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The sunflower downy mildew pathogen Plasmopara halstedii.
Mol Plant Pathol 2015; 16(2):109-22MP

Abstract

Downy mildew of sunflower is caused by Plasmopara halstedii (Farlow) Berlese & de Toni. Plasmopara halstedii is an obligate biotrophic oomycete pathogen that attacks annual Helianthus species and cultivated sunflower, Helianthus annuus. Depending on the sunflower developmental stage at which infection occurs, the characteristic symptoms range from young seedling death, plant dwarfing, leaf bleaching and sporulation to the production of infertile flowers. Downy mildew attacks can have a great economic impact on sunflower crops, and several Pl resistance genes are present in cultivars to protect them against the disease. Nevertheless, some of these resistances have been overcome by the occurrence of novel isolates of the pathogen showing increased virulence. A better characterization of P. halstedii infection and dissemination mechanisms, and the identification of the molecular basis of the interaction with sunflower, is a prerequisite to efficiently fight this pathogen. This review summarizes what is currently known about P. halstedii, provides new insights into its infection cycle on resistant and susceptible sunflower lines using scanning electron and light microscopy imaging, and sheds light on the pathogenicity factors of P. halstedii obtained from recent molecular data.

TAXONOMY

Kingdom Stramenopila; Phylum Oomycota; Class Oomycetes; Order Peronosporales; Family Peronosporaceae; Genus Plasmopara; Species Plasmopara halstedii.

DISEASE SYMPTOMS

Sunflower seedling damping off, dwarfing of the plant, bleaching of leaves, starting from veins, and visible white sporulation, initially on the lower side of cotyledons and leaves. Plasmopara halstedii infection may severely impact sunflower seed yield.

INFECTION PROCESS

In spring, germination of overwintered sexual oospores leads to sunflower root infection. Intercellular hyphae are responsible for systemic plant colonization and the induction of disease symptoms. Under humid and fresh conditions, dissemination structures are produced by the pathogen on all plant organs to release asexual zoosporangia. These zoosporangia play an important role in pathogen dissemination, as they release motile zoospores that are responsible for leaf infections on neighbouring plants.

DISEASE CONTROL

Disease control is obtained by both chemical seed treatment (mefenoxam) and the deployment of dominant major resistance genes, denoted Pl. However, the pathogen has developed fungicide resistance and has overcome some plant resistance genes. Research for more sustainable strategies based on the identification of the molecular basis of the interaction are in progress.

USEFUL WEBSITES

http://www.heliagene.org/HP, http://lipm-helianthus.toulouse.inra.fr/dokuwiki/doku.php?id=start, https://www.heliagene.org/PlasmoparaSpecies (soon available).

Authors+Show Affiliations

INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326, Castanet-Tolosan, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, F-31326, Castanet-Tolosan, France.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25476405

Citation

Gascuel, Quentin, et al. "The Sunflower Downy Mildew Pathogen Plasmopara Halstedii." Molecular Plant Pathology, vol. 16, no. 2, 2015, pp. 109-22.
Gascuel Q, Martinez Y, Boniface MC, et al. The sunflower downy mildew pathogen Plasmopara halstedii. Mol Plant Pathol. 2015;16(2):109-22.
Gascuel, Q., Martinez, Y., Boniface, M. C., Vear, F., Pichon, M., & Godiard, L. (2015). The sunflower downy mildew pathogen Plasmopara halstedii. Molecular Plant Pathology, 16(2), pp. 109-22. doi:10.1111/mpp.12164.
Gascuel Q, et al. The Sunflower Downy Mildew Pathogen Plasmopara Halstedii. Mol Plant Pathol. 2015;16(2):109-22. PubMed PMID: 25476405.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The sunflower downy mildew pathogen Plasmopara halstedii. AU - Gascuel,Quentin, AU - Martinez,Yves, AU - Boniface,Marie-Claude, AU - Vear,Felicity, AU - Pichon,Magalie, AU - Godiard,Laurence, Y1 - 2014/12/04/ PY - 2014/12/6/entrez PY - 2014/12/6/pubmed PY - 2015/9/29/medline KW - Helianthus annuus KW - Plasmopara halstedii KW - effectors KW - infection modes KW - life cycle KW - obligate biotroph oomycete KW - pathogen virulence SP - 109 EP - 22 JF - Molecular plant pathology JO - Mol. Plant Pathol. VL - 16 IS - 2 N2 - UNLABELLED: Downy mildew of sunflower is caused by Plasmopara halstedii (Farlow) Berlese & de Toni. Plasmopara halstedii is an obligate biotrophic oomycete pathogen that attacks annual Helianthus species and cultivated sunflower, Helianthus annuus. Depending on the sunflower developmental stage at which infection occurs, the characteristic symptoms range from young seedling death, plant dwarfing, leaf bleaching and sporulation to the production of infertile flowers. Downy mildew attacks can have a great economic impact on sunflower crops, and several Pl resistance genes are present in cultivars to protect them against the disease. Nevertheless, some of these resistances have been overcome by the occurrence of novel isolates of the pathogen showing increased virulence. A better characterization of P. halstedii infection and dissemination mechanisms, and the identification of the molecular basis of the interaction with sunflower, is a prerequisite to efficiently fight this pathogen. This review summarizes what is currently known about P. halstedii, provides new insights into its infection cycle on resistant and susceptible sunflower lines using scanning electron and light microscopy imaging, and sheds light on the pathogenicity factors of P. halstedii obtained from recent molecular data. TAXONOMY: Kingdom Stramenopila; Phylum Oomycota; Class Oomycetes; Order Peronosporales; Family Peronosporaceae; Genus Plasmopara; Species Plasmopara halstedii. DISEASE SYMPTOMS: Sunflower seedling damping off, dwarfing of the plant, bleaching of leaves, starting from veins, and visible white sporulation, initially on the lower side of cotyledons and leaves. Plasmopara halstedii infection may severely impact sunflower seed yield. INFECTION PROCESS: In spring, germination of overwintered sexual oospores leads to sunflower root infection. Intercellular hyphae are responsible for systemic plant colonization and the induction of disease symptoms. Under humid and fresh conditions, dissemination structures are produced by the pathogen on all plant organs to release asexual zoosporangia. These zoosporangia play an important role in pathogen dissemination, as they release motile zoospores that are responsible for leaf infections on neighbouring plants. DISEASE CONTROL: Disease control is obtained by both chemical seed treatment (mefenoxam) and the deployment of dominant major resistance genes, denoted Pl. However, the pathogen has developed fungicide resistance and has overcome some plant resistance genes. Research for more sustainable strategies based on the identification of the molecular basis of the interaction are in progress. USEFUL WEBSITES: http://www.heliagene.org/HP, http://lipm-helianthus.toulouse.inra.fr/dokuwiki/doku.php?id=start, https://www.heliagene.org/PlasmoparaSpecies (soon available). SN - 1364-3703 UR - https://www.unboundmedicine.com/medline/citation/25476405/The_sunflower_downy_mildew_pathogen_Plasmopara_halstedii_ L2 - https://doi.org/10.1111/mpp.12164 DB - PRIME DP - Unbound Medicine ER -