Abstract
A functional screen in Escherichia coli was established to identify potato genes coding for proteins involved in transitory starch degradation. One clone isolated had a sequence very similar to a recently described chloroplast-targeted beta-amylase of Arabidopsis. Expression of the gene in E. coli showed that the protein product was a functional beta-amylase that could degrade both starch granules and solubilized amylopectin, while import experiments demonstrated that the beta-amylase was imported and processed into pea chloroplasts. To study the function of the protein in transitory starch degradation, transgenic potato plants were generated where its activity was reduced using antisense techniques. Analysis of plants reduced in the presence of this beta-amylase isoform showed that their leaves had a starch-excess phenotype, indicating a defect in starch degradation. In addition, it was shown that the antisense plants degraded only 8-30% of their total starch, in comparison with 50% in the wild type, over the dark period. This is the first time that a physiological role for a beta-amylase in plants has been demonstrated.
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Claims 4
Claim · model-written summary
Antisense-reduced beta-amylase potato plants had leaves with a starch-excess phenotype.
- Taxon
- potato
Solanum tuberosume1 - Organ / stage
- leavese2
- Treatment
- antisense techniquese1
- Gene
- beta-amylasee2
- Outcome
- starch-excess phenotypee2
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“transgenic potato plants were generated where its activity was reduced using antisense techniques”
e2“Analysis of plants reduced in the presence of this beta-amylase isoform showed that their leaves had a starch-excess phenotype, indicating a defect in starch degradation”
Claim · model-written summary
Antisense potato plants degraded only 8-30% of their total starch over the dark period, compared with 50% in wild type.
- Taxon
- potatoSolanum tuberosume1
- Treatment
- antisense techniquese1
- Outcome
- total starche3
- Direction
- lowerinferrede3
- Value
- 8-30%e3
- Qualifier
- 50% in the wild type, over the dark periode3
- Comparator
- wild typee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“transgenic potato plants were generated where its activity was reduced using antisense techniques”
e3“the antisense plants degraded only 8-30% of their total starch, in comparison with 50% in the wild type, over the dark period”
Claim · model-written summary
Expressed beta-amylase degraded both starch granules and solubilized amylopectin.
- Taxon
- potatoSolanum tuberosume1
- Gene
- beta-amylasee4
- Outcome
- degrade both starch granules and solubilized amylopectine4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“transgenic potato plants were generated where its activity was reduced using antisense techniques”
e4“Expression of the gene in E. coli showed that the protein product was a functional beta-amylase that could degrade both starch granules and solubilized amylopectin”
Claim · model-written summary
The beta-amylase was imported and processed into pea chloroplasts.
- Taxon
- potatoSolanum tuberosume1
- Organ / stage
- pea chloroplastse5
- Gene
- beta-amylasee5
- Outcome
- imported and processed into pea chloroplastse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“transgenic potato plants were generated where its activity was reduced using antisense techniques”
e5“import experiments demonstrated that the beta-amylase was imported and processed into pea chloroplasts”
The same questions in other papers
loss of function · quality: sugar starch · Solanum tuberosum (potato)Positive and negative results
7 papers in the same direction as this paper · 5 in the opposite direction
- positive
- positive
- no effect
9 papers more in this group
See all 13 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.