Abstract
Nitrogen (N) is one of the major nutrients influencing photosynthesis and productivity of C4 plants as well as C3 plants. C4 photosynthesis operates through close coordination between mesophyll (M) and bundle sheath (BS) cells. However, how the development of structural and physiological traits in leaves of C4 plants is regulated under N limitation remains uncertain. We investigated structural and physiological responses of leaves of the NADP-ME-type C4 grass Sorghum bicolor to N limitation. Plants were grown under four levels of N supply (.05 to .6 g N per 5-L pot). Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance, leaf N and chlorophyll contents, and the activity ratio of phosphoenolpyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenase and increases in δ13C values and photosynthetic N use efficiency. Low-N leaves were thinner and had smaller photosynthetic cells, especially in M, resulting in lower M/BS tissue area ratio, and contained smaller and fewer chloroplasts. The BS chloroplasts in the low-N leaves accumulated abundant starch grains. The number of thylakoids per granal stack was reduced in M chloroplasts but not in BS chloroplasts. The low-N leaves had thicker cell walls, especially in the BS cells, which might be associated with less negative δ13C values, and fewer plasmodesmata in the BS cells. These data reveal structural and physiological responses of C4 plants to N limitation, most of which would be related to cellular N allocation, light use, CO2 diffusion and leakiness, and metabolite transport under N limitation.
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Claims 11
Claim · model-written summary
Lower nitrogen supply reduced net photosynthesis and stomatal conductance.
- Taxon
- Sorghum bicolor
Sorghum bicolort0 - Treatment
- Decreasing N supplye0
- Outcome
- net photosynthetic rate, stomatal conductancee0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance”
t0“Sorghum bicolor”
Claim · model-written summary
Lower nitrogen supply reduced leaf nitrogen and chlorophyll contents.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- Decreasing N supplye0
- Outcome
- leaf N and chlorophyll contentse0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance, leaf N and chlorophyll contents”
t0“Sorghum bicolor”
Claim · model-written summary
Lower nitrogen supply reduced the PEPC to Rubisco activity ratio.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- Decreasing N supplye0
- Outcome
- activity ratio of phosphoenolpyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenasee0
- Direction
- decreasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreasing N supply resulted in decreases in net photosynthetic rate, stomatal conductance, leaf N and chlorophyll contents, and the activity ratio of phosphoenolpyruvate carboxylase to ribulose 1,5-bisphosphate carboxylase/oxygenase”
t0“Sorghum bicolor”
Claim · model-written summary
Lower nitrogen supply increased δ13C values and photosynthetic nitrogen use efficiency.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- Decreasing N supplye1
- Outcome
- δ13C values and photosynthetic N use efficiencye0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increases in δ13C values and photosynthetic N use efficiency”
e1“Decreasing N supply resulted in decreases in net photosynthetic rate”
t0“Sorghum bicolor”
Claim · model-written summary
Low-nitrogen leaves were thinner with smaller photosynthetic cells, particularly mesophyll cells, and a lower mesophyll to bundle sheath area ratio.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- Low-Ne0
- Outcome
- M/BS tissue area ratioe0
- Direction
- lowere0
- Qualifier
- thinner and had smaller photosynthetic cells, especially in Me0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low-N leaves were thinner and had smaller photosynthetic cells, especially in M, resulting in lower M/BS tissue area ratio”
t0“Sorghum bicolor”
Claim · model-written summary
Low-nitrogen leaves had smaller and fewer chloroplasts.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- Low-Ne0
- Outcome
- chloroplastse0
- Direction
- smaller and fewere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low-N leaves were thinner and had smaller photosynthetic cells, especially in M, resulting in lower M/BS tissue area ratio, and contained smaller and fewer chloroplasts”
t0“Sorghum bicolor”
Claim · model-written summary
Bundle sheath chloroplasts in low-nitrogen leaves accumulated abundant starch grains.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Organ / stage
- BS chloroplastse0
- Outcome
- accumulated abundant starch grainse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The BS chloroplasts in the low-N leaves accumulated abundant starch grains”
t0“Sorghum bicolor”
Claim · model-written summary
Low nitrogen reduced thylakoids per granal stack in mesophyll, but not bundle sheath, chloroplasts.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Organ / stage
- M chloroplastse0
- Treatment
- Low-Ne1
- Outcome
- number of thylakoids per granal stacke0
- Direction
- reducede0
- Comparator
- BS chloroplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The number of thylakoids per granal stack was reduced in M chloroplasts but not in BS chloroplasts”
e1“Low-N leaves had thicker cell walls”
t0“Sorghum bicolor”
Claim · model-written summary
Low-nitrogen leaves had thicker cell walls, particularly in bundle sheath cells.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Organ / stage
- BS cellse0
- Treatment
- low-Ne0
- Outcome
- cell wallse0
- Direction
- thickere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The low-N leaves had thicker cell walls, especially in the BS cells”
t0“Sorghum bicolor”
Claim · model-written summary
Low-nitrogen leaves had fewer plasmodesmata in bundle sheath cells.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Treatment
- low-Ne0
- Outcome
- plasmodesmata in the BS cellse0
- Direction
- fewere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The low-N leaves had thicker cell walls, especially in the BS cells, which might be associated with less negative δ13C values, and fewer plasmodesmata in the BS cells”
t0“Sorghum bicolor”
Claim · model-written summary
The authors suggest thicker bundle sheath cell walls may be associated with less negative δ13C values.
- Taxon
- Sorghum bicolorSorghum bicolort0
- Organ / stage
- BS cellse0
- Outcome
- δ13C valuese0
- Direction
- less negativee0
- Qualifier
- might be associatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thicker cell walls, especially in the BS cells, which might be associated with less negative δ13C values”
t0“Sorghum bicolor”
The same questions in other papers
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This paper is about lacking the nutrient, so it counts the other way round here.
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This paper is about lacking the nutrient, so it counts the other way round here.
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See all 5 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.