Abstract
The effects of Cd, Cu, and Ni ions on chloroplast gene expression were studied in 7-day-old barley ( Hordeum vulgare L.) seedlings. Toxicity of heavy metals (HM) was estimated from their effects on root and shoot growth and from the accumulation of HM in roots and leaves of seedlings grown in roll culture. Root growth was affected by HM to a higher extent than shoot growth. A statistically significant inhibition of root growth was observed at concentrations of all studied HM ≥100 μM. Leaf growth was inhibited by Cu and Ni at concentrations ≥400 μM, while the inhibitory effect of Cd on leaf growth was observed at concentrations ≥100 μM. The translocation of Cu from roots to shoots of barley seedlings proceeded slower than the accumulation of Cu in roots. Unlike Cu, Ni was actively accumulated by shoots in addition to its strong absorption by roots. Using the run-on transcription and RT-PCR (reverse transcription-polymerase chain reaction), we showed that HM at a concentration of 100 μM regulated the expression of individual chloroplast genes. The presence of either Cd, Cu, or Ni ions in the plant growth solution enhanced transcription of rpl16, rpl23 , and rpl12 genes encoding ribosomal proteins, and of ndhA encoding the subunit 1 of plastid NADH-plastoquinone oxidoreductase. Transcription of sixteen other studied plastid genes was not affected by HM. The activation of transcription of the studied genes was not always accompanied by an increase in the transcript copy number. Northern blot analysis showed that Cd impaired the splicing of rpl16 , a chloroplast gene that contains an intron. Thus, this study proves that HM regulate not only the transcriptional activity of chloroplast genes but also the splicing of rpl16 transcripts.
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Claims 13
Claim · model-written summary
Root growth was more affected than shoot growth by heavy metals.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Outcome
- Root growthe0
- Direction
- higher extente0
- Comparator
- shoot growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Root growth was affected by HM to a higher extent than shoot growth”
t0“barley seedlings”
Claim · model-written summary
All heavy metals significantly inhibited root growth at at least 100 μM.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- all studied HM ≥100 μMe0
- Outcome
- root growthe0
- Direction
- inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A statistically significant inhibition of root growth was observed at concentrations of all studied HM ≥100 μM”
t0“barley seedlings”
Claim · model-written summary
Cu inhibited leaf growth at at least 400 μM.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf growth was inhibited by Cu and Ni at concentrations ≥400 μM”
t0“barley seedlings”
Claim · model-written summary
Ni inhibited leaf growth at at least 400 μM.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf growth was inhibited by Cu and Ni at concentrations ≥400 μM”
t0“barley seedlings”
Claim · model-written summary
Cd inhibited leaf growth at at least 100 μM.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- Cde0
- Outcome
- leaf growthe0
- Direction
- inhibitorye0
- Qualifier
- ≥100 μMe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the inhibitory effect of Cd on leaf growth was observed at concentrations ≥100 μM”
t0“barley seedlings”
Claim · model-written summary
Cu accumulated faster in roots than it was translocated to shoots.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- translocation of Cu from roots to shootse0
- Direction
- slowere0
- Comparator
- accumulation of Cu in rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The translocation of Cu from roots to shoots of barley seedlings proceeded slower than the accumulation of Cu in roots”
t0“barley seedlings”
Claim · model-written summary
Ni accumulated actively in shoots and was strongly absorbed by roots.
- Taxon
- barleyHordeum vulgaret0
- Organ / stage
- shootse0
- Outcome
- Ni was actively accumulated by shootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ni was actively accumulated by shoots in addition to its strong absorption by roots”
t0“barley seedlings”
Claim · model-written summary
Cd enhanced rpl16, rpl23, rpl12 and ndhA transcription.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- Cde0
- Outcome
- transcription of rpl16, rpl23 , and rpl12 genese0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“either Cd, Cu, or Ni ions in the plant growth solution enhanced transcription of rpl16, rpl23 , and rpl12 genes encoding ribosomal proteins, and of ndhA”
t0“barley seedlings”
Claim · model-written summary
Cu enhanced rpl16, rpl23, rpl12 and ndhA transcription.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- Cue0
- Outcome
- transcription of rpl16, rpl23 , and rpl12 genese0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“either Cd, Cu, or Ni ions in the plant growth solution enhanced transcription of rpl16, rpl23 , and rpl12 genes encoding ribosomal proteins, and of ndhA”
t0“barley seedlings”
Claim · model-written summary
Ni enhanced rpl16, rpl23, rpl12 and ndhA transcription.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- Nie0
- Outcome
- transcription of rpl16, rpl23 , and rpl12 genese0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“either Cd, Cu, or Ni ions in the plant growth solution enhanced transcription of rpl16, rpl23 , and rpl12 genes encoding ribosomal proteins, and of ndhA”
t0“barley seedlings”
Claim · model-written summary
Sixteen other plastid genes showed no transcription response to heavy metals.
- Taxon
- barleyHordeum vulgaret0
- Treatment
- HMe0
- Outcome
- Transcription of sixteen other studied plastid genese0
- Direction
- not affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcription of sixteen other studied plastid genes was not affected by HM”
t0“barley seedlings”
Claim · model-written summary
Transcription activation did not always raise transcript copy number.
- Taxon
- barleyHordeum vulgaret0
- Outcome
- transcript copy numbere0
- Direction
- not always accompanied by an increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The activation of transcription of the studied genes was not always accompanied by an increase in the transcript copy number”
t0“barley seedlings”
Claim · model-written summary
Cd impaired rpl16 splicing.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cd impaired the splicing of rpl16”
t0“barley seedlings”
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