Cercospora beticola: The intoxicating lifestyle of the leaf spot pathogen of sugar beet.

Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen. TAXONOMY: Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora. HOST RANGE: Well-known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad-leaved dock) families. DISEASE SYMPTOMS: Leaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan-brown to reddish-purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore-bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses. MANAGEMENT: Application of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high-yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease. USEFUL WEBSITE: https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037.

Diversity of Bacterial Microbiota of Coastal Halophyte Limonium sinense and Amelioration of Salinity Stress Damage by Symbiotic Plant Growth-Promoting Actinobacterium Glutamicibacter halophytocola KLBMP 5180.

Plant-associated microorganisms are considered a key determinant of plant health and growth. However, little information is available regarding the composition and ecological function of the roots' and leaves' bacterial microbiota of halophytes. Here, using both culture-dependent and culture-independent techniques, we characterized the bacterial communities of the roots and leaves as well as the rhizosphere and bulk soils of the coastal halophyte Limonium sinense in Jiangsu Province, China. We identified 49 representative bacterial strains belonging to 17 genera across all samples, with Glutamicibacter as the most dominant genus. All Glutamicibacter isolates showed multiple potential plant growth promotion traits and tolerated a high concentration of NaCl and a wide pH range. Interestingly, further inoculation experiments showed that the Glutamicibacter halophytocola strain KLBMP 5180 isolated from root tissue significantly promoted host growth under NaCl stress. Indeed, KLBMP 5180 inoculation increased the concentrations of total chlorophyll, proline, antioxidative enzymes, flavonoids, K+, and Ca2+ in the leaves; the concentrations of malondialdehyde (MDA) and Na+ were reduced. A transcriptome analysis identified 1,359 and 328 differentially expressed genes (DEGs) in inoculated seedlings treated with 0 and 250 mM NaCl, respectively. We found that pathways related to phenylpropanoid and flavonoid biosynthesis and ion transport and metabolism might play more important roles in host salt stress tolerance induced by KLBMP 5180 inoculation compared to that in noninoculated leaves. Our results provide novel insights into the complex composition and function of the bacterial microbiota of the coastal halophyte L. sinense and suggest that halophytes might recruit specific bacteria to enhance their tolerance of harsh environments.IMPORTANCE Halophytes are important coastal plants often used for the remediation of saline coastal soils. Limonium sinense is well known for its medical properties and phytoremediation of saline soils. However, excessive exploitation and utilization have made the wild resource endangered. The use of endophytic and rhizosphere bacteria may be one of the suitable ways to solve the problem. This study was undertaken to develop approaches to improve the growth of L. sinense using endophytes. The application of actinobacterial endophytes ameliorated salt stress damage of the host via complex physiological and molecular mechanisms. The results also highlight the potential of using habitat-adapted, symbiotic, indigenous endophytic bacteria to enhance the growth and ameliorate abiotic stress damage of host plants growing in special habitats.

Limoniibacter endophyticus gen. nov., sp. nov., an alphaproteobacterium isolated from the roots of Limonium otolepis.

A Gram-negative bacterium, designated as strain YIM 690229T, was isolated from the roots of Limonium otolepis. The strain was able to grow at 10-40 °C (optimum, 28-37 °C), pH 6.0-8.0 (optimum, 7.0) and in the presence of up to 7% NaCl (w/v) (optimum, up to 2.5%). Comparative 16S rRNA gene sequence analysis revealed that strain YIM 690229T shared less than 93.9% sequence similarities with members within the order Rhizobiales, and was remotely related to members of the family Hyphomicrobiaceae. Strain YIM 690229T was characterized by the presence of Q-10 as the predominant respiratory lipoquinone. The major fatty acids (> 10%) detected were C18:1 ω7c, C16:0, anteiso-C15:0 and summed feature 4 (iso-C17:1 I and/or anteiso-C17:1 B). The polar lipids consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanoamine and two unidentified lipids. The genomic DNA G + C content was 57.2 mol%. Data from this polyphasic taxonomy study suggested that strain YIM 690229T should be classified as a new species of a new genus within the family Hyphomicrobiaceae for which the name Limoniibacter endophyticus gen. nov., sp. nov., is proposed. The type species of the genus Limoniibacter gen. nov. is Limoniibacter endophyticus. The type strain of the species Limoniibacter endophyticus sp. nov. is YIM 690229T (= KCTC 42097T = JCM 30141T = CCTCC AB 2014130T = CGMCC 1.12906T).

Glutamicibacter halophytocola sp. nov., an endophytic actinomycete isolated from the roots of a coastal halophyte, Limonium sinense.

A novel actinobacterium, designated KLBMP 5180T, was isolated from the surface-sterilized root of a coastal halophyte, Limonium sinense, collected from the city of Lianyungang, Jiangsu Province, eastern China. The isolate was Gram-stain-positive, aerobic and non-motile. The components of the cell-wall peptidoglycan were lysine, glutamic acid and alanine. The predominant menaquinone was MK-9. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, one unknown phospholipid, one unidentified glycolipid and two unidentified lipids. anteiso-C15 : 0 and iso-C16 : 0 were the major cellular fatty acids. The DNA G+C content of strain KLBMP 5180T was 60.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain KLBMP 5180T belongs to the genus Glutamicibacter and was related most closely to Glutamicibacter nicotianae DSM 20123T (99.3 % similarity), Glutamicibacterarilaitensis Re117T (99.3 %) and Glutamicibacter mysorens LMG 16219T (99.1 %); similarity to other type strains of the genus Glutamicibacter was lower than 98.5 %. However, DNA-DNA relatedness values between strain KLBMP 5180T, G . nicotianae DSM 20123T, G. arilaitensis Re117T and G. mysorens LMG 16219T were 47.5±2.6, 51.3±3.1 and 41.2±4.3 %, respectively. The combination of DNA-DNA hybridization, phylogenetic, phenotypic and chemotaxonomic data supported the suggestion that strain KLBMP 5180T represents a novel species of the genus Glutamicibacter, for which the name Glutamicibacterhalophytocola sp. nov. is proposed. The type strain is KLBMP 5180T (=DSM 101718T=KCTC 39692T).

Martelella suaedae sp. nov. and Martelella limonii sp. nov., isolated from the root of halophytes.

Two Gram-stain-negative, aerobic and endophytic bacterial strains, designated YC7033T and YC7034T, were isolated from the roots of halophytes (Suaeda maritime and Limonium tetragonum, respectively) inhabiting tidal flats of the Sacheon area, Korea. The phylogenetic analyses of 16S rRNA gene sequences showed that the two strains were closely related to Martelella endophytica YC6887T, Martelella mangrovi BM9-1T, Martelella radicis BM5-7T and Martelella mediterranea DSM 17316T at 97.6-99.1 % similarity. Sequence similarities with the type strains of another closely related genus, Rhizobium, were lower than 95.0 %. Both strains contained ubiquinone-10 (Q-10) as the major respiratory quinone system. The G+C contents of the genomic DNA of strains YC7033T and YC7034T were 52.8 and 62.2 mol%, respectively. The major fatty acids of both strain YC7033T and strain YC7034T were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C19 : 0 cyclo ω8c. On the basis of phylogenetic analysis, and biochemical and phenotypic characteristics, strains YC7033T and YC7034T represent two novel species of the genus Martelella, for which the names Martelella suaedae sp. nov. (type strain: YC7033T=KACC 17175T=NBRC 109440T) and Martelella limonii sp. nov. (type strain: YC7034T=KACC 17176T=NBRC 109441T) are proposed, respectively.

Herbihabitans rhizosphaerae gen. nov., sp. nov., a member of the family Pseudonocardiaceae isolated from rhizosphere soil of the herb Limonium sinense (Girard).

The taxonomic position of an actinobacterium, designated CPCC 204279T, which was isolated from a rhizosphere soil sample of the herb Limonium sinense collected from Xinjiang Province, China, was established using a polyphasic approach. Whole-cell hydrolysates of strain CPCC 204279T contained galactose and arabinose as diagnostic sugars and meso-diaminopimelic acid as the diamino acid. The muramic acid residues in the peptidoglycan were N-acetylated. The predominant menaquinone was MK-9(H4). The phospholipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The major fatty acids were iso-C16 : 0, iso-C16 : 0 2-OH, C16 : 1ω9c, iso-C16 : 1 and C16 : 0. The genomic DNA G+C content was 73.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CPCC 204279T should be placed in the family Pseudonocardiaceae, in which the strain formed a distinct lineage next to the genus Actinophytocola. Signature nucleotides in the 16S rRNA gene sequence showed that the strain contained the Pseudonocardiaceae family-specific 16S rRNA signature nucleotides and a genus-specific diagnostic nucleotide signature pattern. The combination of phylogenetic analysis and phenotypic characteristics supported the conclusion that strain CPCC 204279T represents a novel species of a new genus in the family Pseudonocardiaceae, for which the name Herbihabitans rhizosphaerae gen. nov., sp. nov. is proposed. Strain CPCC 204279T (=NBRC 111774T=DSM 101727T) is the type strain of the type species.

[Screening and biodiversity of endophytic and rhizosphere bacteria containing ACC deaminase from halophyte Limonium sinense (Girard) Kuntze].

Objective: We isolated and screened endophytic and rhizosphere bacteria with 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase from halophyte Limonium sinense (Girard) Kuntze collected from Jiangsu coastal area and investigated their diversity and plant growth promoting potential. Methods: Strains were obtained from inner tissues and rhizosphere soils using pure culture cultivation method and identified by 16S rRNA gene sequencing and phylogenetic analysis. Their potential plant growth promoting index of nitrogen fixation, phosphate solubilization, indoleacetic acid (IAA) production and NaCl tolerance ability were evaluated. Results: Eighteen strains with ACC deaminase were obtained and 13 of them exhibited more than 20 nmol α-KA/(mg Pr·h) ACC deaminase activity. Nine isolates produced IAA, 11 had nitrogen fixation ability and 7 of them had phosphate solubilization ability. Most of the isolates could grow under 0%-13% NaCl. The results of 16S rRNA sequencing showed that these strains belonged to seven genera, with Arthrobacter as the most predominant genus. Among them, strain KLBMP 5180 was found to be a potential novel species of the genus Arthrobacter. Conclusion: The halophyte plants Limonium sinense (Girard) Kuntze located in the area of coastal shoal contain a variety of symbiotic bacteria with ACC deaminase as well as the source of novel species. Some of them had good research prospect in the future.

Mycorrhizal limonium sinuatum (L.) mill. Enhances accumulation of lead and cadmium.

Heavy metals accumulation in soils poses a potential threat to ecosystems, which, in turn, threat human health through food chains. Therefore, remediating polluted sites is important to environment and humanity. In this investigation, statice (L. sinuatum) was exposed to Cd (0, 15, 30, 60 mg kg(-1) soil) or Pb (0, 100, 150, 300 mg kg(-1) soil) in a pot experiment to assess its tolerance to each metal and study its phytoaccumulation capability. The benefits of mycorrhization (mixture of Glomus mosseae and G. intraradices) were also studied simultaneously. Single exposure to Cd or Pb reduced the plant growth, but statice was still relatively tolerant to both metals. The plants accumulated both metals in their roots; little was translocated to the shoots. Total Pb and total Cd accumulated by the roots was approximately 2 and 3 times higher in mycorrhizal than non-mycorrhizal plants (49 versus 147 and 595 versus 956 µg plant(-1)) respectively; however, mycorrhization alleviated metal phytotoxicity. The results suggest that statice is a potential candidate to be used as an ornamental plant in lead and cadmium polluted sites, mainly inoculated with arbuscular mycorrhizae. Besides that, it would be useful as a Pb or Cd controlling agent by means of phytostabilization.

Effect of different strains of Agrobacterium rhizogenes and nature of explants on Plumbago indica hairy root culture with special emphasis on root biomass and plumbagin production.

The aim of the present study was to determine the effect of three strains of Agrobacterium rhizogenes (ATCC 15834, A4 and LBA 9402) and the nature of explants (leaf and stem) on hairy root induction, growth and plumbagin production in Plumbago indica. The first appearance of hairy roots, the transformation frequency, dry root biomass and plumbagin accumulation were found to be maximum in hairy roots induced in leaf explants infected with A. rhizogenes ATCC 15834 as compared with the other two bacterial strains. The hairy roots generated from stem explants infected with all three strains were not found to be productive in terms of the selected parameters. Finally, the insertion of the rolB gene of A. rhizogenes ATCC 15834 in hairy roots of P. indica derived from leaf explants was confirmed by PCR analysis.

Physical control of leafhoppers.

In 2000, a severe outbreak of phytoplasma-caused disease in Limonium spp. flowers devastated the industry in Israel; insecticides were not able to knock down and kill leafhopper vectors before they could transmit the pathogen. Nonchoice laboratory studies were conducted to determine the effect of UV-absorbing plastics on the movement of leafhoppers toward light; UV-absorbing plastic significantly reduced leafhopper movement. In choice trials conducted in sunlight, significantly more leafhoppers moved into the cage covered with regular plastic as opposed to the cage covered with UV-absorbing plastic. Field studies were conducted to determine at what height leafhoppers enter 2.5-3-m high walk-in tunnels; the majority enter the tunnels low to the ground, up to 1 m. Finally, field studies were conduced to compare leafhopper population levels in walk-in tunnels covered with UV-absorbing plastic or screening, and with ventilation holes at different heights above the ground. Elevated ventilation holes and UV-absorbing tunnel covering significantly reduced Orosius orientalis entrance into tunnels. Ramifications of these finding for leafhopper control are discussed.

Detection and molecular characterization of an aster yellows phytoplasma in poker statice and Queen Anne's lace in Alberta, Canada.

Queen Anne's lace and poker statice plants were found with a yellows-type disease with typical phytoplasma symptoms in an experimental farm near Brooks, Alberta in 1996. Phytoplasma bodies were detected by transmission electron microscopy in phloem cells of symptomatic plants, but not in healthy plants. The presence of a phytoplasma was confirmed by analysis with the polymerase chain reaction. Using a pair of universal primer sequences derived from phytoplasma 16S rRNA, an amplified product of the expected size (1.2 kb) was observed in samples from infected plants, but not in asymptomatic plants. Sequence analysis of the PCR products from the 16S/23S rDNA intergenic spacer region indicated that the two phytoplasma isolates in Queen Anne's lace and poker statice are genetically closely related to the western aster yellows phytoplasma.