1. Online Resource 3. EI mass spectra of unknown components 1-25. Mass spectra were deconvoluted from a GC/EI-QMS profile obtained from the polar fraction of a methoximated/trimethylsilylated root extract of Arabidopsis thaliana using AMDIS 2.7.

2. C 12 H 21 NO 3 Si 2 (1) RI(ALKANE) = 1062, RI(FAME) = 735

3. C 9 H 21 NO 2 Si (2) RI(ALKANE) = 1134, RI(FAME) = 811

4. C 8 H 21 NO 3 Si 2 (3) RI(ALKANE) = 1143, RI(FAME) = 820

5. C 11 H 27 NSi 2 (4) RI(ALKANE) = 1175, RI(FAME) = 854

6. C 12 H 20 N 2 O 2 Si (5) RI(ALKANE) = 1182, RI(FAME) = 860

7. C 10 H 24 O 4 Si 2 (6) RI(ALKANE) = 1214, RI(FAME) = 894

8. C 13 H 23 N 2 O 3 Si (7) RI(ALKANE) = 1254, RI(FAME) = 932

9. C 9 H 19 NO 2 Si (8) RI(ALKANE) = 1275, RI(FAME) = 954

10. C 11 H 25 O 4 Si 2 (9) RI(ALKANE) = 1419, RI(FAME) = 1097

11. C 10 H 23 O 4 Si 2 (10) RI(ALKANE) = 1443, RI(FAME) = 1122

12. C 12 H 30 N 2 OSi 2 (11) RI(ALKANE) = 1470, RI(FAME) = 1148

13. C 12 H 28 N 2 O 3 Si 3 (12) RI(ALKANE) = 1532, RI(FAME) = 1205

14. C 10 H 19 NS (13) RI(ALKANE) = 1647, RI(FAME) = 1320

15. C 11 H 11 N 2 O (14) RI(ALKANE) = 1758, RI(FAME) = 1427

16. C 15 H 34 O 5 Si 3 (15) RI(ALKANE) = 1806, RI(FAME) = 1477

17. C 16 H 34 O 7 Si 3 (16) RI(ALKANE) = 1886, RI(FAME) = 1561

18. C 16 H 36 O 6 Si 3 (17) RI(ALKANE) = 1888, RI(FAME) = 1562

19. C 21 H 52 O 5 SSi 5 (18) RI(ALKANE) = 2068, RI(FAME) = 1737

20. C 17 H 27 NO 5 Si 2 (19) RI(ALKANE) = 2072, RI(FAME) = 1741

21. C 14 H 18 N 2 OSi (20) RI(ALKANE) = 2096, RI(FAME) = 1770

22. C 9 H 19 NOSSi (21) RI(ALKANE) = 2111, RI(FAME) = 1784

23. C 23 H 48 O 4 Si (22) RI(ALKANE) = 2613, RI(FAME) = 2267

24. C 21 H 41 NO (23) RI(ALKANE) = 2655, RI(FAME) = 2309

25. C 25 H 52 O 4 Si (24) RI(ALKANE) = 2797, RI(FAME) = 2458

26. C 28 H 42 O 6 Si 2 (25) RI(ALKANE) = 2985, RI(FAME) = 2691