Abstract
Boron is generally considered to be phloem immobile or to have only limited phloem mobility in higher plants. Evidence suggests, however, that B may be mobile in some species within the Pyrus, Malus and Prunus genera. These genera utilize sorbitol as a primary translocated photosynthate and it has been clearly demonstrated that B forms stable complexes with sorbitol in vitro. In the research presented here we demonstrate, further, that B is freely phloem mobile in Pyrus, Malus and Prunus species and suggest that this is mediated by the formation and transport of B-sorbitol complexes. The pattern of B distribution within shoot organs and the translocation of foliar-applied, isotopically-enriched 10 B was studied in six tree species. Results demonstrate that in species in which sorbitol is a major sugar (sorbitol-rich), B is freely mobile while in species that produce little or no sorbitol (sorbitol-poor) B is largely immobile. The sorbitol-rich species used here were almond [ Prunus amygdalus B. syn. P. dulcis (Mill.)], apple ( Malus domestica B.) and nectarine ( Prunus persica L. B. var. nectarina M.), sorbitol-poor species included fig ( Ficus carica L.), pistachio ( Pistacia vera L.) and walnut ( Juglans regia L.). In sorbitol-rich species foliar applied 10 B was transported from the treated leaves to adjacent fruit and specifically to the fruit tissues (hull, shell or kernel) that developed during the experimental period. Whereas, foliar-applied 10 B was rapidly translocated out of leaves, only a small percentage of the 11 B present in the leaf at the time of foliar application was retranslocated. In sorbitol-rich species, B concentrations differed only slightly between old and young leaves while fruit tissue had significantly greater B concentrations than leaves. In contrast, sorbitol-poor species had significantly higher B concentrations in older leaves than young leaves while fruit tissue had the lowest B concentration. This occurred irrespective the source of plant B (soil, solution or foliar-applied). In a subsequent experiment the growth of apple trees in solutions free of applied B was maintained solely by foliar applications of B to mature leaves. These results indicate that B is mobile in species that produce significant amounts of sorbitol. We propose that the mobility of B in these species is mediated by the formation of B-sorbitol complexes.
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Claims 12
Claim · model-written summary
Boron was freely phloem mobile in Pyrus.
PyrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B is freely phloem mobile in Pyrus, Malus and Prunus species”
t0“Sorbitol-rich Species”
Claim · model-written summary
Boron was freely phloem mobile in Malus.
- Outcome
- B is freely phloem mobilee0
MalusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B is freely phloem mobile in Pyrus, Malus and Prunus species”
Claim · model-written summary
Boron was freely phloem mobile in Prunus.
- Outcome
- B is freely phloem mobilee0
PrunusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“B is freely phloem mobile in Pyrus, Malus and Prunus species”
Claim · model-written summary
Boron was freely mobile in sorbitol-rich species but largely immobile in sorbitol-poor species.
Verbatim
e0“in species in which sorbitol is a major sugar (sorbitol-rich), B is freely mobile while in species that produce little or no sorbitol (sorbitol-poor) B is largely immobile.”
Claim · model-written summary
Foliar 10 B moved from treated leaves to adjacent developing fruit tissues in sorbitol-rich species.
Verbatim
e0“In sorbitol-rich species foliar applied 10 B was transported from the treated leaves to adjacent fruit and specifically to the fruit tissues (hull, shell or kernel) that developed during the experimental period.”
Claim · model-written summary
Foliar 10 B rapidly left leaves, whereas only a small share of preexisting 11 B was retranslocated.
Verbatim
e0“foliar-applied 10 B was rapidly translocated out of leaves, only a small percentage of the 11 B present in the leaf at the time of foliar application was retranslocated.”
t0“Sorbitol-rich Species”
Claim · model-written summary
Old and young leaves had only slightly different B concentrations in sorbitol-rich species.
Verbatim
e0“In sorbitol-rich species, B concentrations differed only slightly between old and young leaves”
Claim · model-written summary
Fruit B concentrations exceeded leaf concentrations significantly in sorbitol-rich species.
Verbatim
e0“fruit tissue had significantly greater B concentrations than leaves.”
t0“Sorbitol-rich Species”
Claim · model-written summary
Older leaves had significantly more B than young leaves in sorbitol-poor species.
Verbatim
e0“sorbitol-poor species had significantly higher B concentrations in older leaves than young leaves”
Claim · model-written summary
Fruit tissue had the lowest B concentration in sorbitol-poor species.
Verbatim
e0“fruit tissue had the lowest B concentration.”
t0“Sorbitol-rich Species”
Claim · model-written summary
Foliar B alone maintained apple growth in solutions without applied B.
- Taxon
- apple trees
Malus domesticae0 - Treatment
- foliar applications of B to mature leavese0
- Outcome
- growthe0
- Direction
- maintainede0
- Comparator
- solutions free of applied Be0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the growth of apple trees in solutions free of applied B was maintained solely by foliar applications of B to mature leaves.”
Claim · model-written summary
Authors proposed B-sorbitol complex formation and transport as the mechanism of B mobility.
Verbatim
e0“We propose that the mobility of B in these species is mediated by the formation of B-sorbitol complexes.”
The same questions in other papers
application · growth · Malus domestica (apple)Positive and negative results
75 papers in the same direction as this paper · 31 in the opposite direction
- no effect
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See all 107 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.