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Solute fluxes from tobacco to the parasitic angiosperm Orobanche cernua and the influence of infection on host carbon and nitrogen relations
Author(s) -
Hibberd J. M.,
Quick W. P.,
Press M. C.,
Scholes J. D.,
Jeschke W. D.
Publication year - 1999
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1999.00462.x
Subject(s) - orobanche , xylem , phloem , parasitic plant , biology , botany , orobanchaceae , host (biology) , parasite hosting , carbon fibers , nitrogen , chemistry , ecology , germination , materials science , world wide web , computer science , composite number , composite material , organic chemistry
Orobanche species are holoparasites which are very efficient sinks for host‐derived solutes. Here, we report the use of direct measurements of xylem sap solute concentrations and water fluxes, together with a modelling procedure to calculate element fluxes within an association between Orobanche cernua and its tobacco host. Infection of tobacco by the parasite markedly influenced carbon acquisition and partitioning; net fixation of carbon was 20% higher in infected tobacco compared with controls. Orobanche cernua caused a 84% increase in net carbon flux moving downward from the tobacco shoot and 73% of this carbon was intercepted by the parasite, almost entirely through the phloem (>99%). Further, the parasite also exerted a large impact on the nitrogen relations of the plant, notably nitrate uptake was stimulated and the amino acid content of xylem sap was lower. The parasite also relied heavily on host phloem for the supply of other resources, with only 5 to 15% of N, and 16% of K, 23% of Na, 63% of Mg and 13% of S being derived from the xylem. Thus, we provide quantitative information on the phloem dependency of the parasite and show that host carbon and nitrogen metabolism is stimulated as a consequence of infection.