Abstract
The partitioning of carbon for growth, storage and constitutive chemical defenses is widely framed in terms of a hypothetical sink-source differential that varies with nutrient supply. According to this framework, phenolics accrual is passive and occurs in source leaves when normal sink growth is not sustainable due to a nutrient limitation. In assessing this framework, we present gene and metabolite evidence that condensed tannin (CT) accrual is strongest in sink leaves and sequesters carbon in a way that impinges upon foliar sink strength and upon phenolic glycoside (PG) accrual in Populus. The work was based on two Populus fremontii × angustifolia backcross lines with contrasting rates of CT accrual and growth, and equally large foliar PG reserves. However, foliar PG accrual was developmentally delayed in the high-CT, slow-growth line (SG), and nitrogen-limitation led to increased foliar PG accrual only in the low-CT, fast-growth line (FG). Metabolite profiling of developing leaves indicated comparatively carbon-limited amino acid metabolism, depletion of several Krebs cycle intermediates and reduced organ sink strength in SG. Gene profiling indicated that CT synthesis decreased as leaves expanded and PGs increased. A most striking finding was that the nitrogenous monoamine phenylethylamine accumulated only in leaves of SG plants. The potential negative impact of CT hyper-accumulation on foliar sink strength, as well as a mechanism for phenylethylamine involvement in CT polymerization in Populus are discussed. Starch accrual in source leaves and CT accrual in sink leaves of SG may both contribute to the maintenance of a slow-growth phenotype suited to survival in nutrient-poor habitats.
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Claims 12
Claim · model-written summary
Condensed tannin accrual was strongest in sink leaves of Populus.
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“condensed tannin (CT) accrual is strongest in sink leaves and sequesters carbon in a way that impinges upon foliar sink strength and upon phenolic glycoside (PG) accrual in Populus.”
Claim · model-written summary
CT carbon sequestration impinged on foliar sink strength.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sequesters carbon in a way that impinges upon foliar sink strength”
t0“Populus”
Claim · model-written summary
CT carbon sequestration impinged on phenolic glycoside accrual.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“sequesters carbon in a way that impinges upon foliar sink strength and upon phenolic glycoside (PG) accrual in Populus.”
Claim · model-written summary
Foliar PG accrual was delayed in the high-CT slow-growth line.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“foliar PG accrual was developmentally delayed in the high-CT, slow-growth line (SG)”
t0“Populus”
Claim · model-written summary
Nitrogen limitation increased PG accrual only in the low-CT fast-growth line.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrogen-limitation led to increased foliar PG accrual only in the low-CT, fast-growth line (FG).”
t0“Populus”
Claim · model-written summary
The slow-growth line had comparatively carbon-limited amino acid metabolism.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“comparatively carbon-limited amino acid metabolism, depletion of several Krebs cycle intermediates and reduced organ sink strength in SG.”
t0“Populus”
Claim · model-written summary
The slow-growth line had depletion of several Krebs cycle intermediates.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“depletion of several Krebs cycle intermediates and reduced organ sink strength in SG.”
t0“Populus”
Claim · model-written summary
The slow-growth line had reduced organ sink strength.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced organ sink strength in SG.”
t0“Populus”
Claim · model-written summary
CT synthesis decreased as leaves expanded.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CT synthesis decreased as leaves expanded”
t0“Populus”
Claim · model-written summary
Phenolic glycosides increased as leaves expanded.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“as leaves expanded and PGs increased.”
t0“Populus”
Claim · model-written summary
Phenylethylamine accumulated only in slow-growth line leaves.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phenylethylamine accumulated only in leaves of SG plants.”
t0“Populus”
Claim · model-written summary
The authors suggest starch and CT accrual may maintain the slow-growth phenotype in nutrient-poor habitats.
- Material
- SGe0
- Outcome
- slow-growth phenotypee0
- Qualifier
- Starch accrual in source leaves and CT accrual in sink leavese0
- Setting
- nutrient-poor habitatse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Starch accrual in source leaves and CT accrual in sink leaves of SG may both contribute to the maintenance of a slow-growth phenotype suited to survival in nutrient-poor habitats.”
t0“Populus”
The same questions in other papers
nitrogen · quality: phytochemicals · Populus (poplar)Results agree
1 paper in the same direction as this paper
This paper is about lacking the nutrient, so it counts the other way round here.
- negative
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.