Abstract
ABSTRACT Ricinus communis L. was grown under limiting N supply in quartz sand culture, fed with 0.2, 1 or 5 mol m −3 NO 3 − , or in liquid culture with 0.022, 0.05 or 0.5 mol m −3 NO 3 − . Some of the plants were infected with Cuscuta reflexa Roxb. As occurred for the host, dry matter production and growth of C. reflexa were severely depressed with decreasing N supply to the host. When parasitized by C. reflexa , the shoot and root dry weight of Ricinus was diminished at all levels of N nutrition, but the total dry weight of host plus parasite was almost the same as that of uninfected Ricinus. In contrast to the situation in Lupinus albus (Jeschke et al. 1994b), infection by Cuscuta resulted in increased tissue N levels in the host and the N content of the system Ricinus plus C. reflexa was the same or even somewhat larger than that of uninfected plants. This indicated a sink‐dependent stimulation of nitrate uptake. As a result of decreased root weights, nitrate uptake g −1 FW was stimulated by 80, 60 or only 40% at 0.2, 1 or 5 mol m −3 nitrate supply. Increased nitrate uptake was reflected, particularly at low N supply, in xylem transport; xylem sap nitrate concentrations were substantially elevated, while those of amino acids were decreased in parasitized plants. This indicated an inhibition of nitrate assimilation in roots of parasitized plants under limiting N supply. Besides these effects on N relations, C. reflexa induced a substantial sink‐dependent stimulation of net photosynthesis in host leaves and a concomitant increase in stomatal opening and transpiration. This stimulation depended on the relative sink size induced by Cuscuta , on nitrogen nutrition and on leaf age, indicating that delayed senescence of leaves contributes to the overall effects of Cuscuta on its host. The Cuscuta ‐induced inhibition of nitrate assimilation in the roots and the increase in nitrate uptake suggest that nitrate reduction was shifted towards the leaves in the presence of C. reflexa. The stimulating effects of C. reflexa in the Ricinus‐Cuscuta association are compared with the strongly inhibitory effects occurring in the tripartite association L. albus–Rhizobium–Cuscuta reflexa.
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Claims 14
Claim · model-written summary
Lower host nitrogen supply depressed parasite growth and dry matter production.
- Taxon
- Ricinus communis
Ricinus communist0 - Treatment
- decreasing N supplye0
- Interactor
- C. reflexa
Cuscuta reflexae0parasite - Outcome
- dry matter production and growth of C. reflexae0
- Direction
- depressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dry matter production and growth of C. reflexa were severely depressed with decreasing N supply to the host”
t0“Ricinus communis”
Claim · model-written summary
Parasitism diminished Ricinus shoot and root dry weight at every nitrogen level.
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- shoot and root dry weight of Ricinuse0
- Direction
- diminishede0
RicinusNot reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the shoot and root dry weight of Ricinus was diminished at all levels of N nutrition”
t0“Cuscuta reflexa”
Claim · model-written summary
Combined host and parasite dry weight was nearly equal to uninfected Ricinus dry weight.
- Treatment
- host plus parasitee0
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- total dry weighte0
- Direction
- almost the samee0
- Comparator
- uninfected Ricinuse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total dry weight of host plus parasite was almost the same as that of uninfected Ricinus”
t0“Cuscuta reflexa”
Claim · model-written summary
Cuscuta infection raised tissue nitrogen levels in Ricinus.
- Taxon
- Ricinus communisRicinus communist0
- Treatment
- infection by Cuscutae0
- Outcome
- tissue N levelse0
- Direction
- increasede0
.jpg?width=60){kind=small}
CuscutaNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“infection by Cuscuta resulted in increased tissue N levels in the host”
t0“Ricinus communis”
Claim · model-written summary
Total nitrogen of the Ricinus–Cuscuta system was equal to or greater than that of uninfected plants.
- Treatment
- Ricinus plus C. reflexae0
- Interactor
- C. reflexaCuscuta reflexae0parasite
- Outcome
- N content of the system Ricinus plus C. reflexae0
- Direction
- the same or even somewhat largere0
- Comparator
- uninfected plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the N content of the system Ricinus plus C. reflexa was the same or even somewhat larger than that of uninfected plants”
Claim · model-written summary
Parasitism increased nitrate uptake per gram fresh root weight by 80% at 0.2 mol m−3 nitrate supply.
- Taxon
- Ricinus communisRicinus communist1
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- nitrate uptake g −1 FWe0
- Direction
- stimulatede0
- Value
- 80e0
- Qualifier
- 0.2e0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate uptake g −1 FW was stimulated by 80, 60 or only 40% at 0.2, 1 or 5 mol m −3 nitrate supply”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Parasitism increased nitrate uptake per gram fresh root weight by 60% at 1 mol m−3 nitrate supply.
- Taxon
- Ricinus communisRicinus communist1
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- nitrate uptake g −1 FWe0
- Direction
- stimulatede0
- Value
- 60e0
- Qualifier
- 1 or 5 mol m −3 nitrate supplye0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate uptake g −1 FW was stimulated by 80, 60 or only 40% at 0.2, 1 or 5 mol m −3 nitrate supply”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Parasitism increased nitrate uptake per gram fresh root weight by 40% at 5 mol m−3 nitrate supply.
- Taxon
- Ricinus communisRicinus communist1
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- nitrate uptake g −1 FWe0
- Direction
- stimulatede0
- Value
- 40%e0
- Qualifier
- 5 mol m −3 nitrate supplye0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate uptake g −1 FW was stimulated by 80, 60 or only 40% at 0.2, 1 or 5 mol m −3 nitrate supply”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Xylem sap nitrate concentration rose in parasitized Ricinus.
- Taxon
- Ricinus communisRicinus communist1
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- xylem sap nitrate concentrationse0
- Direction
- elevatede0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“xylem sap nitrate concentrations were substantially elevated”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Xylem sap amino acid concentrations fell in parasitized plants.
- Taxon
- Ricinus communisRicinus communist1
- Treatment
- parasitized plantse0
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- amino acidse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“those of amino acids were decreased in parasitized plants”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Cuscuta stimulated net photosynthesis in host leaves.
- Taxon
- Ricinus communisRicinus communist0
- Treatment
- C. reflexae0
- Interactor
- C. reflexaCuscuta reflexae0parasite
- Outcome
- net photosynthesis in host leavese0
- Direction
- stimulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“C. reflexa induced a substantial sink‐dependent stimulation of net photosynthesis in host leaves”
t0“Ricinus communis”
Claim · model-written summary
Cuscuta increased stomatal opening and transpiration in host leaves.
- Taxon
- Ricinus communisRicinus communist1
- Interactor
- Cuscuta reflexaCuscuta reflexat0parasite
- Outcome
- stomatal opening and transpiratione0
- Direction
- increasee0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a concomitant increase in stomatal opening and transpiration”
t0“Cuscuta reflexa”
t1“Ricinus communis”
Claim · model-written summary
Photosynthetic stimulation depended on parasite sink size, nitrogen nutrition and leaf age.
- Taxon
- Ricinus communisRicinus communist0
- Outcome
- This stimulatione0
- Qualifier
- relative sink size induced by Cuscuta , on nitrogen nutrition and on leaf agee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This stimulation depended on the relative sink size induced by Cuscuta , on nitrogen nutrition and on leaf age”
t0“Ricinus communis”
Claim · model-written summary
The authors infer that Cuscuta shifts nitrate reduction toward leaves.
- Taxon
- Ricinus communisRicinus communist0
- Interactor
- C. reflexaCuscuta reflexae0parasite
- Outcome
- nitrate reduction was shifted towards the leavese0
- Direction
- shifted towards the leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggest that nitrate reduction was shifted towards the leaves in the presence of C. reflexa”
t0“Ricinus communis”