Resistance to<i>Xanthomonas campestris</i>pv.<i>pelargonii</i>in geranium and diagnosis of the bacterial blight using polymerase chain reaction

Zhang, Shulu; Sairam, R. V.; Grefer, Doni; Feasel, James; Ferencak, Mark; Goldman, S. L.

doi:10.1080/03235400701622378

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…Reports of bacterial blight on walnut trees have increased but information about the causal pathogen is limited. Detection and identification of Xaj are based on isolations of the pathogen on selective medium, bioassays, and biochemical tests ( Loreti et al, 2015 ), and DNA-based molecular techniques ( Zhang et al, 2009 ).…”

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confidence: 99%

Identification and Characterization of Xanthomonas arboricola pv. juglandis Causing Bacterial Blight of Walnuts in Korea

et al. 2021

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The present study describes the bacterial blight of walnut, caused by Xanthomonas arboricola pv. juglandis ( Xaj ) in the northern Gyeongbuk province, Korea. Disease symptoms that appear very similar to anthracnose symptoms were observed in walnut trees in June 2016. Pathogens were isolated from disease infected leaves, fruits, shoots, bud, flower bud of walnut, and cultured onto yeast dextrose carbonate agar plates. Isolated bacteria with bacterial blight symptoms were characterized for their nutrient utilization profiles using Biolog GN2 and Vitek 2. In addition, isolates were subjected to physiological, biochemical, and morphological characterizations. Furthermore, isolates were identified using 16S rDNA sequence analysis, and multi-locus sequence analysis using atpD , dnaK , efp , and rpoD . To confirm pathogenicity, leaves, fruits, and stems of 3-year-old walnut plants were inoculated with bacterial pathogen suspensions as a foliar spray. One week after inoculation, the gray spots on leaves and yellow halos around the spots were developed. Fruits and stems showed browning symptoms. The pathogen Xaj was re-isolated from all symptomatic tissues to fulfill Koch’s postulates, while symptoms were not appeared on control plants. On the other hand, the symptoms were very similar to the symptoms of anthracnose caused by Colletotrichum gloeosporioides . When walnut plants were inoculated with combined pathogens of Xaj and C. gloeosporioides , disease symptoms were greater in comparison with when inoculated alone. Xaj population size was more in the month of April than March due to their dormancy in March, and sensitive to antibiotics such as oxytetracycline and streptomycin, while resistant to copper sulfate.

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confidence: 99%

Identification and Characterization of Xanthomonas arboricola pv. juglandis Causing Bacterial Blight of Walnuts in Korea

et al. 2021

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“…hortorum pv. pelargonii based on symptom expression alone after pathogen inoculation (Griesbach & Olbricht, 2002; Zhang, Sairam, et al, 2009). Five resistant pelargonium species were identified (Griesbach & Olbricht, 2002; Zhang, Sairam, et al, 2009), but most commercially important cultivars of Pelargonium zonale hybrids were highly susceptible (Griesbach & Olbricht, 2002; Zhang, Sairam, et al, 2009).…”

Section: Host Resistancementioning

confidence: 99%

Xanthomonas hortorum – beyond gardens: Current taxonomy, genomics, and virulence repertoires

Dia

Morinière

Cottyn³

et al. 2022

Molecular Plant Pathology

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Taxonomy Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Lysobacterales (earlier synonym of Xanthomonadales); Family Lysobacteraceae (earlier synonym of Xanthomonadaceae); Genus Xanthomonas; Species X. hortorum; Pathovars: pv. carotae, pv. vitians, pv. hederae, pv. pelargonii, pv. taraxaci, pv. cynarae, and pv. gardneri. Host range Xanthomonas hortorum affects agricultural crops, and horticultural and wild plants. Tomato, carrot, artichoke, lettuce, pelargonium, ivy, and dandelion were originally described as the main natural hosts of the seven separate pathovars. Artificial inoculation experiments also revealed other hosts. The natural and experimental host ranges are expected to be broader than initially assumed. Additionally, several strains, yet to be assigned to a pathovar within X. hortorum, cause diseases on several other plant species such as peony, sweet wormwood, lavender, and oak‐leaf hydrangea. Epidemiology and control X. hortorum pathovars are mainly disseminated by infected seeds (e.g., X. hortorum pvs carotae and vitians) or cuttings (e.g., X. hortorum pv. pelargonii) and can be further dispersed by wind and rain, or mechanically transferred during planting and cultivation. Global trade of plants, seeds, and other propagating material constitutes a major pathway for their introduction and spread into new geographical areas. The propagules of some pathovars (e.g., X. horturum pv. pelargonii) are spread by insect vectors, while those of others can survive in crop residues and soils, and overwinter until the following growing season (e.g., X. hortorum pvs vitians and carotae). Control measures against X. hortorum pathovars are varied and include exclusion strategies (i.e., by using certification programmes and quarantine regulations) to multiple agricultural practices such as the application of phytosanitary products. Copper‐based compounds against X. hortorum are used, but the emergence of copper‐tolerant strains represents a major threat for their effective management. With the current lack of efficient chemical or biological disease management strategies, host resistance appears promising, but is not without challenges. The intrastrain genetic variability within the same pathovar poses a challenge for breeding cultivars with durable resistance. Useful websites https://gd.eppo.int/taxon/XANTGA, https://gd.eppo.int/taxon/XANTCR, https://gd.eppo.int/taxon/XANTPE, https://www.euroxanth.eu, http://www.xanthomonas.org, http://www.xanthomonas.org/dokuwiki

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“…Symptoms are characterized by wilting of the plant, localized water‐soaked lesions that often become necrotic and rotted cuttings (Dougherly et al ., ; Nameth et al ., ).V‐shaped yellow areas in leaf margins are frequently observed. All commercial cultivars of Pelargonium × hortorum are susceptible to Xhp (Zhang et al ., ). Cuttings taken from infected mother‐plant stock are the main source of inoculum.…”

Section: Introductionmentioning

confidence: 97%

Virulence and in planta movement of Xanthomonas hortorum pv. pelargonii are affected by the diffusible signal factor (DSF)‐dependent quorum sensing system

Barel

Chalupowicz

Barash

et al. 2015

Molecular Plant Pathology

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Xanthomonas hortorum pv. pelargonii (Xhp), the causal agent of bacterial blight in pelargonium, is the most threatening bacterial disease of this ornamental worldwide. To gain an insight into the regulation of virulence in Xhp, we have disrupted the quorum sensing (QS) genes, which mediate the biosynthesis and sensing of the diffusible signal factor (DSF). Mutations in rpfF (encoding the DSF synthase) and rpfC (encoding the histidine sensor kinase of the two-component system RfpC/RpfG) and overexpression of rpfF showed a significant reduction in incidence and severity of the disease on pelargonium. Confocal laser scanning microscopy images of inoculated plants with a green fluorescent protein (GFP)-labelled wild-type strain showed that the pathogen is homogeneously dispersed in the lumen of xylem vessels, reaching the apex and invading the intercellular spaces of the leaf mesophyll tissue within 21 days. In contrast, the rpfF and rpfC knockout mutants, as well as the rpfF-overexpressing strain, remained confined to the vicinity of the inoculation site. The rpfF and rpfC mutants formed large incoherent aggregates in the xylem vessels that might interfere with upward movement of the bacterium within the plant. Both mutants also formed extended aggregates under in vitro conditions, whereas the wild-type strain formed microcolonies. Expression levels of putative virulence genes in planta were substantially reduced within 48 h after inoculation with the QS mutants when compared with the wild-type. The results presented indicate that an optimal DSF concentration is crucial for successful colonization and virulence of Xhp in pelargonium.

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Resistance toXanthomonas campestrispv.pelargoniiin geranium and diagnosis of the bacterial blight using polymerase chain reaction

Cited by 7 publications

References 10 publications

Identification and Characterization of Xanthomonas arboricola pv. juglandis Causing Bacterial Blight of Walnuts in Korea

Identification and Characterization of Xanthomonas arboricola pv. juglandis Causing Bacterial Blight of Walnuts in Korea

Xanthomonas hortorum – beyond gardens: Current taxonomy, genomics, and virulence repertoires

Virulence and in planta movement of Xanthomonas hortorum pv. pelargonii are affected by the diffusible signal factor (DSF)‐dependent quorum sensing system

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