Abstract
Oat leaves produce phytoalexins, avenanthramides, in response to infection by pathogens or treatment with elicitors. The metabolism of avenanthramides was investigated using low molecular weight, partially deacetylated chitin as an elicitor. When oat leaf segments are floated on the elicitor solution, avenanthramides accumulate in the solution. The transfer of elicited oat leaves to solutions containing stable-isotope-labeled avenanthramides resulted in a rapid decrease in the labeled avenanthramides, suggesting the metabolism of avenanthramides. The rate of decrease was enhanced by elicitor treatment, and was dependent on the species of avenanthramides, with avenanthramide B decreasing most rapidly. The rates of biosynthesis and metabolism of avenanthramides A and B were measured using a model of isotope-labeling dynamics. Avenanthramide B was found to be more actively biosynthesized and metabolized than avenanthramide A. Radiolabeled avenanthramide B was incorporated into the cell wall fraction and 99% of incorporated activity was released by alkaline treatment. Gel filtration indicated that high-molecular-weight compounds derived from avenanthramide B were released by alkaline treatment. The decrease in stable-isotope-labeled avenanthramides was suppressed by catalase, salicylhydroxamic acid, and sodium ascorbate, suggesting the involvement of peroxidase in the metabolism. Consistent with this, peroxidase activity that accepts avenanthramide B as a substrate was induced in apoplastic fractions by elicitor treatment. The appearance of multiple basic isoperoxidases was observed by activity staining with 3-amino-9-ethylcarbazole coupled with isoelectric focusing of proteins from elicitor-treated leaves. These findings suggest that accumulated avenanthramides are further metabolized in apoplasts in oat leaves by inducible isoperoxidases.
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Claims 13
Claim · model-written summary
Avenanthramides accumulated in the solution when oat leaf segments were floated on the elicitor solution.
- Taxon
- Oat
Avena sativae0 - Treatment
- floated on the elicitor solutione1
- Outcome
- avenanthramides accumulate in the solutione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“When oat leaf segments are floated on the elicitor solution, avenanthramides accumulate in the solution”
Claim · model-written summary
Transfer of elicited oat leaves to solutions with stable-isotope-labeled avenanthramides caused a rapid decrease in the labeled avenanthramides.
- Taxon
- OatAvena sativae0
- Treatment
- solutions containing stable-isotope-labeled avenanthramidese2
- Outcome
- labeled avenanthramidese2
- Direction
- rapid decreasee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e2“The transfer of elicited oat leaves to solutions containing stable-isotope-labeled avenanthramides resulted in a rapid decrease in the labeled avenanthramides”
Claim · model-written summary
Elicitor treatment enhanced the rate of avenanthramide decrease in oat leaves.
- Taxon
- OatAvena sativae0
- Treatment
- elicitor treatmente3
- Outcome
- rate of decreasee3
- Direction
- enhancede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e3“The rate of decrease was enhanced by elicitor treatment”
Claim · model-written summary
The rate of avenanthramide decrease depended on the avenanthramide species, with avenanthramide B decreasing most rapidly.
- Taxon
- OatAvena sativae0
- Compound
- avenanthramide Be4
- Outcome
- rate of decreasee3
- Direction
- decreasing most rapidlye4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e3“The rate of decrease was enhanced by elicitor treatment”
e4“was dependent on the species of avenanthramides, with avenanthramide B decreasing most rapidly”
Claim · model-written summary
Avenanthramide B was biosynthesized and metabolized more actively than avenanthramide A.
- Taxon
- OatAvena sativae0
- Compound
- Avenanthramide Be5
- Outcome
- biosynthesized and metabolizede5
- Direction
- more activelye5
- Comparator
- avenanthramide Ae5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e5“Avenanthramide B was found to be more actively biosynthesized and metabolized than avenanthramide A”
Claim · model-written summary
Radiolabeled avenanthramide B was incorporated into the cell wall fraction of oat leaves.
- Taxon
- OatAvena sativae0
- Compound
- avenanthramide Be6
- Outcome
- incorporated into the cell wall fractione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e6“Radiolabeled avenanthramide B was incorporated into the cell wall fraction”
Claim · model-written summary
99% of the incorporated activity was released by alkaline treatment.
- Taxon
- OatAvena sativae0
- Treatment
- alkaline treatmente7
- Outcome
- incorporated activitye7
- Value
- 99%e7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e7“99% of incorporated activity was released by alkaline treatment”
Claim · model-written summary
High-molecular-weight compounds derived from avenanthramide B were released by alkaline treatment.
- Taxon
- OatAvena sativae0
- Treatment
- alkaline treatmente1
- Compound
- avenanthramide Be1
- Outcome
- high-molecular-weight compounds derived from avenanthramide Be1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“Gel filtration indicated that high-molecular-weight compounds derived from avenanthramide B were released by alkaline treatment”
Claim · model-written summary
Catalase, salicylhydroxamic acid and sodium ascorbate suppressed the decrease in labeled avenanthramides in oat leaves.
- Taxon
- OatAvena sativae0
- Treatment
- catalase, salicylhydroxamic acid, and sodium ascorbatee1
- Outcome
- decrease in stable-isotope-labeled avenanthramidese1
- Direction
- suppressede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“The decrease in stable-isotope-labeled avenanthramides was suppressed by catalase, salicylhydroxamic acid, and sodium ascorbate”
Claim · model-written summary
Peroxidase involvement in avenanthramide metabolism is suggested (author interpretation).
- Taxon
- OatAvena sativae0
- Outcome
- metabolisme1
- Qualifier
- involvement of peroxidasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“suggesting the involvement of peroxidase in the metabolism”
Claim · model-written summary
Elicitor treatment induced peroxidase activity that accepts avenanthramide B as a substrate in apoplastic fractions.
- Taxon
- OatAvena sativae0
- Organ / stage
- apoplastic fractionse1
- Treatment
- elicitor treatmente1
- Gene
- peroxidasee1
- Compound
- avenanthramide Be1
- Outcome
- peroxidase activity that accepts avenanthramide B as a substratee1
- Direction
- inducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“peroxidase activity that accepts avenanthramide B as a substrate was induced in apoplastic fractions by elicitor treatment”
Claim · model-written summary
Multiple basic isoperoxidases appeared in elicitor-treated oat leaves on activity staining after isoelectric focusing.
- Taxon
- OatAvena sativae0
- Organ / stage
- elicitor-treated leavese1
- Gene
- isoperoxidasese1
- Outcome
- appearance of multiple basic isoperoxidasese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oat leaves”
e1“The appearance of multiple basic isoperoxidases was observed by activity staining with 3-amino-9-ethylcarbazole coupled with isoelectric focusing of proteins from elicitor-treated leaves”
Claim · model-written summary
Accumulated avenanthramides are further metabolized in apoplasts of oat leaves by inducible isoperoxidases (author interpretation).
- Taxon
- oat leavesAvena sativae1
- Organ / stage
- apoplastse1
- Gene
- inducible isoperoxidasese1
- Outcome
- further metabolizede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“accumulated avenanthramides are further metabolized in apoplasts in oat leaves by inducible isoperoxidases”