Table 2.

Pearson correlation coefficients between select ions from MBMS spectra of P. trichocarpa leaves from Clatskanie, OR and select metabolites as determined by GC/MS (based on area count) as well as lignin content, S/G ratios and the summation of metabolite-derived ions from MBMS spectra and the total aromatic metabolites in extract determined by GC/MS

Trait	Lignin content	S/G	Sum metabolite ions in MBMSa	Aromatics by GC/MS
m/z 64	− 0.34	0.02	0.68	0.65
m/z 65	− 0.38	0.32	0.74	0.69
m/z 66	− 0.54	0.32	0.87	0.80
m/z 68	− 0.49	0.30	0.71	0.59
m/z 77	− 0.64	0.38	0.98	0.85
m/z 78	− 0.43	0.23	0.72	0.66
m/z 91	− 0.39	0.25	0.68	0.59
m/z 92	− 0.32	0.25	0.61	0.53
m/z 94	− 0.55	0.35	0.93	0.85
m/z 105	− 0.66	0.35	0.98	0.85
m/z 106	− 0.52	0.40	0.77	0.68
m/z 107	− 0.59	0.36	0.96	0.82
m/z 108	− 0.65	0.45	0.95	0.84
m/z 110	− 0.26	− 0.06	0.61	0.60
m/z 122	− 0.65	0.39	0.98	0.86
m/z 181	− 0.19	0.38	0.59	0.55
2′-O-salicyloylsalicin	− 0.36	0.26	0.52	0.63
2,6-cyclohexadiene-1,2-diol	− 0.45	0.29	0.69	0.55
6-hydroxy-2-cyclohexenone alcohol	− 0.52	0.38	0.80	0.71
α-salicyloylsalicin	− 0.55	0.40	0.87	0.88
benzoyl-gentisyl alcohol	− 0.34	0.29	0.54	0.50
benzoyl-salicyloylsalicin	− 0.44	0.33	0.62	0.72
benzyl-coumaroyl-glucoside	− 0.53	0.31	0.76	0.74
catechol	− 0.53	0.36	0.80	0.77
coumaroyl-tremuloidin	− 0.45	0.25	0.67	0.65
phenethyl-tremuloidin	− 0.45	0.23	0.65	0.63
salicortin	− 0.50	0.33	0.83	0.81
benzyl-salicylic acid-2-O-glucoside	− 0.40	0.30	0.66	0.75
salicylic acid	− 0.45	0.25	0.68	0.61
salicyloyl-coumaroyl-glucoside conjugates	− 0.58	0.37	0.85	0.86
salicyltremuloidin	− 0.45	0.30	0.68	0.83
salireposide	− 0.42	0.26	0.68	0.67
sum metabolite ions in MBMSa	− 0.66	0.39	1.00	0.87
aromatics by GC/MS	− 0.54	0.32	0.87	1.00
tremulacin	− 0.52	0.38	0.77	0.85
tremuloidin	− 0.40	0.24	0.56	0.55
trichocarpin	− 0.43	0.32	0.68	0.67

^aMetabolite ion intensities summed 68, 71, 77, 91, 94, 105, 107, 108, and 122