The Role of Lectin in Association Between Rice and Nitrogen-Fixing Bacteria.

Lectins are multivalent carbohydrate-binding proteins and glycoproteins. In rice and other cereal crops, lectins are well characterized for their binding specificity to N-acetylglucosamine or its oligomers. Although the natural function of lectin remains unknown, several possible functions of cereal lectins have been proposed including an involvement in plantmicrobial interaction. We found that rice lectins are not exclusively confined to embryo, but also in seedling leaf and root, especially at the root tip, and opening stoma of young leaf, which are preferent adhesion sites of microbes. Lectin contents varied with developmental stage and environmental factors. Different rice varieties contain different amount of lectin and respond differently to inoculation by associative nitrogen-fixing Klebsiella R15 and R17. Better plant growth promotion and associative nitrogen-fixation were observed in high lectin variety. Colonization of bacteria on the root surface increased the root lectin. Our results support for the potential application of nitrogen-fixing Klebsiella for promotion of growth and associative nitrogen fixation in rice, Oryza sativa L. [ABSTRACT FROM AUTHOR]