Abstract
C(4) photosynthesis is particularly successful at high light intensities and high temperatures, but is relatively rare when the average growing season temperature is less than about 15°C. We tested the hypothesis that rapidly reversible photoprotection enables some C(4) species to tolerate cool climates, by focusing on two questions: (1) Do chlorophyll fluorescence responses differ seasonally between co-occurring C(3) and C(4) grasses in the field? (2) Does xanthophyll-mediated photoprotection differ between the two pathways? Spartina pectinata (C(4) ) and Calamogrostis canadensis (C(3) ) were sampled in a herbaceous fresh-water meadow in New Brunswick, Canada (45°N 66°W). Non-photochemical thermal energy dissipation (Φ(NPQ) ) and the epoxidation state of the xanthophyll cycle (EPS) were used as indicators of photoprotection. We observed no differential susceptibility to chronic photoinhibition (i.e. photodamage) between the C(3) and C(4) species, except potentially during spring emergence. On average, C. canadensis showed higher levels of protective dynamic photoinhibition throughout the growing season, but S. pectinata had greater Φ(NPQ) and lower EPS during seasonal and daily temperature minima. The low Rubisco capacity of C(4) species is a potential limiting factor to C(4) success at high latitudes, but our findings suggest that it is unlikely via a photoinhibitory feedback mechanism.
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Claims 5
Claim · model-written summary
The two grasses had similar chronic photoinhibition susceptibility, except possibly at spring emergence.
- Taxon
- Spartina pectinata
Sporobolus michauxianuse1 - Outcome
- susceptibility to chronic photoinhibitione0
- Direction
- no differentiale0
- Qualifier
- except potentially during spring emergencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no differential susceptibility to chronic photoinhibition (i.e. photodamage) between the C(3) and C(4) species, except potentially during spring emergence”
t0“grasses”
e1“Spartina pectinata (C(4) ) and Calamogrostis canadensis (C(3) )”
Claim · model-written summary
C. canadensis had higher protective dynamic photoinhibition across the growing season.
Verbatim
e0“C. canadensis showed higher levels of protective dynamic photoinhibition throughout the growing season”
Claim · model-written summary
S. pectinata had greater Φ(NPQ) during temperature minima.
- Taxon
- S. pectinataSporobolus michauxianuse0
- Outcome
- Φ(NPQ)e0
- Direction
- greatere0
- Qualifier
- during seasonal and daily temperature minimae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“S. pectinata had greater Φ(NPQ) and lower EPS during seasonal and daily temperature minima”
Claim · model-written summary
S. pectinata had lower EPS during temperature minima.
- Taxon
- S. pectinataSporobolus michauxianuse0
- Outcome
- EPSe0
- Direction
- lowere0
- Qualifier
- during seasonal and daily temperature minimae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“S. pectinata had greater Φ(NPQ) and lower EPS during seasonal and daily temperature minima”
Claim · model-written summary
The authors judged photoinhibitory feedback unlikely to explain the Rubisco capacity limit at high latitudes.
- Taxon
- Spartina pectinataSporobolus michauxianuse1
- Outcome
- C(4) success at high latitudese0
- Qualifier
- it is unlikely via a photoinhibitory feedback mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The low Rubisco capacity of C(4) species is a potential limiting factor to C(4) success at high latitudes, but our findings suggest that it is unlikely via a photoinhibitory feedback mechanism”
t0“grasses”
e1“Spartina pectinata (C(4) ) and Calamogrostis canadensis (C(3) )”