Abstract
The involvement of the xanthophyll cycle in photoprotection of N-deficient spinach (Spinacia oleracea L. cv Nobel) was investigated. Spinach plants were fertilized with 14 mM nitrate (control, high N) versus 0.5 mM (low N) fertilizer, and grown under both high- and low-light conditions. Plants were characterized from measurements of photosynthetic oxygen exchange and chlorophyll fluorescence, as well as carotenoid and cholorophyll analysis. Compared with the high-N plants, the low-N plants showed a lower capacity for photosynthesis and a lower chlorophyll content, as well as a lower rate of photosystem II photosynthetic electron transport and a corresponding increase in thermal energy dissipation activity measured as nonphotochemical fluorescence quenching. The low-N plants displayed a greater fraction of the total xanthophyll cycle pool as zeaxanthin and antheraxanthin at midday, and an increase in the ratio of xanthophyll cycle pigments to total chlorophyll. These results indicate that under N limitation both the light-collecting system and the photosynthetic rate decrease. However, the increased dissipation of excess energy shows that there is excess light absorbed at midday. We conclude that spinach responds to N limitation by a combination of decreased light collection and increased thermal dissipation involving the xanthophyll cycle.
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Claims 3
Claim · model-written summary
Low nitrogen lowered photosynthetic capacity and chlorophyll content.
- Taxon
- Spinach
Spinacia oleraceat0 - Treatment
- low-Ne0
- Outcome
- capacity for photosynthesis and a lower chlorophyll contente0
- Direction
- lowere0
- Comparator
- high-Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared with the high-N plants, the low-N plants showed a lower capacity for photosynthesis and a lower chlorophyll content”
t0“Spinach”
Claim · model-written summary
Low nitrogen reduced photosystem II electron transport and increased thermal dissipation.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- low-Ne1
- Outcome
- photosystem II photosynthetic electron transporte0
- Direction
- lowere0
- Comparator
- high-Ne2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a lower rate of photosystem II photosynthetic electron transport and a corresponding increase in thermal energy dissipation activity”
e1“the low-N plants showed a lower capacity”
e2“Compared with the high-N plants”
t0“Spinach”
Claim · model-written summary
Low nitrogen increased zeaxanthin and antheraxanthin fraction and the xanthophyll to chlorophyll ratio.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- low-Ne0
- Outcome
- fraction of the total xanthophyll cycle pool as zeaxanthin and antheraxanthine0
- Direction
- greatere0
- Comparator
- high-Ne1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The low-N plants displayed a greater fraction of the total xanthophyll cycle pool as zeaxanthin and antheraxanthin at midday, and an increase in the ratio of xanthophyll cycle pigments to total chlorophyll”
e1“Compared with the high-N plants”
t0“Spinach”
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- no effect
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See all 24 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.