responses. These findings will facilitate further studies of evolutionary pattern and biological functions of MLO genes in sweet orange.

rDNA-ITS and 28 S rDNA D1/D2 sequence analysis of downy mildew pathogen from Aconitum carmichaeli / 中草药

Objective: To define sequences about rDNA-ITS and 28 S rDNA D1/D2 of Peronospora aconiti separated from cultivated Aconitum carmichaeli in Jiangyou area of Sichuan province and provide a theoretical basis for the diagnosis and prevention of downy mildew disease. Methods: Spores and hyphae of P. aconiti from diseased plants were collected and total genomic DNA of pathogen were extracted and then rDNA-ITS and 28 S rDNA D1/D2 fragment were amplified and sequenced. According to the above results, the abutment (Neighbor-joining, NJ) phylogenetic tree of pathogen was constructed and analyzed. Results: The rDNA-ITS and 28 S rDNA D1/D2 sequences of P. aconiti were sequenced and compared according to the database from NCBI. Compared that with P. pulveracea and P. aparines, the similarity of rDNA-ITS sequences of P. aconiti was 94%. The similarity of 28 S rDNA D1/D2 sequences of P. aconiti was 97% compared that with P. pulveracea, P. ficariae and P. bulbocapni. Conclusion: The results of morphological identification of downy mildew pathogen separated from A. carmichaeli are consistent with those from molecular identification (rDNA-ITS and 28 S rDNA D1/D2 sequences) and the pathogen of Aconitum downy mildew should be P. aconiti. Therefore, rDNA-ITS and 28 S rDNA D1/D2 sequences constructed in this paper can be used to identify downy mildew pathogen from Aconitum carmichaeli Debx.