Abstract
Cellular oxalate, widely distributed in many plants, is implicated to play important roles in various functions and is also known to affect food qualities adversely in fruits and vegetables. How oxalate is regulated in plants is currently not well understood. Glycolate oxidase (GLO) has long been considered as an important player in oxalate accumulation in plants. To gain further insight into the biochemical and molecular mechanisms, the possible roles of GLO in the process were studied. Drastically different levels of oxalate could be achieved by treating rice with various nitrogen forms (nitrate versus ammonium). While nitrate stimulated oxalate accumulation, ammonium reduced its level. Such treatments resulted in similar pattern changes for some other related organic acids, such as glycolate, oxaloacetate, and malate. By feeding plants with exogenous glycolate it was possible almost completely to restore the ammonium-decreased oxalate level. Under the two treatments few differences were observed for GLO mRNA levels, protein levels, and in vitro activities. Both K(m) for glycolate/glyoxylate and K(i) for oxalate remained almost the same for GLO purified from either nitrate- or ammonium-fed leaves. A further in vivo study, with transgenic plants carrying an estradiol-inducible GLO antisense gene, showed that, while the estradiol-induced antisense expression remarkably reduced both GLO protein levels and activities, oxalate levels were not significantly altered in the estradiol-treated transgenic plants. Taken together, it is suggested that oxalate accumulation and regulation is independent of GLO in rice leaves.
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Claims 9
Claim · model-written summary
Nitrate stimulated oxalate accumulation in rice.
- Taxon
- rice
Oryza sativat0 - Organ / stage
- leavest0
- Treatment
- nitratee0
- Outcome
- oxalate accumulatione0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While nitrate stimulated oxalate accumulation, ammonium reduced its level.”
t0“rice leaves”
Claim · model-written summary
Ammonium reduced oxalate level in rice.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“While nitrate stimulated oxalate accumulation, ammonium reduced its level.”
t0“rice leaves”
Claim · model-written summary
Nitrogen treatments changed glycolate, oxaloacetate and malate in a similar pattern.
- Taxon
- riceOryza sativat0
- Treatment
- Such treatmentse0
- Outcome
- glycolate, oxaloacetate, and malatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such treatments resulted in similar pattern changes for some other related organic acids, such as glycolate, oxaloacetate, and malate.”
t0“rice leaves”
Claim · model-written summary
Exogenous glycolate almost completely restored the oxalate level decreased by ammonium.
- Taxon
- riceOryza sativat0
- Treatment
- exogenous glycolatee0
- Outcome
- oxalate levele0
- Direction
- restoree0
- Qualifier
- almost completelye0
- Comparator
- ammonium-decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By feeding plants with exogenous glycolate it was possible almost completely to restore the ammonium-decreased oxalate level.”
t0“rice leaves”
Claim · model-written summary
GLO mRNA, protein and in vitro activity differed little between nitrogen treatments.
- Taxon
- riceOryza sativat0
- Treatment
- two treatmentse0
- Gene
- GLOe0
- Outcome
- GLO mRNA levels, protein levels, and in vitro activitiese0
- Direction
- few differencese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under the two treatments few differences were observed for GLO mRNA levels, protein levels, and in vitro activities.”
t0“rice leaves”
Claim · model-written summary
GLO kinetic constants for glycolate, glyoxylate and oxalate remained almost the same under nitrate and ammonium feeding.
- Taxon
- riceOryza sativat0
- Treatment
- nitrate- or ammonium-fede0
- Gene
- GLOe0
- Outcome
- K(m) for glycolate/glyoxylate and K(i) for oxalatee0
- Direction
- remained almost the samee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both K(m) for glycolate/glyoxylate and K(i) for oxalate remained almost the same for GLO purified from either nitrate- or ammonium-fed leaves.”
t0“rice leaves”
Claim · model-written summary
Estradiol induced GLO antisense expression reduced GLO protein levels and activities.
- Taxon
- riceOryza sativat0
- Treatment
- estradiol-induced antisense expressione0
- Gene
- GLOe0
- Outcome
- GLO protein levels and activitiese0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the estradiol-induced antisense expression remarkably reduced both GLO protein levels and activities”
t0“rice leaves”
Claim · model-written summary
Estradiol treatment did not significantly alter oxalate levels in transgenic rice.
- Taxon
- riceOryza sativat0
- Material
- transgenic plantse0
- Treatment
- estradiol-treatede0
- Outcome
- oxalate levelse0
- Direction
- not significantly alterede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“oxalate levels were not significantly altered in the estradiol-treated transgenic plants.”
t0“rice leaves”
Claim · model-written summary
The authors suggest oxalate accumulation and regulation is independent of GLO in rice leaves.
- Taxon
- riceOryza sativae0
- Organ / stage
- leavese0
- Gene
- GLOe0
- Outcome
- oxalate accumulation and regulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it is suggested that oxalate accumulation and regulation is independent of GLO in rice leaves.”
The same questions in other papers
glycolate · molecular: metabolites · Oryza sativa (rice)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
nitrogen · molecular: metabolites · Oryza sativa (rice)Positive and negative results
85 papers in the same direction as this paper · 34 in the opposite direction · 1 reporting no difference from an alternative
- negative
- negative
- negative
117 papers more in this group
See all 121 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.