caa a22 4500 397522002 CHVBK 20180308164635.0 cr unu---uuuuu 161202e199511 xx s 000 0 eng 10.1093/jxb/46.11.1721 doi (NATIONALLICENCE)oxford-10.1093/jxb/46.11.1721 Modelling of quinolizidine alkaloid net flows in Lupinus albus and between L. albus and the parasite Cuscuta reflexa: new insights into the site of quinolizidine alkaloid synthesis [Elektronische Daten] [Pia Bäumel, W. Dieter Jeschke, Nicola Räth, Franz-Christian Czygan, Peter Proksch] The present work reveals new and completely different conclusions about the alkaloid economy of symbiotically fed Lupinus albus and L. albus parasitized by Cuscuta reflexa in the study period of 43-55 d after sowing of lupin. Net flows of alkaloids within lupin and between host and parasite were calculated using the molar ratio of alkaloid nitrogen: total nitrogen combined with known net flows of nitrogen in the transport fluids and analysing alkaloid accumulation in plant organs by HRGC. In contrast to previous studies, quinolizidine alkaloids were predicted to be synthesized mainly in the root of L. albus and to be predominantly transported via xylem to the apical plant shoot organs. Parasitism by C. reflexa for 12 d induced a decline of alkaloid content in the host L. albus up to 53% compared to control plants and alkaloid synthesis was halved—apparently due to a shortage of the precursor lysine. In spite of an additional decrease in nitrogen levels at the second harvest, the host-parasite system showed a1.3-fold higher alkaloid content than the control plants, 63% of the total alkaloids being attracted by Cuscuta. This indicates (a) restriction of catabolic processes within infected lupins, (b) a massive shift of nitrogen metabolism in the direction of alkaloids and (c) an enormous sink potential of Cuscuta for nitrogenous compounds. Although xylem was found to be the main translocation system for alkaloids, the modelling of alkaloid flows predicts Cuscuta to derive only 4.5% of its total alkaloid supply from the xylem and 95.5% from the phloem. By analogy with nitrogen flows, this finding requires xylemphloem transfers which were assumed to occur within the stem axis of lupin. A similar proportion regarding the contribution of xylem and phloem to the supply of Cuscuta was obtained for the net flows of two selected alkaloids, lupanine and 13α-tigloyloxylupanine, and for the import of total nitrogen. This result points to similar uptake mechanisms for alkaloid nitrogen and other nitrogenous compounds excluding discrimination of otherwise toxic alkaloids. Cuscuta is likely to overcome the chemical barrier of alkaloids by accumulation and catabolic processes. © Oxford University Press RESEARCH PAPERS nationallicence Cuscuta reflexa nationallicence Lupinus albus nationallicence parasitism nationallicence quinolizidine alkaloids nationallicence transport nationallicence Bäumel Pia Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut Jeschke W. Dieter Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Botanik I, Universität Würzburg Mittlerer Dallenbergweg 64, D-97082 Würzburg, Germany aut Räth Nicola Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut Czygan Franz-Christian Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut Proksch Peter Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut Journal of Experimental Botany Oxford University Press 46/11(1995-11), 1721-1730 0022-0957 46:11<1721 1995 46 exbotj https://doi.org/10.1093/jxb/46.11.1721 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1093/jxb/46.11.1721 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bäumel Pia Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut NATIONALLICENCE 700 1- Jeschke W. Dieter Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Botanik I, Universität Würzburg Mittlerer Dallenbergweg 64, D-97082 Würzburg, Germany aut NATIONALLICENCE 700 1- Räth Nicola Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut NATIONALLICENCE 700 1- Czygan Franz-Christian Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut NATIONALLICENCE 700 1- Proksch Peter Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl für Pharmazeutische Biologie, Universität Würzburg Mittlerer Dallenbergweg 64, D-97028 Würzburg, Germany aut NATIONALLICENCE 773 0- Journal of Experimental Botany Oxford University Press 46/11(1995-11), 1721-1730 0022-0957 46:11<1721 1995 46 exbotj Metadata rights reserved CC BY-NC-4.0 http://creativecommons.org/licenses/by-nc/4.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-oxford