Bioactivity of the fungal metabolite (8R,16R)-(-)-pyrenophorin on graminaceous plants

Area of Science:

• Agricultural Science
• Mycology
• Plant Physiology

Background:

• Drechslera avenae is a pathogen with host specificity to wild oats (Avena sterilis).
• Secondary metabolites produced by plant pathogens can influence host-pathogen interactions and exhibit allelopathic effects.

Purpose of the Study:

• To isolate and identify a secondary metabolite from a specific Drechslera avenae pathotype.
• To investigate the bioactivity of the isolated compound, pyrenophorin, on the germination, growth, and chlorophyll metabolism of various graminaceous plants.

Main Methods:

• Isolation and identification of the secondary metabolite using standard chemical techniques.
• Bioassays to assess the effects of pyrenophorin on seed germination and root growth of Avena sterilis, A. fatua, A. sativa, Triticum aestivum, and Hordeum vulgare.
• Chlorophyll retention and dissipation assays in leaf sections of treated plants.

Main Results:

• The macrodiolide (8R,16R)-(-)-pyrenophorin was isolated and identified.
• Pyrenophorin inhibited seed germination of wild oats, oats, wheat, and barley at 60 microM.
• Root growth was differentially affected (stimulated, unaffected, or inhibited) by pyrenophorin concentrations from 10 to >51 microM.
• Abnormal chlorophyll retention was observed in leaf sections, and chlorophyll dissipation was reduced by pyrenophorin.

Conclusions:

• Pyrenophorin exhibits significant phytotoxicity, impacting germination and chlorophyll metabolism in graminaceous plants.
• The compound's effects on root growth are concentration-dependent.
• Findings provide insights into the allelopathic potential of fungal secondary metabolites and their ecological roles.