Contribution of the root cap to soil fertility: Extracellular plant lectins

Lectins are proteins with multiple sites that bind specific sugars and therefore can agglutinate cells or other substrates with those sugars on the surface. This property is exploited in detecting human ABO blood type, defined based on the presence of distinct surface sugars that result in agglutination of blood cells in response to appropriate lectins. This capacity to bind to specific sites on cell surfaces is of interest for its potential in treating human diseases including cancer, AIDS, and diabetes. In plants, species-specific lectins are secreted from root tips into the extracellular environment of agronomically important crops including legumes and cereals. The function, stability and distribution of these proteins after export from root cells into the extracellular environment remain unexplored. Experiments to examine predictions of the hypothesis that root-secreted lectins influence soil structure and fertility, rhizosphere microbial communities, and root nutrient cycling are warranted.