DAUCI

Qualitative plant resistance mechanisms and pathogen virulence have been extensively studied since the formulation of the gene-for-gene hypothesis. The mechanisms involved in the quantitative traits of aggressiveness and plant partial resistance are less well-known. Nevertheless, they are prevalent in most plant-necrotrophic pathogen interactions, including the Daucus carota - Alternaria dauci interaction. Phytotoxic metabolite production by the pathogen plays a key role in aggressiveness in these interactions...

Three bacterial strains, designated DS48-6-5T, DS48-6-7 and DS48-6-9, were isolated from a sediment sample taken from Daechung Reservoir (Republic of Korea) at a water depth of 48 m. Cells of the strains were Gram-stain-negative, aerobic, rod-shaped and motile with a single polar flagellum. Comparative 16S rRNA gene sequence studies showed that the three isolates had clear affiliation with Betaproteobacteria and the closest relatives were Rhizobacter bergeniae KCTC 32299T, Rhizobacter dauci DSM 11587T and Rhizobacter fulvus KCTC 12591T with 97...

Strain BD3526T , isolated from raw yak milk collected in Tibet, China, was studied to determine its taxonomic status. The strain was Gram-reaction positive, motile, catalase-positive, aerobic or facultatively anaerobic. The DNA G+C content of the strain was 47.5 mol% and its peptidoglycan contained meso -diaminopimelic acid. The predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C15 : 0 , anteiso-C17 : 0 and C16 : 0 . Based on 16S rRNA gene sequence analysis, similarities among strain BD3526T and its most closely related species, Paenibacillus shenyangensis A9T , ' Paenibacillus dauci ' H9, ' Paenibacillus wulumuqiensis ' Y24 and Paenibacillus hunanensis DSM 22170T were 99...

Paenibacillus dauci sp. nov., a new kind of endophytic actinobacteria, is separated from the inner tissues of carrot sample, which forms intimated associations with carrot acting as biological control agents. Here we report a 5.37-Mb assembly of its genome sequence and other useful information, including the coding sequences (CDSs) responsible for biological processes such as antibiotic metabolic process, antimicrobial metabolism, anaerobic regulation and the biosynthesis of vitamin B and polysaccharide. This novel strain can be a potential source of novel lead products for exploitation in the field of pharmaceutical, agriculture and industry...

Combining biparental and multiparental connected population analyses was useful for the identification of 11 QTLs in two new genetic backgrounds of carrot resistance to Alternaria dauci and for breeding recommendations. Leaf blight due to the fungus Alternaria dauci is the major carrot foliar disease worldwide. Some resistance QTLs have been previously identified in one population, but the evaluation of additional genetic backgrounds with higher level of resistance would give opportunities for breeders to combine them by pyramiding...

In this paper, thermal (8-13 µm) and hyperspectral imaging in visible and near infrared (VNIR) and short wavelength infrared (SWIR) ranges were used to elaborate a method of early detection of biotic stresses caused by fungal species belonging to the genus Alternaria that were host (Alternaria alternata, Alternaria brassicae, and Alternaria brassicicola) and non-host (Alternaria dauci) pathogens to oilseed rape (Brassica napus L.). The measurements of disease severity for chosen dates after inoculation were compared to temperature distributions on infected leaves and to averaged reflectance characteristics...

Two Gram-staining-positive, aerobic, motile, endospore-forming, rod-shaped bacteria, designated strains Y24(T) and H9(T) were isolated from cold spring and carrot (Daucus L.) samples, respectively, in Xinjiang Uyghur Autonomous Region, north-western China. The taxonomic positions of the two new isolates were determined by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences and DNA-DNA hybridizations showed that strains Y24(T) and H9(T) were two different novel species belonging to the genus Paenibacillus, with Paenibacillus hunanensis FeL05(T) as their closest relative...

A novel, moderately thermophilic, acidophilic, Gram-variable, rod-shaped, endospore-forming bacterium was isolated from a spoiled mixed vegetable and fruit juice product that had the off-flavour of guaiacol. The bacterium, strain 4F(T), grew aerobically at 20-50 °C (optimum 40 °C) and pH 3.0-6.0 (optimum pH 4.0) and produced acid from glycerol, d-galactose and d-glucose. It contained menaquinone-7 (MK-7) as the major isoprenoid quinone and the DNA G+C content was 49.6 mol%. The predominant cellular fatty acids of strain 4F(T) were ω-alicyclic (ω-cyclohexane fatty acids), which are characteristic of the genus Alicyclobacillus...

A yellowish-pigmented bacterium, designated strain PLGR-1(T), was isolated from the root of Bergenia scopulosa collected from Taibai Mountain in Shaanxi Province, north-west China, and was subjected to a taxonomic study by using a polyphasic approach. Cells of strain PLGR-1(T) were Gram-stain-negative, strictly aerobic, rod-shaped, non-spore-forming and motile with a single polar flagellum. Growth occurred at 7-33 °C (optimum, 25-28 °C), at pH 5.0-10.0 (optimum, pH 6.0-7.0) and with 0-0.5 % (w/v) NaCl (optimum, 0 %)...

Although different mechanisms have been proposed in the recent years, plant pathogen partial resistance is still poorly understood. Components of the chemical warfare, including the production of plant defense compounds and plant resistance to pathogen-produced toxins, are likely to play a role. Toxins are indeed recognized as important determinants of pathogenicity in necrotrophic fungi. Partial resistance based on quantitative resistance loci and linked to a pathogen-produced toxin has never been fully described...

Despite its association with important agricultural crops, Phytophthora clade 8b is a poorly studied group of species. The clade currently consists of three officially described species (Phytophthora porri, P. brassicae and P. primulae) that are host-specific pathogens of leek, cabbages and Primula spp., respectively. However, over the past few decades, several other clade 8b-like Phytophthoras have been found on a variety of different host plants that were all grown at low temperatures in winter seasons. In this study, a collection of 30 of these isolates was subjected to a phylogenetic study using two loci (the rDNA ITS region and the mitochondrial cox1 gene)...

A rubber-degrading bacterium, the strain NS21, that was isolated from a soil sample in a botanical garden in Japan (Imai et al., 2011) was examined by phenotypic, phylogenetic and chemotaxonomic approaches to determine its taxonomic position. The strain NS21 was motile, possessing a single polar flagellum and a facultatively anaerobic straight rod. Analysis of the 16S rRNA and gyrB gene sequences of NS21 revealed a close relationship to the genus Rhizobacter. The predominant quinone type was Q-8. The G+C content of the NS21 genomic DNA was 70...

The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of morphologically similar taxa. This study aimed to assess if strains of four closely-related plant pathogens, i.e., accurately Alternaria dauci (ten strains), Alternaria porri (six), Alternaria solani (ten), and Alternaria tomatophila (ten) could be identified using multilocus phylogenetic analysis and Matrix-Assisted Laser Desorption Ionisation Time of Flight (MALDI-TOF) profiling of proteins...

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Eleven polymorphic microsatellite markers were isolated from the necrotrophic phytopathogenic fungus Alternaria dauci based on enriched genomic libraries. In order to assess allelic variability, the microsatellite loci were analysed in a collection of 43 isolates. The number of detected alleles in 11 loci ranged from two to 24 (mean 10.4). Test of cross-species amplification and sequencing of the resulting amplicons showed that some of these microsatellites could be used in different species such as Alternaria solani, Alternaria bataticola and Alternaria zinniae...

16S rRNA gene sequenced-based phylogeny indicates that Rhizobacter dauci ATCC 43778(T) branches within the radiation of Methylibium type strains. A comparative chemotaxonomic study including fatty acid methyl esters, polar lipids and polyamines reveals significant differences that, in combination with the topology of phylogenetic trees, support a dissection of the genus Methylibium. The proposals of this study include the transfer of Methylibium fulvum to the genus Rhizobacter as Rhizobacter fulvus comb. nov...

In most production areas, Alternaria leaf blight (ALB) is recognized as the most common and destructive foliage disease in carrot. To assess the genetic architecture of carrot ALB resistance, two parental coupling maps were developed with similar number of dominant markers (around 70), sizes (around 650 cM), densities (around 9.5 cM), and marker composition. The F(2:3) progenies were evaluated in field and tunnel for two scoring dates. The continuous distribution of the disease severity value indicated that ALB resistance is under polygenic control...

A leaf blight of carrot (Daucus carota) caused by Alternaria dauci was found in Alentejo (Ourique, Portugal). Morphological characteristics of the fungus are described.

ABSTRACT The efficacy of chemical (i.e., foliar fungicide sprays), genetic (i.e., moderately resistant cultivars), and cultural (i.e., drip-irrigation system) control measures was quantified individually and in combination in the management of Alternaria dauci, the causal agent of Alternaria leaf blight of carrot. Whereas host resistance and drip irrigation affected both the time of disease onset and the rate of disease progression, chemical control affected only the latter. In all cases, a single control measure did not provide an acceptable level of disease suppression...

ABSTRACT An ecological approach was used to select fungal antagonists effective against the seedborne pathogens Alternaria dauci and A. radicina on carrot. Twenty-five and 105 isolates originating from cereal and carrot habitats were screened against the pathogens in planta, respectively. Irrespective of isolate origin, fungal isolates belonging to Clonostachys rosea controlled pre- and postemergence death caused by A. dauci and A. radicina as effectively as the fungicide iprodione. Isolate IK726 of C. rosea was used in biopriming a seed lot with 29% A...