Allium Spp Research Articles

Pathogenicity Differentiation of Fusarium spp. Causing Fusarium Basal Rot and Wilt Disease in Allium spp.

Here, 12 Fusarium strains, previously described as F. oxysporum f. sp. cepae (Foc), were examined via multi-locus sequencing of calmodulin (cmdA), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1), to verify the taxonomic position of Foc in the newly established epitype of F. oxysporum. The strains in this study were divided into two clades: F. nirenbergiae and Fusarium sp. To further determine the host specifications of the strains, inoculation tests were performed on onion bulbs and Welsh onion seedlings as potential hosts. Four strains (AC145, AP117, Ru-13, and TA) isolated from diseased onions commonly possessed the secreted in xylem (SIX)-3, 5, 7, 9, 10, 12, and 14 genes and were pathogenic and highly aggressive to onion bulbs, whereas all strains except for one strain (AF97) caused significant inhibition of Welsh onion growth. The inoculation test also revealed that the strains harboring the SIX9 gene were highly aggressive to both onion and Welsh onion and the gene was expressed during infection of both onions and Welsh onions, suggesting the important role of the SIX9 gene in pathogenicity. This study provides insights into the evolutionary pathogenicity differentiation of Fusarium strains causing Fusarium basal rot and wilt diseases in Allium species.

Antimicrobial Efficacy of Phyto-L, Thiosulfonate from Allium spp. Containing Supplement, against Escherichia Coli Strains from Rabbits.

Colibacillosis, caused by enteropathogenic Escherichia coli (EPEC), is one of the most common diseases in rabbit farms, resulting in economic losses due to mortality and decrease in production. Until recently, antimicrobials were used to both treat and prevent disease on livestock farms, leading to the possible risk of antimicrobial resistance (AMR) and the selection of multidrug-resistant (MDR) bacteria. Therefore, interest in alternative control methods, such as the use of natural substances, has increased in the scientific community. The aim of this study was to evaluate the antimicrobial efficacy of Phyto-L (Pro Tech s.r.l.), a product containing organosulfur compounds (OSCs) such as propyl propane thiosulfonate (PTSO) from Allium spp., against 108 strains of E. coli isolated from rabbits with colibacillosis from 19 farms. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Phyto-L were assessed. Bacterial suspensions with a charge of 108 CFU/mL, corresponding to those found in the rabbit gut under pathologic conditions, were tested with different concentrations from 20 to 0.15 μL/mL of Phyto-L. For each strain, the MIC and concentrations above the MIC were plated on Tryptic Soy agar (TSA) without Phyto-L to assess the MBCs. MIC and MBC values ranged from 1.25 to 5 μL/mL and 1.25 to 20 μL/mL, respectively, depending on the strain tested. The data showed an interesting antibacterial activity of Phyto-L against EPEC strains. Therefore, this product could be effective in preventing colibacillosis in field application, especially considering that 104-105 CFU/g of feces is the amount of E. coli usually found in the gut contents of rabbits under physiological condition.

Beneficial Effects of Daily Consumption of Garlic and Onion Extract Concentrate on Infectious Respiratory Diseases in Elderly Resident Volunteers.

Aging is a biological process with high susceptibility to several infections. This risk increases in older patients in residential care facilities (RCF). Thus, there is a clear demand for developing preventive interventions with new therapeutic compounds that combine efficacy and safety. This could be the case of compounds derived from plants of the genus Allium spp. The purpose of this study was to evaluate the impact of a combination of a garlic and onion extract concentrate standardized in organosulfur compounds derived from propiin on the incidence of respiratory tract infections in elderly patients of RCF. Sixty-five volunteers were selected at random to receive a placebo or a single daily dose of the extract for thirty-six weeks. Different clinical visits were performed to evaluate the main respiratory diseases with an infectious origin, as well as the associated symptoms and their duration. The extract showed a clinical safety profile and significantly reduced the incidence of respiratory infections. Moreover, the treatment decreased the number and duration of the associated symptoms compared with the placebo group. For the first time, we demonstrated the protective effect of Alliaceae extract in respiratory infectious diseases in elderly healthy volunteers, which could be used prophylactically against the most common infectious respiratory diseases.

Analytical Platform for the Study of Metabolic Pathway of Propyl Propane Thiosulfonate (PTSO) from Allium spp.

The present work is focused on the development of an analytical platform to elucidate the metabolic pathway of PTSO from onion, an organosulfur compound well-known for its functional and technological properties and its potential application in animal and human nutrition. This analytical platform consisted of the use of gas chromatography-mass spectrometry (GC-MS) and ultra-high performance liquid chromatography quadrupole with time-of-flight MS (UHPLC-Q-TOF-MS) in order to monitor volatile and non-volatile compounds derived from the PTSO. For the extraction of the compounds of interest, two different sample treatments were developed: liquid-liquid extraction (LLE) and salting-out assisted liquid-liquid extraction (SALLE) for GC-MS and UHPLC-Q-TOF-MS analysis, respectively. Once the analytical platform was optimised and validated, an in vivo study was planned to elucidate PTSO metabolisation, revealing the presence of dipropyl disulfide (DPDS) in liver samples with concentrations between 0.11 and 0.61 µg g-1. The DPDS maximum concentration in the liver was observed at 0.5 h after the intake. DPDS was also present in all plasma samples with concentrations between 2.1 and 2.4 µg mL-1. In regard to PTSO, it was only found in plasma at times above 5 h (0.18 µg mL-1). Both PTSO and DPDS were excreted via urine 24 h after ingestion.

Genome-wide association and dissociation studies in Pantoea ananatis reveal potential virulence factors affecting Allium porrum and Allium fistulosum × Allium cepa hybrid.

Pantoea ananatis is a member of a Pantoea species complex that causes center rot of bulb onions (A. cepa) and also infects other Allium crops like leeks (Allium porrum), chives (Allium schoenoprasum), bunching onion or Welsh onion (Allium fistulosum), and garlic (Allium sativum). This pathogen relies on a chromosomal phosphonate biosynthetic gene cluster (HiVir) and a plasmid-borne thiosulfinate tolerance cluster (alt) for onion pathogenicity and virulence, respectively. However, pathogenicity and virulence factors associated with other Allium species remain unknown. We used phenotype-dependent genome-wide association (GWAS) and phenotype-independent gene-pair coincidence (GPC) analyses on a panel of diverse 92 P. ananatis strains, which were inoculated on A. porrum and A. fistulosum × A. cepa under greenhouse conditions. Phenotypic assays showed that, in general, these strains were more aggressive on A. fistulosum × A. cepa as opposed to A. porrum. Of the 92 strains, only six showed highly aggressive foliar lesions on A. porrum compared to A. fistulosum × A. cepa. Conversely, nine strains showed highly aggressive foliar lesions on A. fistulosum × A. cepa compared to A. porrum. These results indicate that there are underlying genetic components in P. ananatis that may drive pathogenicity in these two Allium spp. Based on GWAS for foliar pathogenicity, 835 genes were associated with P. ananatis' pathogenicity on A. fistulosum × A. cepa whereas 243 genes were associated with bacterial pathogenicity on A. porrum. The Hivir as well as the alt gene clusters were identified among these genes. Besides the 'HiVir' and the alt gene clusters that are known to contribute to pathogenicity and virulence from previous studies, genes annotated with functions related to stress responses, a potential toxin-antitoxin system, flagellar-motility, quorum sensing, and a previously described phosphonoglycan biosynthesis (pgb) cluster were identified. The GPC analysis resulted in the identification of 165 individual genes sorted into 39 significant gene-pair association components and 255 genes sorted into 50 significant gene-pair dissociation components. Within the coincident gene clusters, several genes that occurred on the GWAS outputs were associated with each other but dissociated with genes that did not appear in their respective GWAS output. To focus on candidate genes that could explain the difference in virulence between hosts, a comparative genomics analysis was performed on five P. ananatis strains that were differentially pathogenic on A. porrum or A. fistulosum × A. cepa. Here, we found a putative type III secretion system, and several other genes that occurred on both GWAS outputs of both Allium hosts. Further, we also demonstrated utilizing mutational analysis that the pepM gene in the HiVir cluster is important than the pepM gene in the pgb cluster for P. ananatis pathogenicity in A. fistulosum × A. cepa and A. porrum. Overall, our results support that P. ananatis may utilize a common set of genes or gene clusters to induce symptoms on A. fistulosum × A. cepa foliar tissue as well as A. cepa but implicates additional genes for infection on A. porrum.

Expression Profiling and Functional Analysis of Candidate Odorant Receptors in Galeruca daurica.

Simple SummaryOdorant receptors (ORs) play an important role in the olfactory system in insects. However, there is no functional research on the odorant receptors of Galeruca daurica. In this study, 21 OR genes were identified from the transcriptome database of G. daurica adults. Most GdauORs were mainly expressed in antennae, and the expression levels of GdauORs in adults were affected by age. When GdauOR4, GdauOR15, and GdauORco were silenced by RNAi, the electrophysiological responses to host plant volatiles were significantly decreased.Galeruca daurica (Joannis) is an oligophagous pest in the grasslands of Inner Mongolia, China, which feed mainly on Allium spp. Odorant receptors (ORs) play an important role in the olfactory system in insects, and function together with olfactory co-receptor (ORco). In this study, 21 OR genes were identified from the transcriptome database of G. daurica adults, and named GdauOR1-20 and GdauORco. The expression profiles were examined by RT-qPCR and RNA interference (RNAi) and electroantennogram (EAG) experiments were conducted to further identify the olfactory functions of GdauOR4, GdauOR11, GdauOR15, and GdauORco. It was found that 15 GdauORs (OR1, OR3-6, OR8, OR11-13, OR15, OR17-20, and ORco) were mainly expressed in antennae, and the expression levels of GdauORs in adults were affected by age. When GdauOR4, GdauOR15, and GdauORco were silenced by RNAi, the electrophysiological responses to host plant volatiles were significantly decreased in G. daurica. This study lays a necessary foundation for clarifying the mechanism on finding host plants in G. daurica.

Effect of some two tree extractives on Sclerotium cepivorum causing white rot in Allium spp.

The present study was undertaken to investigate the effect of using different extracts of two types of trees (Jatropha curcas seeds and Taxodium distichium cones). The solvents used were distilled water and ethanol. Determination of bioactive components of each extract was carried out using gas chromatography/ Mass Spectrometry (GC/MS) analysis. In general, ethanolic extract was the most effective on the both of linear growth, sclerotial numbers and mycelium characteristics of Sclerotium cepivorum than both of the cold or hot water extracts compared to control. Under In vitro conditions, treated with 20% of ethanol solvent showed a fungicidal effect meanwhile, fungistatic effects appeared at 5% for reduction of the mycelium growth..In the greenhouse experiments, the results indicated that onion transplants treated with ethanolic extract of taxodium and jatropha at 20% resulted in significant reduction to the disease with a significant increase in bulb yield compared with a check treatments. This report is one of few papers which using taxodium cones and jatropha seeds as antifungal substances against plant pathogens especially S. cepivorum under worldwide and Egypt conditions.

Viruses Without Borders: Global Analysis of the Population Structure, Haplotype Distribution, and Evolutionary Pattern of Iris Yellow Spot Orthotospovirus (Family Tospoviridae, Genus Orthotospovirus).

Iris yellow spot, caused by Iris yellow spot orthotospovirus (IYSV) (Genus: Orthotospovirus, Family: Tospoviridae), is an important disease of Allium spp. The complete N gene sequences of 142 IYSV isolates of curated sequence data from GenBank were used to determine the genetic diversity and evolutionary pattern. In silico restriction fragment length polymorphism (RFLP) analysis, codon-based maximum likelihood studies, genetic differentiation and gene flow within the populations of IYSV genotypes were investigated. Bayesian phylogenetic analysis was carried out to estimate the evolutionary rate. In silico RFLP analysis of N gene sequences categorized IYSV isolates into two major genotypes viz., IYSV Netherlands (IYSVNL; 55.63%), IYSV Brazil (IYSVBR; 38.73%) and the rest fell in neither group [IYSV other (IYSVother; 5.63%)]. Phylogenetic tree largely corroborated the results of RFLP analysis and the IYSV genotypes clustered into IYSVNL and IYSVBR genotypes. Genetic diversity test revealed IYSVother to be more diverse than IYSVNL and IYSVBR. IYSVNL and IYSVBR genotypes are under purifying selection and population expansion, whereas IYSVother showed decreasing population size and hence appear to be under balancing selection. IYSVBR is least differentiated from IYSVother compared to IYSVNL genotype based on nucleotide diversity. Three putative recombinant events were found in the N gene of IYSV isolates based on RDP analysis, however, RAT substantiated two among them. The marginal likelihood mean substitution rate was 5.08 × 10–5 subs/site/year and 95% highest posterior density (HPD) substitution rate between 5.11 × 10–5 and 5.06 × 10–5. Findings suggest that IYSV continues to evolve using population expansion strategies. The substitution rates identified are similar to other plant RNA viruses.

Characterization of two Cucumber mosaic virus isolates infecting Allium cepa in Turkey

Cucumber mosaic virus (CMV) is polyphagous, infecting plants in several families. CMV has occurred as a minor pathogen in Allium crops in several Mediterranean countries, but little was known of the virus naturally infecting Allium spp. This study completed molecular and biological characterization of CMV-14.3Po and CMV-15.5Po, two newly identified CMV isolates infecting onion (Allium cepa L.) in Turkey. Phylogenetic, and nucleotide and amino acid sequence identity analyses of partial RNA2 and RNA3 of the two isolates showed that they were very similar to other CMV isolates from Mediterranean, European, and East Asian countries. Phylogenetic analysis of the partial sequence of RNA3 also showed that the onion isolates belong to subgroup IA. Onion isolates were mechanically transmissible, and caused mild leaf malformation on onion, severe leaf malformation and stunting on garlic (Allium sativus L.), and mosaic and mottle on cucumber (Cucumis sativus L.) and melon (Cucumis melo L.).

Effects of temperature on the immature development, longevity, feeding and fecundity of Liriomyza chinensis (Diptera: Agromyzidae) on green bunching onion (Allium fistulosum)

The stone leek leafminer, Liriomyza chinensis (Kato), has become a serious pest on Allium spp. However, knowledge concerning the biology of L. chinensis, which affect development of control programs, is still limited. Therefore, this experiment was conducted during 2020 at Entomology Laboratory, Faculty of Agronomy, University of Agriculture and Forestry, Hue University, Vietnam to study the effects of temperature on development, longevity, feeding and fecundity of L. chinensis under laboratory conditions. Liriomyza chinensis used for the present study were collected from green bunching onion fields at Hue City, Central Vietnam and reared on green bunching onion, Allium fistulosum L. in an environmental chamber at a constant temperature of 25 ± 0.5, 27.5 ± 0.5 and 30 ± 0.5°C, 70±10% RH and a 16L: 8D photoperiod. Developmental time, longevity, feeding and fecundity were inversely proportional to temperature. Total developmental times from egg to adult emergence decreased from 20.9 to 13.4 days for temperatures from 25 to 30°C. The longevities of L. chinensis were 9.2, 10.8 and 12.0 days at 25, 27.5 and 30°C, respectively. Females made the average of 1004.2, 1716.8 and 2549.0 punctures during her lifespan at 25, 27.5 and 30°C, respectively. The females laid means of 54.2, 115.2 and 134.8 eggs at 25, 27.5 and 30°C, respectively. These data are useful for predicting population dynamics of L. chinensis under field conditions and determining the maximum proportion of susceptible individuals for facilitating improved timing of application of control measures.

Simplified rapid differentiation of Liriomyza chinensis Kato (Diptera; Agromyzidae) genotypes A and B using PCR‐RFLP

AbstractThe stone leek leafminer Liriomyza chinensis Kato is one of the most important pests of Allium spp. In recent years, a new genotype of L. chinensis, genotype B, has been shown to cause more severe damage to Allium spp. compared with the native genotype A in Japan. Thus, identification of the genotypes is important for establishing L. chinensis control strategies. In this study, we developed a simple and rapid method of genotype identification using PCR‐restriction fragment length polymorphism (RFLP). Primers were designed to mitochondria cytochrome oxidase subunit I gene (mtCOI) nucleotide sequences from both genotypes. Genotypes A and B were successfully identified using the restriction enzymes PvuI and DdeI, respectively. Using PCR‐RFLP, we identified the genotype of L. chinensis samples (n = 108) collected in seven Japanese bunching onion fields in Ibaraki Prefecture, Japan. All individuals were shown to be genotype B, as expected.

Antiviral Activity, Phytochemistry and Toxicology of Some Medically Interesting Allium Species: A Mini Review

Aims: COVID-19 pandemic affects hundreds of thousands of people worldwide. Since there is no effective treatment, the need of finding alternative methods, which can help to curb this pandemic is urgent. This study aims to collect the information on the virucidal and toxicity properties of the Allium species. This genus is known to be source of nutraceuticals and also used as food. In this context, species of this genus can be proposed as an alternative solution against COVID-19.
 Methodology: The literature review was conducted on Allium spp during searches on different databases such as PubMed, PubMed Central, Science Direct, Scielo, DOAJ, Science alert and Google scholar. The scientific names of Allium species, antiviral compounds, antiviral activity and toxicology of the plants of interest were used as keywords. Mendeley was used to make bibliographic references and the chemical structures of the natural compounds from Allium genus were drawn using ChemBioDraw Ultra 12.0 software.
 Results: The findings from literature review showed that the Allium genus has demonstrated antiviral activity on several types of virus (Herpes simplex virus type 1, Herpes simplex virus type 2, Human immunodeficiency virus, Influenza virus, Cytomegalovirus, Human papillomavirus, Vesicular stomatitis virus, vaccinia virus, and human rhinovirus type 2 human cytomegalovirus). The species of this genus have also been used as food. Some species of Allium genus contain minerals such as Zinc, which have shown an effect on SARS-CoV-1, and could be involved in account for the reported antiviral effect.
 Conclusion: Edible Allium species could be used in the management of COVID-19. Molecular docking of main molecules of Allium species with SARS-CoV-2 protease is in progress.

Development of – 80 °C storage for Allium shoot tips using D cryo-plate method

D cryo-plate method was successfully adapted for storage at – 80 °C and – 196 °C of Allium shoot tips. The optimal D cryo-plate method using garlic shoot tips for the storage at – 80 °C and – 196 °C includes preculture of shoot tips for 2 days at 25 °C on solidified 1/2 MS medium containing 0.3 M sucrose, then placing them in wells on an aluminum cryo-plate, embedded in calcium alginate gel. Osmoprotection was performed by immersing the cryo-plates with shoot tips for 30 min at 25 °C in 2.0 M glycerol and 1.0 M sucrose. The optimal dehydration time of shoot tips was for 30 to 180 min at 25 °C. Cooling was performed by transferring the samples on the cryo-plate into 2 ml cryotubes, then cooling into a deep freezer at – 80 °C for 14 days or directly plunging into liquid nitrogen (− 196 °C) for 60 min. The regrowth rate of shoot tips stored both at – 80 °C and – 196 °C was almost 100%. This optimized procedure was applied to seven Allium spp. The average regrowth rates after cooling at – 80 °C and – 196 °C were 95.3 and 94.0%, respectively. Thus, the storage of shoot tips at – 80 °C using D cryo-plate method is considered to be efficiently applicable for practical genebank storage. D cryo-plate method was successfully adapted for storage at – 80 °C of Allium shoot tips. Grass transition temperature of shoot tips after air desiccation were − 39.4 °C.

IPBS-полиморфизм редких реликтовых и исчезающих видов Allium, произрастающих на территории Казахстанского Алтая

Abstract. The purpose of the study. The estimation of genetic polymorphism of Kazakhstan populations of rare relict and endemic Allium species. The novelty of the research is the use of the modern molecular genetic iPBS (Inter- Primer Binding Site Polymorphism) method of DNA amplification to assess the genetic diversity of different populations of Allium sp., collected in their natural habitats in the Kazakhstan Altai. Methods. Samples of medicinal relict and endangered species A. ledebourianum, A. altaicum, A. microdiction were collected in the places of their natural growth in the territory of the Kazakhstan Altai. DNA was isolated from 3–5 day sterile seedlings using lysis STAB buffer with RNaseA. PBS primers were used to assess the genetic diversity of different populations of Allium spp. The amplification results obtained using different PBS primers were evaluated in the GenAlex 6.5 macro program for Excel. Results. The polymorphism of 16 genotypes of the rare relict and endangered Allium sp. was analyzed using 7 PBS primers. Clearly distinguishable amplicons were obtained, the number of which varied depending on the primer used. The dendrogram, based on UPGMA analysis, grouped the studied genotypes into 2 main clusters, one of which included samples from the A. altaicum population, and the second cluster included samples from the A. ledebourianum population. A. microdiction represented by one sample did not enter any cluster, and formed a basal branch in the dendrogram. The results of the study have revealed a high degree of iPBS polymorphism and genetic diversity in rare relict and endangered Allium sp. Practical significance. The use of the molecular genetic iPBS method allows to identify a high level of polymorphism, which can serve as a basis for the identification of various genotypes of the Allium sp., which will significantly supplement traditional preservation methods of natural populations of this genus.

Determination of Organosulfides from Onion Oil.

Qualitative and semi-quantitative analysis of organosulfides extracted from oil obtained by steam distillation of yellow onions was performed by gas chromatography-mass spectrometry (GC-MS). The extraction efficiency of organosulfides from onion oil was evaluated across four solvents: dichloromethane; diethyl ether; n-pentane; and hexanes. Analysis of solvent extracted organosulfides by GC-MS provided qualitative results that support the use of dichloromethane over other solvents based on identification of 27 organosulfides from the dichloromethane extract as compared to 10 from diethyl ether; 19 from n-pentane; and 17 from hexanes. Semi-quantitative evaluation of organosulfides present in the dichloromethane extract was performed using diallyl disulfide as the internal reference standard. Three organosulfides were detected in the extract at ≥5 mg/kg; 18 organosulfides between 3–5 mg/kg; and six organosulfides at <3 mg/kg. The E/Z isomers of 1-propenyl propyl trisulfide were among the most prevalent components extracted from the onion oil across all solvents; and 3,6-diethyl-1,2,4,5-tetrathiane was among the most abundant organosulfides in all solvents except hexanes. The method described here for the extraction of organosulfides from steam distilled onion oil surveys common solvents to arrive at a qualitative and semi-quantitative method of analysis for agricultural products involving onions; onion oil; and secondary metabolites of Allium spp.

Sensitivity of serological and polymerase chain reaction methods for detection of viruses in Allium spp.

Infection of Onion yellow dwarf virus (OYDV), Shallot yellow stripe virus (SYSV), and Garlic common latent virus (GCLV) has been reported on Allium spp. in Indonesia. Serology methods using enzyme-linked immunosorbent assay (ELISA), and dot immunobinding assay (DIBA) is a common method to detect viruses, while polymerase chain reaction (PCR) is popular as a molecular method to detect plant viruses nowadays. This research was conducted to assess the sensitivity of 3 detection methods, i.e. ELISA, DIBA and PCR for detecting viruses in Allium spp. Sensitivity level of each method was evaluated by diluting plant extract and antibody for ELISA and DIBA, and cDNA template for PCR. Result of this research showed that DIBA was able to detect OYDV, GCLV, and SYSV with plant extract dilution in the range of 10−1 to 10−2, and antibody dilution from 1:300 to 1:1000. ELISA seems to be more sensitive than DIBA because it was able to detect the same virus with plant extract dilution in the range of 10−1, 10−3, and 10−5, and antibody dilution from 1:300 to 1:1000. RT-PCR method was the most sensitive method compared to ELISA and DIBA because it has the highest accuracy, specification and sensitivity level. Specific DNA fragment was amplified using universal primers for Potyvirus and Carlavirus up to 10−3 and 10−4 dilution factor of cDNA respectively. Moreover, amplification using specific primers of OYDV, SYSV, and GCLV is more sensitive than using universal primers, because up to 10−5 dilution factor of cDNA was able to amplify virus target.

An overview on: Management of major disease of Allium spp

An overview on: Management of major disease of Allium spp

Soil disinfestation with dimethyl disulfide (DMDS) to manage the bacterial wilt of tomato in the tropics

Bacterial wilt, caused by Ralstonia solanacearum, is a major disease that affects tomato crops worldwide. In Martinique, the situation has changed drastically since 1999 with the emergence of a new genotype of R. solanacearum, phylotype IIB/4NPB. This genotype wilts tomato cultivars previously considered as resistant and cannot be controlled by any conventional method. Promising results have been reported based on the use of biofumigants and suppressive crops, among which the aqueous extract of Allium fistulosum, belonging to the Alliaceae family, has been shown to have antibacterial properties against R. solanacearum. This extract controlled the bacterial wilt of tomato when used as a preplant soil treatment. Dimethyl disulfide (DMDS) is one of the main biofumigant molecules of Allium spp. The efficacy of soil fumigation with DMDS in the tomato R. solanacearum pathosystem was investigated in Martinique. First, DMDS was evaluated in vitro inhibition bioassays and then in vivo conditions. The suppressive effect of DMDS on R. solanacearum populations in the soil was studied in a growth chamber and the disease control was evaluated in greenhouse conditions with DMDS. In vitro, DMDS suppressed the growth of R. solanacearum. In the growth chamber, fumigation with DMDS significantly reduced R. solanacearum populations with a clear concentration effect. No pathogen was detected in the soil seven days after treatment with DMDS at 10-2 mol L-1 whereas DMDS at 10-3 mol L-1 reduced populations Crom 5.9.106 to 5.5 105 cfu g-1 of dry soil. DMDS fumigation also reduced the incidence of tomato bacterial wilt in the greenhouse. In the untreated control, the disease affected 57% of the tomato plants whereas, with DMDS, only 2% of the plants were affected. These results demonstrate for the first time that DMDS can be used as a soil fumigant in future integrated bacterial wilt-management strategies.

Development of intron length polymorphic (ILP) markers in onion (Allium cepa L.), and their cross-species transferability in garlic (A. sativum L.) and wild relatives

Onion (Allium cepa L.) is a popular spice and a plant of high medicinal value. Conventional breeding and genetic improvement efforts were largely limited due to self-incompatibility and heterozygosity. Recently, marker assisted breeding has significantly reduced time and labour in developing elite varieties. But very limited polymorphic and cross-transferable markers are available in onion. There is an urgent need to develop polymorphic markers in Allium to expedite and introgress desirable traits from wild relatives (which are rich bioresource of various biotic and abiotic resistance genes) to A. cepa. Considering limited availability of reliable molecular markers in Allium and wild relatives, in current study, 20,204 ESTs (3750 contigs and 8364 singletons), of A. cepa were successfully utilized for identification of over 2689 intron length polymorphic (ILP) markers. A set of 30 markers was tested for polymorphism in onion and cross-transferability in garlic and related wild species. Among these, eighteen markers amplified at least one of the accessions of A. cepa. Transferability of these ILP markers was ranged from 21.7 to 95.7% in Allium spp. Low level of polymorphism in A. cepa compared to wild Allium species is reported. Based on the Jaccard dissimilarity matrix, a neighbour-joining tree was constructed, which clustered all the 23 varieties/accessions under three groups. All the varieties of A. cepa were clearly clustered separately under group I. However, there was intermixing of varieties/accessions of A. sativum L. and wild relatives, which may possibly be due to less number of markers validated for cross-transferability. In future, larger set of markers will be used to resolve the genetic variations among wild varieties and A. sativum These 18 polymorphic ILP markers could be utilised for diversity characterization of Allium spp., varietal identification, mapping of genes and introgression of desirable traits from wild relatives.

HOST RANGE PANTOEA ANANATIS THE CAUSAL AGENT OF BACTERIAL LEAF BLIGHT ON ALLIUM SPP.

Bacterial leaf blight disease caused by Pantoea ananatis has been reported affects some species of Allium spp. Here, we determined the species of Allium spp. that are not the hosts of the P.ananatis through a host range test. The study designed as a completely randomized design with five replications. Pathogenic bacteria of P. ananatis inoculated to shallot, onion, spring onion, garlic, chives, leek, and cung spring onion in the greenhouse of the Faculty of Agriculture Tadulako University. The incubation period and symptoms of after inoculated by P. ananatis then observed. The results showed that four llium species (onion, onion, scallion, and garlic) were hosts of P. ananatis while the other three species (chives, leek, and cung spring onion) were not hosts of P. ananatis.