28. Hartmann T, Toppel G (1987) Senecionine N-oxide, the primary product of pyrrolizidine
alkaloid biosynthesis in root cultures of Senecio vulgaris. Phytochemistry 26:1639–1643
29. Hartmann T, Zimmer M (1986) Organ-specific distribution and accumulation of pyrrolizidine
alkaloids during the life-history of 2 annual Senecio species. J Plant Physiol 122:67–80
30. Pelser PB, de Vos H, Theuring C, Beuerle T, Vrieling K, Hartmann T (2005) Frequent gain and
loss of pyrrolizidine alkaloids in the evolution of Senecio section Jacobaea (Asteraceae).
Phytochemistry 66:1285–1295
31. Hartmann T, Ehmke A, Eilert U, von Borstel K, Theuring C (1989) Sites of synthesis,
translocation and accumulation of pyrrolizidine alkaloid N-oxides in Senecio vulgaris L. Planta
177:98–107
32. Hartmann T, Dierich B (1998) Chemical diversity and variation of pyrrolizidine alkaloids of the
senecionine type: biological need or coincidence? Planta 206:443–451
33. Bottcher F, Adolph RD, Hartmann T (1993) Homospermidine synthase, the 1st pathwayspecific enzyme in pyrrolizidine alkaloid biosynthesis. Phytochemistry 32:679–689
34. Ober D, Hartmann T (1999) Homospermidine synthase, the first pathway-specific enzyme
of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase. In: Proceedings
of the National Academy of Sciences of the United States of America, vol 96, pp 14777–14782
35. Reimann A, Nurhayati N, Backenkohler A, Ober D (2004) Repeated evolution of the
pyrrolizidine alkaloid-mediated defense system in separate angiosperm lineages. Plant Cell
16:2772–2784
36. Schaffner U, Vrieling K, van der Meijden E (2003) Pyrrolizidine alkaloid content in Senecio:
ontogeny and developmental constraints. Chemoecology 13:39–46
37. Sander H, Hartmann T (1989) Site of synthesis, metabolism and translocation of senecionine
N-oxide in cultured roots of Senecio erucifolius. Plant Cell Tissue Org Cult 18:19–31
38. Witte L, Ernst L, Adam H, Hartmann T (1992) Chemotypes of 2 pyrrolizidine alkaloidcontaining Senecio species. Phytochemistry 31:559–565
39. Vrieling K, de Boer N (1999) Host-plant choice and larval growth in the cinnabar moth: do
pyrrolizidine alkaloids play a role? Entomol Exp Appl 91:251–257
40. de Boer NJ (1999) Pyrrolizidine alkaloid distribution in Senecio jacobaea rosettes minimises
losses to generalist feeding. Entomol Exp Appl 91:169–173
41. Vrieling K, Derridj S (2003) Pyrrolizidine alkaloids in and on the leaf surface of Senecio
jacobaea L. Phytochemistry 64:1223–1228
42. Vrieling K, van wijk CAM (1994) Cost assessment of the production of pyrrolizidine alkaloids
in ragwort (senecio jacobaea L.). Oecologia 97:541–546
43. Hol WHG, Vrieling K, van Veen JA (2003) Nutrients decrease pyrrolizidine alkaloid concentrations in Senecio jacobaea. New Phytol 158:175–181
44. Cheng D, Nguyen VT, Ndihokubwayo N, Ge J, Mulder PPJ (2017) Pyrrolizidine alkaloid
variation in Senecio vulgaris populations from native and invasive ranges. PeerJ 5:e3686
45. Brooks JS, Feeny P (2004) Seasonal variation in Daucus carota leaf-surface and leaf-tissue
chemical profiles. Biochem Syst Ecol 32:769–782
11 Variation in Leaf-Surface and Leaf-Tissue Secondary Metabolites:. . .
261
alkaloid biosynthesis in root cultures of Senecio vulgaris. Phytochemistry 26:1639–1643
29. Hartmann T, Zimmer M (1986) Organ-specific distribution and accumulation of pyrrolizidine
alkaloids during the life-history of 2 annual Senecio species. J Plant Physiol 122:67–80
30. Pelser PB, de Vos H, Theuring C, Beuerle T, Vrieling K, Hartmann T (2005) Frequent gain and
loss of pyrrolizidine alkaloids in the evolution of Senecio section Jacobaea (Asteraceae).
Phytochemistry 66:1285–1295
31. Hartmann T, Ehmke A, Eilert U, von Borstel K, Theuring C (1989) Sites of synthesis,
translocation and accumulation of pyrrolizidine alkaloid N-oxides in Senecio vulgaris L. Planta
177:98–107
32. Hartmann T, Dierich B (1998) Chemical diversity and variation of pyrrolizidine alkaloids of the
senecionine type: biological need or coincidence? Planta 206:443–451
33. Bottcher F, Adolph RD, Hartmann T (1993) Homospermidine synthase, the 1st pathwayspecific enzyme in pyrrolizidine alkaloid biosynthesis. Phytochemistry 32:679–689
34. Ober D, Hartmann T (1999) Homospermidine synthase, the first pathway-specific enzyme
of pyrrolizidine alkaloid biosynthesis, evolved from deoxyhypusine synthase. In: Proceedings
of the National Academy of Sciences of the United States of America, vol 96, pp 14777–14782
35. Reimann A, Nurhayati N, Backenkohler A, Ober D (2004) Repeated evolution of the
pyrrolizidine alkaloid-mediated defense system in separate angiosperm lineages. Plant Cell
16:2772–2784
36. Schaffner U, Vrieling K, van der Meijden E (2003) Pyrrolizidine alkaloid content in Senecio:
ontogeny and developmental constraints. Chemoecology 13:39–46
37. Sander H, Hartmann T (1989) Site of synthesis, metabolism and translocation of senecionine
N-oxide in cultured roots of Senecio erucifolius. Plant Cell Tissue Org Cult 18:19–31
38. Witte L, Ernst L, Adam H, Hartmann T (1992) Chemotypes of 2 pyrrolizidine alkaloidcontaining Senecio species. Phytochemistry 31:559–565
39. Vrieling K, de Boer N (1999) Host-plant choice and larval growth in the cinnabar moth: do
pyrrolizidine alkaloids play a role? Entomol Exp Appl 91:251–257
40. de Boer NJ (1999) Pyrrolizidine alkaloid distribution in Senecio jacobaea rosettes minimises
losses to generalist feeding. Entomol Exp Appl 91:169–173
41. Vrieling K, Derridj S (2003) Pyrrolizidine alkaloids in and on the leaf surface of Senecio
jacobaea L. Phytochemistry 64:1223–1228
42. Vrieling K, van wijk CAM (1994) Cost assessment of the production of pyrrolizidine alkaloids
in ragwort (senecio jacobaea L.). Oecologia 97:541–546
43. Hol WHG, Vrieling K, van Veen JA (2003) Nutrients decrease pyrrolizidine alkaloid concentrations in Senecio jacobaea. New Phytol 158:175–181
44. Cheng D, Nguyen VT, Ndihokubwayo N, Ge J, Mulder PPJ (2017) Pyrrolizidine alkaloid
variation in Senecio vulgaris populations from native and invasive ranges. PeerJ 5:e3686
45. Brooks JS, Feeny P (2004) Seasonal variation in Daucus carota leaf-surface and leaf-tissue
chemical profiles. Biochem Syst Ecol 32:769–782
11 Variation in Leaf-Surface and Leaf-Tissue Secondary Metabolites:. . .
261