Production of phytoalexins in peanut (Arachis hypogaea) seed elicited by selected microorganisms

Authors: Sobolev, Victor

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2013
Publication Date: 2/18/2013
Citation: Sobolev, V.S. 2013. Production of phytoalexins in peanut (Arachis hypogaea) seed elicited by selected microorganisms. J. Agric. Food Chem. 61(8):1850-1858.

Interpretive Summary: Plants accumulate defensive antibiotic chemicals, phytoalexins in response to the presence of microscopic pathogens, which in turn produce phytoalexin-detoxification proteins for successfully invading the plant host. The degradation of peanut phytoalexins by pathogenic fungi (molds) to nontoxic to these fungi compounds has been investigated. Important to the peanut plant fungi, in contrast to bacteria, were demonstrated to utilize a mechanism for effective peanut phytoalexin degradation. Clarification of the phytoalexin detoxification mechanism involved in infection of peanuts by fungi could provide approaches for preventing the plant invasion by the fungi that cause peanut diseases and contaminate seeds with compounds toxic to humans and animals.

Technical Abstract: Plants accumulate defensive phytoalexins in response to the presence of pathogens, which in turn produce phytoalexin-detoxification enzymes for successfully invading the plant host. The detoxification of a number of phytoalexins by phytopathogenic fungi has been elucidated for various host plant families. However, detoxification of peanut prenylated stilbenoid phytoalexins has not been reported. Present study revealed that Aspergillus spp. from section Flavi were capable of degrading one of the major peanut phytoalexin, arachidin-3, into its oxidized homologue, arachidin-1 and a benzenoid, SB-1. However, A. niger from section Nigri as well as other fungal and bacterial species tested, were incapable of changing the structure of arachidin-3. None of the species tested, with the exception of a Cladosporium sp. and Rhizobium leguminosarum, were able to degrade SB-1. Elucidation of the phytoalexin detoxification system involved in infection of peanut by important Aspergillus spp. could provide strategies for preventing plant invasion by the fungi that produce aflatoxins.