Avocado roots treated with salicylic acid produce phenol-2,4-bis (1,1-dimethylethyl), a compound with antifungal activity.
We demonstrated the ability of salicylic acid (SA) to induce a compound in avocado roots that strengthens their defense against Phytophthora cinnamomi. The SA content of avocado roots, before and after the application of exogenous SA, was determined by High-Performance Liquid Chromatography (HPLC). After 4h of SA feeding, the endogenous level in the roots increased to 223 μg g(-1) FW, which was 15 times the amount found in control roots. The methanolic extract obtained from SA-treated avocado roots inhibited the radial growth of P. cinnamomi. A thin layer chromatographic bioassay with the methanolic extract and spores of Aspergillus showed a distinct inhibition zone. The compound responsible for the inhibition was identified as phenol-2,4-bis (1,1-dimethylethyl) by gas chromatography and mass spectrometry. At a concentration of 100 μg/mL, the substance reduced germinative tube length in Aspergillus and radial growth of P. cinnamomi. A commercial preparation of phenol-2,4-bis (1,1-dimethylethyl) caused the same effects on mycelium morphology and radial growth as our isolate, confirming the presence of this compound in the root extracts. This is the first report of the induction of this compound in plants by SA, and the results suggest that it plays an important role in the defense response of avocado.
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1', Morelia, Michoacán CP 58040, Mexico.
Gerardo
G
Rangel-Sánchez
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1', Morelia, Michoacán CP 58040, Mexico.
Elda
E
Castro-Mercado
Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Edif. A1', Morelia, Michoacán CP 58040, Mexico. Electronic address: egpineda@umich.mx.
Ernesto
E
García-Pineda
D000935:Antifungal Agents / Q000378:metabolism* / Q000494:pharmacology*; D001230:Aspergillus / Q000187:drug effects*; D027421:Persea / Q000187:drug effects* / Q000378:metabolism*; D010838:Phytophthora / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology*
D000935:Antifungal Agents; D020156:Salicylic Acid
Aspergillus; Avocado; Phenol-2,4-bis(1,1-dimethylethyl); Phytophthora cinnamomi; Salicylic acid