Abstract
Synthesis of the wound-inducible alkaloid, nicotine, in roots of the allotetraploid species Nicotiana tabacum L. is strongly influenced by the presence of two non-allelic genes, A and B. Together, these loci affect baseline transcript levels of genes dedicated to secondary metabolism (e.g. PMT and A622) as well as genes with roles in separate areas of primary metabolism (e.g. ODC, ADC, SAMS — polyamines; QPT — pyridine nucleotide cycle). Experiments comparing high alkaloid variety NC 95 (AABB genotype) and near-isogenic low alkaloid N. tabacum variety LAFC 53 (aabb genotype) indicate that together, mutations in the A and B loci diminish, but do not ablate, the propensity of roots to increase transcript levels of genes involved in alkaloid metabolism after damage to aerial tissues or direct treatment with the wound hormone, methyl jasmonate. Accordingly, roots of aabb genotype can increase their nicotine content somewhat in response to these treatments. Additionally, we show that transcript levels of genes associated with polyamine metabolism (ODC, ADC, SamDC, SAMS and SS) but not alkaloid synthesis (PMT, QPT, A622) are elevated in leaves of N. tabacum in response to wounding. Moreover, respective increases in transcript levels of each gene are similar in wounded leaves of NC 95 and LAFC 53, suggesting that these increases are not controlled by combined action of genes encoded by the A and B loci. Further detailed analysis of wounded leaves of AABB genotype indicates that although transcript levels of these genes of polyamine metabolism and associated enzyme activities for ODC, ADC and SamDC, are markedly increased in leaves in response to wounding, putrescine levels remain unaltered whilst spermidine and spermine levels are reduced to 50–60% of controls levels, when analysed up to 6 h post-wounding. These observations may indicate that any wound-induced increases in polyamine biosynthesis that do occur in leaf cells during this time frame are consumed by metabolic reactions involved in repair and / or strengthening of wounded leaf tissues.
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Claims 9
Claim · model-written summary
A and B mutations diminished but did not eliminate root transcript induction after aerial wounding or methyl jasmonate.
- Taxon
- Nicotiana tabacum L.
Nicotiana tabacume1 - Material
- A and B locie0
- Organ / stage
- rootse0
- Treatment
- damage to aerial tissues or direct treatment with the wound hormone, methyl jasmonatee0
- Gene
- genes involved in alkaloid metabolisme0
- Outcome
- transcript levelse0
- Direction
- diminishe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mutations in the A and B loci diminish, but do not ablate, the propensity of roots to increase transcript levels of genes involved in alkaloid metabolism after damage to aerial tissues or direct treatment with the wound hormone, methyl jasmonate.”
e1“Nicotiana tabacum L.”
Claim · model-written summary
The aabb genotype increased root nicotine somewhat after the treatments.
- Taxon
- Nicotiana tabacum L.Nicotiana tabacume1
- Material
- aabb genotypee0
- Organ / stage
- rootse0
- Treatment
- these treatmentse0
- Outcome
- nicotine contente0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“roots of aabb genotype can increase their nicotine content somewhat in response to these treatments.”
e1“Nicotiana tabacum L.”
Claim · model-written summary
Wounding elevated leaf transcripts of polyamine-metabolism genes.
- Taxon
- N. tabacumNicotiana tabacume0
- Organ / stage
- leavese0
- Treatment
- woundinge0
- Gene
- ODC, ADC, SamDC, SAMS and SSe0
- Outcome
- transcript levelse0
- Direction
- elevatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transcript levels of genes associated with polyamine metabolism (ODC, ADC, SamDC, SAMS and SS) but not alkaloid synthesis (PMT, QPT, A622) are elevated in leaves of N. tabacum in response to wounding.”
Claim · model-written summary
Wounding did not elevate transcripts of alkaloid synthesis genes in leaves.
- Taxon
- N. tabacumNicotiana tabacume0
- Organ / stage
- leavese0
- Treatment
- woundinge0
- Gene
- PMT, QPT, A622e0
- Outcome
- transcript levelse0
- Direction
- no_changeinferrede0
- Qualifier
- but not alkaloid synthesise0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transcript levels of genes associated with polyamine metabolism (ODC, ADC, SamDC, SAMS and SS) but not alkaloid synthesis (PMT, QPT, A622) are elevated in leaves of N. tabacum in response to wounding.”
Claim · model-written summary
Wound-induced transcript increases were similar in NC 95 and LAFC 53 leaves.
- Material
- NC 95 and LAFC 53e0
- Organ / stage
- wounded leavese0
- Outcome
- increases in transcript levelse0
- Direction
- similare0
Not reportedTaxon
Verbatim
e0“respective increases in transcript levels of each gene are similar in wounded leaves of NC 95 and LAFC 53”
Claim · model-written summary
Wounding markedly increased polyamine gene transcripts and associated enzyme activities in AABB leaves.
- Taxon
- N. tabacumNicotiana tabacume1
- Material
- AABB genotypee2
- Organ / stage
- leavese0
- Treatment
- woundinge0
- Gene
- ODC, ADC and SamDCe0
- Outcome
- transcript levels of these genes of polyamine metabolism and associated enzyme activitiese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transcript levels of these genes of polyamine metabolism and associated enzyme activities for ODC, ADC and SamDC, are markedly increased in leaves in response to wounding”
e1“leaves of N. tabacum in response to wounding”
e2“wounded leaves of AABB genotype”
Claim · model-written summary
Leaf putrescine levels were unchanged up to six hours after wounding.
- Taxon
- N. tabacumNicotiana tabacume1
- Treatment
- woundinge0
- Outcome
- putrescine levelse0
- Direction
- remain unalterede0
- Qualifier
- up to 6 h post-woundinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“putrescine levels remain unaltered whilst spermidine and spermine levels are reduced to 50–60% of controls levels, when analysed up to 6 h post-wounding.”
e1“leaves of N. tabacum in response to wounding”
Claim · model-written summary
Leaf spermidine fell to 50–60% of controls after wounding.
- Taxon
- N. tabacumNicotiana tabacume1
- Treatment
- woundinge0
- Outcome
- spermidinee0
- Direction
- reducede0
- Value
- 50–60%e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“spermidine and spermine levels are reduced to 50–60% of controls levels, when analysed up to 6 h post-wounding.”
e1“leaves of N. tabacum in response to wounding”
Claim · model-written summary
Leaf spermine fell to 50–60% of controls after wounding.
- Taxon
- N. tabacumNicotiana tabacume1
- Treatment
- woundinge0
- Outcome
- spermine levelse0
- Direction
- reducede0
- Value
- 50–60%e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“spermidine and spermine levels are reduced to 50–60% of controls levels, when analysed up to 6 h post-wounding.”
e1“leaves of N. tabacum in response to wounding”
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