Collection of Pure Phloem Sap from Wheat and its Chemical Composition

Wheat Phloem sap was collected without contamination from thestylets of small brown planthopper severed by a YAG laser beam.The sugar, amino acid and inorganic ion composition was determinedusing only one µl of the sap. The sap had a high sucrose level (251 mM), and also a high K⁺level (299 mM). Total amino acid compounds in the sap reached262 mM. The dominant amino acids were glutamic acid, asparticacid and serine, while r-amino butylic acid was absent. Themajor anion in the sap was Cl^– and its concentration was25.1 mM. Nitrate was also present at a concentration of 8.1mM. These results suggested that the sap obtained from the cut endof the stylets of the small brown planthopper was a phloem originof wheat. (Received May 21, 1986; Accepted August 7, 1986)