Chemical defense of leguminosae. are quinolizidine alkaloids part of the antimicrobial defense system of lupins?

Abstract

Growth of 6 bacteria (Serratia marcescens, Bacillus megaterium, Bacillus subtilis, Streptococcus viridis, Micrococcus luteus, and Mycobacterium phlei) was inhibited by 50% if the growth medium contained sparteine at concentrations between 0.5 -10 mM. Total growth inhibition, which was bacteriostatic in nature, was achieved at 20 mM. The growth of 6 phytopathogenic fungi was also affected: At a sparteine concentration of 15 mM the growth of Alternaria porri was reduced by 40% as compared to the untreated control. Respective values were 18% inhibition for Piricularia oryzae, 33% for Helminthosporium carbonum, 15% for R hizoctonia solani, 5% for Fusarium oxysporum, and 42% for Asperquillus oryzae. Since the concentrations of quinolizidine alkaloids range from 1-200 mM (roots, leaves, or stems) or 10 -200 mmol/kg (seeds) in Leguminosae, it is discussed whether quinolizidine alkaloids are involved in the antimicrobial defense of lupins, in addition to their potential role as allelopathic or herbivore repellent defense compounds. © 1984, Walter de Gruyter. All rights reserved.