N levels in MMP1 phloem exudate and leaves, and expression of genes involved in amino acid synthesis and transport in leaves. A, Total free amino acid levels in the phloem of MMP1 compared with wild-type (WT) plants. B, Amino acid composition and concentration in the phloem exudates. Hse, Homo-Ser. C, Total N levels in leaves. D, Total free amino acid levels in leaves. DW, Dry weight. E, Amino acid composition and concentration in leaves. F, Fold change in gene expression of pea GS1, GS2, and GS3, AS1, and amino acid transporters AAP1, AAP2, and CAT6. Degenerated primers were used for ferredoxin-dependent Glu synthase [GOGAT (Fd)] and ASNase. Results are presented as means ± sd. Asterisks indicate significant differences from the wild type detected by Student’s t test (n = 4): * P < 0.05, ** P < 0.01, *** P < 0.001.