Abstract
The suggestion that brassinosteroids (BRs) have a negative regulatory role in de-etiolation is based largely on correlative evidence, which includes the de-etiolated phenotypes of, and increased expression of light-regulated genes in, dark-grown mutants defective in BR biosynthesis or response. However, we have obtained the first direct evidence which shows that endogenous BR levels in light-grown pea seedlings are increased, not decreased, in comparison with those grown in the dark. Similarly, we found no evidence of a decrease in castasterone (CS) levels in seedlings that were transferred from the dark to the light for 24 h. Furthermore, CS levels in the constitutively de-etiolated lip1 mutant are similar to those in wild-type plants, and are not reduced as is the case in the BR-deficient lkb plants. Unlike lip1, the pea BR-deficient mutants lk and lkb are not de-etiolated at the morphological or molecular level, as they exhibit neither a de-etiolated phenotype or altered expression of light-regulated genes when grown in the dark. Similarly, dark-grown WT plants treated with the BR biosynthesis inhibitor, Brz, do not exhibit a de-etiolated phenotype. In addition, analysis of the lip1lkb double mutant revealed an additive phenotype indicative of the two genes acting in independent pathways. Together these results strongly suggest that BR levels do not play a negative-regulatory role in de-etiolation in pea.
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Claims 10
Claim · model-written summary
Endogenous BR levels were higher in light-grown than dark-grown pea seedlings.
- Taxon
- pea
Lathyrus oleraceust0 - Organ / stage
- seedlingse0
- Outcome
- endogenous BR levelse0
- Direction
- increasede0
- Comparator
- those grown in the darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“endogenous BR levels in light-grown pea seedlings are increased, not decreased, in comparison with those grown in the dark.”
t0“pea”
Claim · model-written summary
CS levels did not show evidence of a decrease after dark-to-light transfer.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- seedlingse0
- Outcome
- castasterone (CS) levelse0
- Direction
- no evidence of a decreasee0
- Qualifier
- 24 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we found no evidence of a decrease in castasterone (CS) levels in seedlings that were transferred from the dark to the light for 24 h.”
t0“pea”
Claim · model-written summary
CS levels in lip1 were similar to wild type.
- Taxon
- peaLathyrus oleraceust0
- Material
- lip1 mutante0
- Outcome
- CS levelse0
- Direction
- similare0
- Comparator
- wild-type plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CS levels in the constitutively de-etiolated lip1 mutant are similar to those in wild-type plants, and are not reduced as is the case in the BR-deficient lkb plants.”
t0“pea”
Claim · model-written summary
CS levels in lkb plants were reduced relative to wild type.
- Taxon
- peaLathyrus oleraceust0
- Material
- lkb plantse0
- Outcome
- CS levelse0
- Direction
- reducede0
- Comparator
- wild-type plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CS levels in the constitutively de-etiolated lip1 mutant are similar to those in wild-type plants, and are not reduced as is the case in the BR-deficient lkb plants.”
t0“pea”
Claim · model-written summary
lk did not de-etiolate morphologically or molecularly in darkness.
- Taxon
- peaLathyrus oleraceust0
- Material
- lke0
- Outcome
- not de-etiolated at the morphological or molecular levele0
- Qualifier
- when grown in the darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the pea BR-deficient mutants lk and lkb are not de-etiolated at the morphological or molecular level, as they exhibit neither a de-etiolated phenotype or altered expression of light-regulated genes when grown in the dark.”
t0“pea”
Claim · model-written summary
lkb did not de-etiolate morphologically or molecularly in darkness.
- Taxon
- peaLathyrus oleraceust0
- Material
- lkbe0
- Outcome
- not de-etiolated at the morphological or molecular levele0
- Qualifier
- when grown in the darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the pea BR-deficient mutants lk and lkb are not de-etiolated at the morphological or molecular level, as they exhibit neither a de-etiolated phenotype or altered expression of light-regulated genes when grown in the dark.”
t0“pea”
Claim · model-written summary
Brz-treated dark-grown WT plants lacked a de-etiolated phenotype.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- BR biosynthesis inhibitor, Brze0
- Outcome
- de-etiolated phenotypee0
- Direction
- do not exhibite0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dark-grown WT plants treated with the BR biosynthesis inhibitor, Brz, do not exhibit a de-etiolated phenotype.”
t0“pea”
Claim · model-written summary
The lip1lkb double mutant had an additive phenotype.
- Taxon
- peaLathyrus oleraceust0
- Material
- lip1lkb double mutante0
- Outcome
- additive phenotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“analysis of the lip1lkb double mutant revealed an additive phenotype indicative of the two genes acting in independent pathways.”
t0“pea”
Claim · model-written summary
The additive phenotype suggested independent gene pathways.
- Taxon
- peaLathyrus oleraceust0
- Material
- lip1lkb double mutante0
- Outcome
- independent pathwayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“analysis of the lip1lkb double mutant revealed an additive phenotype indicative of the two genes acting in independent pathways.”
t0“pea”
Claim · model-written summary
BR levels were interpreted as lacking a negative regulatory role in pea de-etiolation.
- Taxon
- peaLathyrus oleraceust0
- Compound
- BRe0
- Outcome
- de-etiolatione0
- Qualifier
- do not play a negative-regulatory rolee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Together these results strongly suggest that BR levels do not play a negative-regulatory role in de-etiolation in pea.”
t0“pea”