A minimum essential structure of LN-3 elicitor activity in bean cotyledons.

A great deal of an elicitor-active oligosaccharide (1.47 g) was obtained from 40 g of polysaccharide laminaran with the guidance of elicitor activity in the bean cotyledon assay. Physicochemical means suggested that the oligosaccharide was a beta-1,3- and beta-1,6-linked triglucoside. This was a partial structure of LN-3, having elicitor activity to alfalfa and bean. The triglucoside exhibited a specific elicitor activity to bean, not to alfalfa and pea. The highly digested hydrolysate containing monomer and dimers as major components did not show elicitor activity in the bean cotyledon assay. The structural feature was essential for elicitation of phytoalexin accumulation in bean cotyledons. These results suggested that this triglucoside had a specific elicitor activity and a minimum elicitor-active entity to bean cotyledons.