Identification of amino acids and sugars in root exudate of mungbean (Vigna radiata L.)

Abstract

Root exudates represent an important source of nutrient for microorganisms in the rhizosphere and seem to participate in early colonization inducing chemotactic responses of rhizospheric bacteria. Plant root exudates consist of a complex mixture of organic acid anions, phytosiderophores, sugars,vitamins, amino acids, purines, nucleosides, inorganic ions (e.g. HCO3−, OH−, H+), gaseous molecules (CO2,H2), enzymes and root border cells which have major direct or indirect effects on the acquisition of mineral nutrients required for plant growth. Root exudates have traditionally been grouped into low- and high-molecular weight compounds. For the search of primary metabolites (amino acids and sugar) in root exudate, mung bean (Vigna radiata L. var. HUM 1) was grown in Thronton’s media for 30 days in culture tube. Bradyrhizobium (strain MO5) was used for nodulation in mung bean. The root exudates in media (500mL) were collected and concentrated for the identification of primary metabolites (amino acids and sugars) through paper chromatography. The amino acids identified in root exudates of mung bean (Vigna radiata L.) were glutamic acid, proline, hydroxyl proline and threonine and the sugars identified were rhamnose, arabinose and D-ribose.