Changes in Senecio grisebachii pyrrolizidine alkaloids abundances and profiles as response to soil quality

Senecio grisebachii Baker is an invasive weed considered to be toxic due to the presence of pyrrolizidine alkaloids (PA) in its tissues. The PA production by S. grisebachii aerial parts was evaluated in samples grown in two Argentinean Rolling Pampa fields with the same kind of soil but differing in the length of their exploitation period by conventional tillage practices and, consequently, in their deterioration level.We found significant differences in the relative concentrations of seven alkaloids between samples taken from the two fields. Seneciphylline was the most abundant alkaloid in inflorescences from less deteriorated soil (LD) while senecionine was the major one in those from highly deteriorated soil (D) being followed by seneciphylline, integerrimine, and minor amounts of spartiodine, jacobine, jacozine and retrorsine. A significant increase in total alkaloid content (TAC) was observed in inflorescences from samples growing in D soil (3.52±0.20 mg/g DW) when comparing with those from samples grown in LD one (3.23±0.26).