Abstract
BACKGROUND: myo-Inositol (Ins) metabolism during early stages of seed development plays an important role in determining the distributional relationships of some seed storage components such as the antinutritional factors, sucrose galactosides (also known as raffinose oligosaccharides) and phytic acid (PhA) (myo-inositol 1,2,3,4,5,6-hexakisphosphate). The former is a group of oligosaccharides, which plays a role in desiccation at seed maturation. They are not easily digested by monogastric animals, hence their flatulence-causing properties. Phytic acid is highly negatively charged, which chelates positive ions of essential minerals and decreases their bioavailability. It is also a major cause of phosphate-related water pollution. Our aim was to investigate the influence of competitive diversion of Ins as common substrate on the biosynthesis of phytate and sucrose galactosides. RESULTS: We have studied the initial metabolic patterns of Ins in developing seeds of Brassica napus and determined that early stages of seed development are marked by rapid deployment of Ins into a variety of pathways, dominated by interconversion of polar (Ins phosphates) and non-polar (phospholipids) species. In a time course experiment at early stages of seed development, we show Ins to be a highly significant constituent of the endosperm and seed coat, but with no phytate biosynthesis occurring in either tissue. Phytate accumulation appears to be confined mainly within the embryo throughout seed development and maturation. In our approach, the gene for myo-inositol methyltransferase (IMT), isolated from Mesembryanthemum crystallinum (ice plant), was transferred to B. napus under the control of the seed-specific promoters, napin and phaseolin. Introduction of this new metabolic step during seed development prompted Ins conversion to the corresponding monomethyl ether, ononitol, and affected phytate accumulation. We were able to produce homozygous transgenic lines with 19%-35% average phytate reduction. Additionally, changes in the raffinose content and related sugars occurred along with enhanced sucrose levels. Germination rates, viability and other seed parameters were unaffected by the IMT transgene over-expression. CONCLUSIONS: Competitive methylation of Ins during seed development reduces seed antinutritional components and enhances its nutritional characteristics while maintaining adequate phosphate reserves. Such approach should potentially raise the canola market value and likely, that of other crops.
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Claims 9
Claim · model-written summary
Early Brassica napus seed development rapidly channels inositol among pathways dominated by polar and nonpolar species.
- Taxon
- Brassica napus
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse1 - Organ / stage
- early stages of seed developmente0
- Outcome
- rapid deployment of Ins into a variety of pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“early stages of seed development are marked by rapid deployment of Ins into a variety of pathways, dominated by interconversion of polar (Ins phosphates) and non-polar (phospholipids) species”
e1“developing seeds of Brassica napus”
Claim · model-written summary
Inositol was a highly significant constituent of endosperm and seed coat.
- Taxon
- Brassica napusBrassica napuse1
- Organ / stage
- endosperm and seed coate0
- Outcome
- Ins to be a highly significant constituente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ins to be a highly significant constituent of the endosperm and seed coat”
e1“developing seeds of Brassica napus”
Claim · model-written summary
No phytate biosynthesis occurred in endosperm or seed coat.
- Taxon
- Brassica napusBrassica napuse2
- Organ / stage
- endosperm and seed coate1
- Outcome
- no phytate biosynthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no phytate biosynthesis occurring in either tissue”
e1“endosperm and seed coat”
e2“developing seeds of Brassica napus”
Claim · model-written summary
Phytate accumulated mainly in the embryo throughout development and maturation.
- Taxon
- Brassica napusBrassica napuse1
- Organ / stage
- embryoe0
- Outcome
- Phytate accumulatione0
- Qualifier
- throughout seed development and maturatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phytate accumulation appears to be confined mainly within the embryo throughout seed development and maturation”
e1“developing seeds of Brassica napus”
Claim · model-written summary
Seed-specific IMT expression converted inositol to ononitol.
- Taxon
- B. napusBrassica napuse1
- Treatment
- Introduction of this new metabolic stepe0
- Gene
- myo-inositol methyltransferase (IMT)e1
- Outcome
- Ins conversion to the corresponding monomethyl ether, ononitole0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Introduction of this new metabolic step during seed development prompted Ins conversion to the corresponding monomethyl ether, ononitol”
e1“the gene for myo-inositol methyltransferase (IMT), isolated from Mesembryanthemum crystallinum (ice plant), was transferred to B. napus”
Claim · model-written summary
IMT transgenic lines reduced average seed phytate by 19%-35%.
- Taxon
- Brassica napusBrassica napuse1
- Material
- homozygous transgenic linese0
- Treatment
- IMT transgene over-expressione2
- Outcome
- phytatee0
- Direction
- reductione0
- Value
- 19%-35%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“homozygous transgenic lines with 19%-35% average phytate reduction”
e1“developing seeds of Brassica napus”
e2“IMT transgene over-expression”
Claim · model-written summary
IMT expression changed raffinose and related sugar content.
- Taxon
- Brassica napusBrassica napuse2
- Treatment
- IMT transgene over-expressione1
- Outcome
- raffinose content and related sugarse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in the raffinose content and related sugars occurred”
e1“IMT transgene over-expression”
e2“developing seeds of Brassica napus”
Claim · model-written summary
IMT expression enhanced seed sucrose levels.
- Taxon
- Brassica napusBrassica napuse2
- Treatment
- IMT transgene over-expressione1
- Outcome
- sucrose levelse0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhanced sucrose levels”
e1“IMT transgene over-expression”
e2“developing seeds of Brassica napus”
Claim · model-written summary
IMT overexpression left germination, viability and other seed parameters unaffected.
- Taxon
- Brassica napusBrassica napuse1
- Treatment
- IMT transgene over-expressione0
- Outcome
- Germination rates, viability and other seed parameterse0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Germination rates, viability and other seed parameters were unaffected by the IMT transgene over-expression”
e1“developing seeds of Brassica napus”
The same questions in other papers
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- positive
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3 papers in the same direction as this paper
- positive
- positive
- positive
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.