Precipitation Reactions Between Components of Plant Tissue Extracts

Abstract

Precipitation lines are observed on gel-diffusion plates between many pairs of seed extracts. Interactions involving Canavalia ensiformis depend upon concanavalin A, and a number of extracts from other plant seeds contain a precipitant that mimics that lectin. Methyl a-D-mannopyranoside is a general inhibitor of the precipitation phenomenon and some form of protein-carbohydrate binding seems to be involved in all precipitations, although the exact nature of the macromolecules taking part is obscure. For the leguminous seeds Phaseolus vulgauis, Vicia faba and Cajanus cajan, precipitation reactions occur between extracts of cotyledons and extracts of tissues of the parent plants, even of the testa of the seeds. The nature of these reactions appears to be the same as those of the interspecies ones. Both types of reaction may be examples of ways in which plant cells recognize self from non-self. The material in P. vulgaris that reacts with concanavalin A is a group of globulin-like glycoproteins (5 % carbohydrate), heterogeneous in both charge and molecular weight but similar in overall amino acid analysis.