Beta (Î²) -alanine is a naturally occurring non-proteingenic amino acid. Î²-alanine suppressed the growth activities of sugar beet pathogens Rhizoctonia solani Kuhn (AG2-2), Sclerotium rolfsii Sacc. and Fusarium solani (Mart) Sacc.when applied to the growth medium at different concentrations (12.5-100 µg/ ml).When applied to soil, Î²-alanine suppressed fungal infection of two sugar beet cultivars Raspoly and TOP. In absence of Î²-alanine, R. solani was the most virulent against cvs. Raspoy and TOP. Virulence was directly correlated with the activities of cell wall-degrading enzymes produced by these pathogens in vivo. Reduced virulence of R. solani, S. rolfsii and F. solani under Î²-alanine stress was due to decreased inoculum potential of the pathogens as result of the reduction of the cell wall-degrading enzymes. Growth parameters including emergence, plant length and dry weight of sugar beet were significantly increased at all investigated Î²-alanine concentrations .The infection rate was significantly decreased with increasing Î²-alanine stress, whereas the total sugar reducing values (TRV) was significantly increased in the tested sugar beet cultivars. The results indicated the possibility of the tested amino acid for protection of sugar beet plant cultivars against fungal infection.
Sugar beet pathogens, Î²-alanine, growth activities, cell wall-degrading enzymes, sugar contents .