Isolation of (2S,4R)-2-amino-4-methyl-hex-5-enoic acid, a nonprotein amino acid, as an allelochemical from the fruiting bodies of Boletus fraternus Peck.

Abstract

The mushroom Boletus fraternus Peck. shows allelopathy and suppresses the growth of broad leaf plants in nature. According to a bioassay-guided fractionation of the fruiting body of the fungus, a rare nonprotein amino acid was isolated as a major allelochemical. The chemical structure of the compound was determined to be (2S,4R)-2-amino-4-methyl-hex-5-enoic acid (5-dehydrohomoleucine) by analysis of 1 H-and 13 C-nuclear magnetic resonance spectra and comparison with data from the literature. The allelochemical caused 50% inhibition of lettuce seedling radicle growth at a concentration of 34 ppm (w/v). Further, since radicle growth was directed away from the filter paper to prevent contact with the allelochemical at concentrations higher than 300 ppm (w/v), the fungus may use the allelochemical to protect its immediate environment from contamination by other plants.

L-Canavanine, a Root Exudate From Hairy Vetch (Vicia villosa) Drastically Affecting the Soil Microbial Community and Metabolite Pathways

“…Few amino acids have been isolated and identified as intermediate compounds of biological phenomena such as allelopathy ( Araya et al, 2014 ). It may be because evaluating FAAs is challenging, since the concentration of FAAs available in plant roots and rhizosphere depends on many factors such as soil type ( Cao et al, 2016 ), soil pH ( Rothstein, 2010 ), temperature, elevation, and analytical methods ( Young et al, 1974 ; Chen et al, 2015 ).…”

“…Also, certain amino acids act as allelochemical or are involved in chemotaxis ( Fujii and Hiradate, 2007 ; Araya et al, 2014 ). Chemotaxis is a phenomenon by which the chemicals released from seeds stimulate the growth and trivial of the beneficial bacteria toward germinating seeds ( Harborne et al, 1971 ; Peters et al, 1986 ; Barbour et al, 1991 ).…”