Table II. PLS regression analysis of the relation between low molecular weight metabolites and biomass, starch level, or protein concentration

PLS was performed using 52 metabolic traits from condition A as input and FW, starch, or protein as output traits from condition B, for each of the nine combinations of conditions A and B. The correlation between the predicted values and the response variables, denoted by R, was determined after cross-validated selection of the number of latent variables (n). The number of latent variables (n) and the P values were determined in two successive and independent rounds of cross validation, and significance was then determined by permutation test (see “Materials and Methods”). PLS was also performed on the means of traits across the three growth conditions, and on a combined data set containing all individual values from the three growth conditions; in these regressions, growth conditions are not given because the output traits were averaged or combined, respectively, across all three growth conditions. Italic font indicates regressions in which the input and output traits are from the same growth condition. Significant regressions are indicated by boldface.

Growth ConditionOutput Trait12hHN12hLN8hHNMeanCombination of All Individual Values
R/nPR/nPR/nPR/nPR/nP
12hHNFW0.36/10.0020.26/10.0060.28/10.002
Starch0.67/10.0010.47/10.0010.68/10.001
Protein0.46/10.0010.34/10.0010.46/10.001
12hLNFW0.51/10.0010.58/10.0010.51/10.001
Starch0.35/10.0010.39/10.0010.36/30.001
Protein0.45/10.0010.57/20.0010.34/10.002
8hHNFW0.27/10.0030.21/10.0230.27/10.013
Starch0.26/10.0060.05/20.3020.23/10.023
Protein0.13/10.1020.17/10.0570.17/10.072
Mean or AllFW0.45/10.0010.73/30.001
Starch0.61/20.0010.77/310.001
Protein0.57/30.0010.94/320.001