Impact of temperature stress on secondary metabolite profile and phytotoxicity of Amaranthus cruentus L. leaf extracts | Vpliv temperaturnega stresa na profil in fitotoksičnost sekundarnih metabolitov v listnem izvlečku zrnatega ščira (Amaranthus cruentus L.)

English. In this study Amaranthus cruentus plants were grown under controlled optimal conditions (28/21 °C) for three months and then subjected to cold (14/7 °C) and hot (33/40 °C) temperatures. We investigated the influence of these temperature regimes on the metabolite profile of the leaves through analyses of data by TLC, HPLC and GC-MS spectrometry. The phytotoxic potential of a methanol-water (MW) and dichloromethane (DCM) extract from the aerial parts were examined through in vitro screening of germination and growth of lettuce and pepper. The optimal extracts displayed the highest diversity of secondary metabolites, and the highest total phenolics and flavonoids content. Through TLC and HPLC analysis the significantly lower phenolic content in the hot temperature treated samples was confirmed. A wide range of metabolites were detected in the DCM extracts through GC-MS analyses. The phytotoxicity of both the MW and DCM extracts were demonstrated, as germination and growth of pepper and lettuce were significantly inhibited, indicating the presence of more than one allelochemical compound which may affect the allelopathic activity of A. cruentus during changes in environmental temperatures.

Slovenian. Rastline zrnatega ščira so bile za namene te raziskave gojene v nadzorovanih optimalnih temperaturnih razmerah tri mesece (28/21 °C) in nato izpostavljene hladu (14/7 °C) in vročini (33/40 °C). Preučevan je bil vpliv temperaturnih režimov na profil metabolitov v listih ščira z metodami kot so TLC, HPLC in GC-MS spektroskopija. Fitotoksični potencial metanolno-vodnih (MW) in diklormetanskih (DCM) izvlečkov nadzemnih delov ščira je bil analizirana preko in vitro analize kalitve vrtne solate in paprike. Optimalni izvlečki so imeli največjo raznolikost sekundarnih metabolitov in največjo vsebnost celokupnih fenolov in flavonoidov. S TLC in HPLC analizo je bila potrjena značilno manjša vsebnost fenolov v vročinsko obdelanih vzorcih. Z GC-MS analizo je bil ugotovljen širok nabor metabolitov v diklormetanskih izvlečkih (DCM). Fitotoksičnost MW in DCM izvlečkov se je izrazila v značilno zmanjšani kalitvi in rasti solate in paprike, kar kaže na prisotnost več kot ene alelokemične spojine. To lahko posledično vpliva na alelopatsko aktivnost zrnatega ščira med spremembami temperature v okolju.