Fig. 2. Principal component analysis of amino acid mol% data in leaf phloem exudates sampled from potato plants grown under glass during sequential stages of plant development: `pre-tuber filling' and `tuber filling' (see text and Fig. 1 for explanation). (A) Attribute loadings on the first two components PC 1 and PC 2. Amino acid abbreviations are denoted in Table 1. (B) Plot of the sample scores on PC 1 and PC 2 which explain, respectively, 38.0% and 13.2% of the variation in the dataset.