Composition and Transport of Amino Acids in Wheat Plant during Grain Development

Contents and composition of amino acids in grain, liquid in endosperm cavity ,phloem exudate from peduncle, flag leaf, phloem exudate from flag leaf and xylem sap from roots were measured during grain development, using Triticum aestivum L. cv. Jingdong 6. The main amino acids were Gln+Glu,Pro,Ala,Asn+Asp,Ser and Gly in grain. Rate of Ala,γ Aba, Ser, Glnand Gly were ranged from 1% to 18% and were main amino acids in grain endosperm cavity. 70% of the amino acids in phloem exudate from peduncle were Asn, Thr, Ala, Ser and Gln. In flag leaf, the main amino acids were Ala, Asn, Ser, Val, Pro, Gly, Thr, Asp. But in phloem exudate from flag leaf, Gln was more than 20% of the total, and Ala,Asn, Ser, Val, Pro, Gly, Thr, Asp were also main amino acids. In xylem sap transported from roots to shoots, Gln was the maximum, while rates of Ala, Ser, Thr and Val were more than 5%. It was indicated that grain selectively absorbed amino acids, transportation and transformation of amino acids within the whole plant were active. A model for amino acid transportation and transformation within the whole plant was proposed.