Advances in Long Distance Transport of RNA Molecules in Plant Phloem Advances in Long Distance Transport of RNA Molecules in Plant Phloem Analysis of sugars in cassava phloem sap by HPLC-ELSD detection Influence of Organic and Inorganic Nitrogen Supply on the Composition of Tomato Seedling Root Exudates, Xylem and Phloem Sap Grown in Hydroponic Culture