Abstract
We present studies aimed at determining the types and frequencies of mutations induced in the barley genome after treatment with chemical (N-methyl-N-nitrosourea, MNU) and physical (gamma rays) mutagens. We created M(2) populations of a doubled haploid line and used them for the analysis of mutations in targeted DNA sequences and over an entire barley genome using TILLING (Targeting Induced Local Lesions in Genomes) and AFLP (Amplified Fragment Length Polymorphism) technique, respectively. Based on the TILLING analysis of the total DNA sequence of 4,537,117bp in the MNU population, the average mutation density was estimated as 1/504kb. Only one nucleotide change was found after an analysis of 3,207,444bp derived from the highest dose of gamma rays applied. MNU was clearly a more efficient mutagen than gamma rays in inducing point mutations in barley. The majority (63.6%) of the MNU-induced nucleotide changes were transitions, with a similar number of G>A and C>T substitutions. The similar share of G>A and C>T transitions indicates a lack of bias in the repair of O(6)-methylguanine lesions between DNA strands. There was, however, a strong specificity of the nucleotide surrounding the O(6)-meG at the -1 position. Purines formed 81% of nucleotides observed at the -1 site. Scanning the barley genome with AFLP markers revealed ca. a three times higher level of AFLP polymorphism in MNU-treated as compared to the gamma-irradiated population. In order to check whether AFLP markers can really scan the whole barley genome for mutagen-induced polymorphism, 114 different AFLP products, were cloned and sequenced. 94% of bands were heterogenic, with some bands containing up to 8 different amplicons. The polymorphic AFLP products were characterised in terms of their similarity to the records deposited in a GenBank database. The types of sequences present in the polymorphic bands reflected the organisation of the barley genome.
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Claims 12
Claim · model-written summary
MNU induced an average mutation density of 1/504kb in the barley genome by TILLING
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- MNUe0
- Outcome
- average mutation densitye0
- Value
- 1/504kbe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Based on the TILLING analysis of the total DNA sequence of 4,537,117bp in the MNU population, the average mutation density was estimated as 1/504kb”
t0“barley genome”
Claim · model-written summary
Only one nucleotide change was found in the barley genome at the highest gamma-ray dose
- Taxon
- barleyHordeum vulgaret0
- Treatment
- gamma rayse0
- Outcome
- nucleotide changee0
- Value
- onee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Only one nucleotide change was found after an analysis of 3,207,444bp derived from the highest dose of gamma rays applied”
t0“barley genome”
Claim · model-written summary
MNU was a more efficient mutagen than gamma rays in inducing point mutations in barley
- Taxon
- barleyHordeum vulgaree0
- Treatment
- MNUe0
- Outcome
- point mutationse0
- Direction
- more efficiente0
- Comparator
- gamma rayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“MNU was clearly a more efficient mutagen than gamma rays in inducing point mutations in barley”
t0“barley genome”
Claim · model-written summary
Transitions made up 63.6% of MNU-induced nucleotide changes in barley
- Taxon
- barleyHordeum vulgaret0
- Treatment
- MNUe0
- Outcome
- transitionse0
- Value
- 63.6%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The majority (63.6%) of the MNU-induced nucleotide changes were transitions”
t0“barley genome”
Claim · model-written summary
G>A and C>T substitutions occurred in a similar number among MNU-induced changes in barley
- Taxon
- barleyHordeum vulgaret0
- Outcome
- number of G>A and C>T substitutionse0
- Qualifier
- similare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with a similar number of G>A and C>T substitutions”
t0“barley genome”
Claim · model-written summary
The similar share of G>A and C>T transitions indicates no strand bias in the repair of O(6)-methylguanine lesions in barley
- Taxon
- barleyHordeum vulgaret0
- Compound
- O(6)-methylguaninee0
- Outcome
- lack of bias in the repaire0
- Qualifier
- between DNA strandse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The similar share of G>A and C>T transitions indicates a lack of bias in the repair of O(6)-methylguanine lesions between DNA strands”
t0“barley genome”
Claim · model-written summary
Purines formed 81% of nucleotides observed at the -1 site next to the O(6)-methylguanine lesion in barley
- Taxon
- barleyHordeum vulgaret0
- Outcome
- Purinese0
- Value
- 81%e0
- Qualifier
- of nucleotides observed at the -1 sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Purines formed 81% of nucleotides observed at the -1 site”
t0“barley genome”
Claim · model-written summary
A strong specificity of the nucleotide surrounding the O(6)-meG lesion at the -1 position was observed in barley
- Taxon
- barleyHordeum vulgaret0
- Outcome
- specificity of the nucleotide surrounding the O(6)-meGe0
- Qualifier
- at the -1 positione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was, however, a strong specificity of the nucleotide surrounding the O(6)-meG at the -1 position”
t0“barley genome”
Claim · model-written summary
MNU-treated barley showed about three times higher AFLP polymorphism than the gamma-irradiated population
- Taxon
- barleyHordeum vulgaret0
- Treatment
- MNU-treatede0
- Outcome
- AFLP polymorphisme0
- Direction
- highere0
- Value
- three timese0
- Comparator
- gamma-irradiated populatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Scanning the barley genome with AFLP markers revealed ca. a three times higher level of AFLP polymorphism in MNU-treated as compared to the gamma-irradiated population”
t0“barley genome”
Claim · model-written summary
About 94% of AFLP bands in barley were heterogenic
- Taxon
- barleyHordeum vulgaret0
- Outcome
- bands were heterogenice0
- Value
- 94%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“94% of bands were heterogenic, with some bands containing up to 8 different amplicons”
t0“barley genome”
Claim · model-written summary
Some AFLP bands in barley contained up to 8 different amplicons
- Taxon
- barleyHordeum vulgaret0
- Outcome
- bands containinge0
- Value
- up to 8 different ampliconse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“94% of bands were heterogenic, with some bands containing up to 8 different amplicons”
t0“barley genome”
Claim · model-written summary
The sequence types in polymorphic AFLP bands reflected the organisation of the barley genome
- Taxon
- barleyHordeum vulgaret0
- Outcome
- types of sequences present in the polymorphic bandse0
- Qualifier
- reflected the organisation of the barley genomee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The types of sequences present in the polymorphic bands reflected the organisation of the barley genome”
t0“barley genome”