Abstract
The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C. Stress of 40/25C was given for seven days or continuously up to maturity. Kernels were analysed weekly for dry matter and extractable DNA. In addition the ploidy levels and the DNA content in intact cell nuclei were determined by flow cytometry. The dry matter reduction started immediately after heat treatment and reached, at maturity, 40% for temporary heat stress and 60% for permanent heat stress. The reduction of extractable DNA started later and was not as extensive. Endopolyploidy was found in all kernel tissues, namely embryo, endosperm and pericarp. In endosperm, 3C nuclei reached their maximum number at approximately 14-17 days, and cells with higher ploidy levels between 21 and 26 days after flowering. Later on 6C nuclei were dominant. The DNA content in intact cells of the endosperm reached a maximum 21 days after flowering. This maximum was lower for heat stress variants and decreased more rapidly. Heat stress can vary from year to year under field conditions. Since heat stress changes the ratio between embryo and endosperm DNA in the direction of a higher portion of embryo DNA at maturity, this has an influence on the measured content of GM DNA from GM pollen transfer into conventional maize fields.
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Claims 11
Claim · model-written summary
Temporary heat stress reduced kernel dry matter by 40% at maturity compared with control plants
- Material
- Spezie0
- Organ / stage
- kernelse0
- Treatment
- temporary heat stresse1
- Outcome
- dry mattere1
- Direction
- reductione1
- Value
- 40%e1
- Qualifier
- at maturitye1
- Comparator
- control plantse0
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e1“The dry matter reduction started immediately after heat treatment and reached, at maturity, 40% for temporary heat stress and 60% for permanent heat stress”
Claim · model-written summary
Permanent heat stress reduced kernel dry matter by 60% at maturity compared with control plants
- Material
- Spezie0
- Organ / stage
- kernelse0
- Treatment
- permanent heat stresse1
- Outcome
- dry mattere1
- Direction
- reductione1
- Value
- 60%e1
- Qualifier
- at maturitye1
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e1“The dry matter reduction started immediately after heat treatment and reached, at maturity, 40% for temporary heat stress and 60% for permanent heat stress”
Claim · model-written summary
Reduction of extractable DNA started later and was less extensive than the dry matter reduction in maize kernels
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e2“The reduction of extractable DNA started later and was not as extensive”
Claim · model-written summary
Endopolyploidy was found in embryo, endosperm and pericarp of maize kernels
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e3“Endopolyploidy was found in all kernel tissues, namely embryo, endosperm and pericarp”
Claim · model-written summary
In endosperm, 3C nuclei reached their maximum number at approximately 14-17 days after flowering
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e4“In endosperm, 3C nuclei reached their maximum number at approximately 14-17 days, and cells with higher ploidy levels between 21 and 26 days after flowering. Later on 6C nuclei were dominant”
Claim · model-written summary
Cells with higher ploidy levels in endosperm occurred between 21 and 26 days after flowering
- Organ / stage
- endosperme4
- Outcome
- cells with higher ploidy levelse4
- Direction
- highere4
- Value
- between 21 and 26 days after floweringe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e4“In endosperm, 3C nuclei reached their maximum number at approximately 14-17 days, and cells with higher ploidy levels between 21 and 26 days after flowering. Later on 6C nuclei were dominant”
Claim · model-written summary
6C nuclei were dominant later in endosperm development
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e4“In endosperm, 3C nuclei reached their maximum number at approximately 14-17 days, and cells with higher ploidy levels between 21 and 26 days after flowering. Later on 6C nuclei were dominant”
Claim · model-written summary
Endosperm DNA content in intact cells reached a maximum 21 days after flowering
- Organ / stage
- endosperme5
- Outcome
- DNA content in intact cellse5
- Direction
- maximume5
- Value
- 21 days after floweringe5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e5“The DNA content in intact cells of the endosperm reached a maximum 21 days after flowering. This maximum was lower for heat stress variants and decreased more rapidly”
Claim · model-written summary
Heat stress lowered the maximum endosperm DNA content in intact cells
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e5“The DNA content in intact cells of the endosperm reached a maximum 21 days after flowering. This maximum was lower for heat stress variants and decreased more rapidly”
Claim · model-written summary
Heat stress caused endosperm DNA content in intact cells to decrease more rapidly
- Treatment
- heat stress variantse5
- Outcome
- DNA content in intact cells of the endosperme5
- Direction
- decreased more rapidlye5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e5“The DNA content in intact cells of the endosperm reached a maximum 21 days after flowering. This maximum was lower for heat stress variants and decreased more rapidly”
Claim · model-written summary
Heat stress shifted the embryo and endosperm DNA ratio toward a higher portion of embryo DNA at maturity
- Treatment
- heat stresse6
- Outcome
- ratio between embryo and endosperm DNAe6
- Direction
- higher portion of embryo DNAe6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The post-anthesis development of grow- ing maize kernels is strongly affected by heat stress. The maize cultivar ''Spezi'' was used to quantify this effect in kernels from 14 days after flowering until maturity. Day/night temperature of control plants was 25/20C”
e6“Since heat stress changes the ratio between embryo and endosperm DNA in the direction of a higher portion of embryo DNA at maturity”
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