Phomalactone from a Phytopathogenic Fungus Infecting ZINNIA elegans (ASTERACEAE) Leaves
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Zinnia elegans Jacq. plants are infected by a fungus that causes dark red spots with necrosis on leaves, particularly in late spring to the middle of summer in the Mid-South of the United States. This fungal disease causes the leaves to wilt and eventually kills the plant. The fungus was isolated, cultured in potato dextrose broth, and identified as Nigrospora sphaerica by molecular techniques. Two major lactone metabolites (phomalactone and catenioblin A) were isolated from liquid culture of N. sphaerica isolated from Z. elegans. When injected into leaves of Z. elegans, phomalactone caused lesions similar to those of the fungus. The lesion sizes were proportional to the concentration of the phomalactone. Phomalactone, but not catenioblin A, was phytotoxic to Z. elegans and other plant species by inhibition of seedling growth and by causing electrolyte leakage from photosynthetic tissues of both Z. elegans leaves and cucumber cotyledons. This latter effect may be related to the wilting caused by the fungus in mature Z. elegans plants. Phomalactone was moderately fungicidal to Coletotrichum fragariae and two Phomopsis species, indicating that the compound may keep certain other fungi from encroaching into plant tissue that N. sphaerica has infected. Production of large amounts of phomalactone by N. sphaerica contributes to the pathogenic behavior of this fungus, and may have other ecological functions in the interaction of N. sphaerica with other fungi. This is the first report of isolation of catenioblin A from a plant pathogenic fungus. The function of catenioblin A is unclear, as it was neither significantly phyto- nor fungitoxic.
KeywordsPhomalactone Catenioblin A Phytotoxin Asteraceae Nigrospora sphaerica Zinnia elegans
We thank Jason Martin, Eric Briscoe, Linda Robertson and Ramona Pace for technical assistance.
- Dayan FE, Duke SO (2010) Protoporphyrinogen oxidase-inhibiting herbicides. In: Krieger RK, Doull J, Hodgson E, Maibach H, Reiter L, Ross J, Slikker WJ, Van Hemmon J (eds) Haye’s handbook of pesticide toxicology, vol 2, 3rd edn, Agents. Academic, Elsevier, San Diego, CA, pp 1733–1751CrossRefGoogle Scholar
- Duke SO, Kenyon WH (1993) Peroxidizing activity determined by cellular leakage. In: Böger P, Sandmann G (eds) Target assays for modern herbicides and related phytotoxic compounds. CRC Press, Boca Raton, FL, pp 61–66Google Scholar
- Evidente A (2006) Chemical and biological characterization of toxins produced by weed pathogenic fungi as potential natural herbicides. Amer Chem Soc Symp Ser 927:62–75Google Scholar
- Macias-Rubalcava ML, Hernandez-Bautista BE, Jimenez-Estrada M, Gonzalez MC, Glenn AE, Hanlin RT, Hernandez-Ortega S, Saucedo-Garcia A, Muria-Gonzalez JM, Anaya AL (2008) Napthoquinone spiroketal with allelochemical activity from the newly discovered endophytic fungus Edenia gomezpomae. Phytochemistry 69:1185–1196PubMedCrossRefGoogle Scholar
- Sauter H (2012) Strobilurins and other complex III inhibitors. In Modern crop protection compounds (2nd Edt.) W. Kraemer, ed., Wiley-VCH Verlag GmbH & Co., KGaA, Weinheim, Germany, pp. 584–627.Google Scholar
- Soytong K, Sibounnavong P, Kanokmedhakul K, Kanokmedhakul S (2014) Biological active compounds of Scleroderma citrinum that inhibit plant pathogenic fungi. J Agric Technol 10:79–86Google Scholar
- Wedge DE, Kuhajek JM (1998) A microbioassay for fungicide discovery. SAAS Bull Biochem Biotechnol 11:1–7Google Scholar
- White TJ, Bruns T, Lee S, Taylor J (1990) Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In PCR Protocols: A guide to Methods and Applications. 315–322. Academic Press: San Diego, USAGoogle Scholar
- Yamamoto I, Suide H, Hemmi T, Yamano T (1970) Antimicrobial α, β-unsaturated δ-lactones from molds. Takeda Kenkyusho Ho 29:1–10Google Scholar