Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana
Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana
View/Type of Scholarly Publication
DissertationDate of Exam
10.10.2012Date of Publication
31.10.2012Advisor
Dörmann, PeterCo-Referee
Bartels, DorotheaMetadata
Show full item record
Citable Links 
Abstract
Seeds are major components of the human diet and seed oil represents a source of renewable and environmentally friendly replacements for fossil-based raw materials. During maturation seeds accumulate storage reserves to support the growth of the seedling before it gains its photosynthetic activity. The main storage reserves are oil in the form of triacylglycerols, proteins, and carbohydrates in the form of starch. Increasing the seed size and therefore storage reserve content is of major economical and agricultural importance. In this study we investigated the effects of alteration in seed development gene expression on storage allocation in seeds of Arabidopsis thaliana. New alleles of the seed development genes FIE1, PHE1, MINI3, and IKU2 were isolated and the homozygous mutant lines of the candidate genes were characterized. While the amount of storage proteins and sucrose was similar to the WT controls, the oil content was strongly reduced in all mutants to varying extents. This finding indicates that the carbon flow from carbohydrates to fatty acids biosynthesis is affected. To investigate the effects of the overexpression of FIE, PHE1, MINI3, and IKU2 on seed size and storage reserve accumulation, cDNAs encoding the candidate genes were overexpressed in Arabidopsis thaliana ecotype Col-0 using the embryo-specific glycinin promoter from soybean. Thus, the transgenes under control of the glycinin promoter, and the endogenous genes are differentially expressed, spatially and temporally. While the overexpression of FIE, PHE1, and MINI3 did not have any effects on seed size and storage reserve accumulation, IKU2-OE lines displayed a strong increase in seed size and oil content, but no change in protein and sucrose content. Moreover, non-transgenic segregant seeds of a heterozygous IKU2-OE line also showed an increase in seed size and oil content indicating a maternal effect of IKU2-OE overexpression in the seed coat or silique of the heterozygous plants. The increase in seed size and oil content was only observed in seeds of heterozygous IKU2-OE lines but not in homozygous seeds. RT-PCR analysis showed that IKU2 is highly expressed in seeds of heterozygous IKU2-OE lines, but is co-suppressed in homozygous IKU2-OE lines, which show similar low expression level as the control Col-0-EV. The increase in seed size of heterozygous IKU2-OE seeds was associated with a reduction in total seed yield per plant compared to the empty vector controls, while the siliques size and number of seeds per silique were not affected. It has been previously shown that the seed specific overexpression of seed development genes using strong promoters induces an increase in seed size associated with developmental abnormalities in the transgenic plants. However, the overexpression of the same genes under control of truncated or mutated promoters induces an increase in seed size without detrimental effects on plant development. Therefore, it might be possible to overcome the negative correlation between seed size and seed yield per plant by overexpression IKU2 using a modified glycinin promoter. The future goals of this study are the overexpression of IKU2 in oilseed crops such as soybean and rapeseed with the aim to increase the seed size and oil content in the transgenic lines.
Classification (DDC)
630 Landwirtschaft, VeterinärmedizinFatihi, Abdelhak: Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana. - Bonn, 2012. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-30222
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-30222
@phdthesis{handle:20.500.11811/5400,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-30222,
author = {{Abdelhak Fatihi}},
title = {Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2012,
month = oct,
note = {Seeds are major components of the human diet and seed oil represents a source of renewable and environmentally friendly replacements for fossil-based raw materials. During maturation seeds accumulate storage reserves to support the growth of the seedling before it gains its photosynthetic activity. The main storage reserves are oil in the form of triacylglycerols, proteins, and carbohydrates in the form of starch. Increasing the seed size and therefore storage reserve content is of major economical and agricultural importance. In this study we investigated the effects of alteration in seed development gene expression on storage allocation in seeds of Arabidopsis thaliana. New alleles of the seed development genes FIE1, PHE1, MINI3, and IKU2 were isolated and the homozygous mutant lines of the candidate genes were characterized. While the amount of storage proteins and sucrose was similar to the WT controls, the oil content was strongly reduced in all mutants to varying extents. This finding indicates that the carbon flow from carbohydrates to fatty acids biosynthesis is affected. To investigate the effects of the overexpression of FIE, PHE1, MINI3, and IKU2 on seed size and storage reserve accumulation, cDNAs encoding the candidate genes were overexpressed in Arabidopsis thaliana ecotype Col-0 using the embryo-specific glycinin promoter from soybean. Thus, the transgenes under control of the glycinin promoter, and the endogenous genes are differentially expressed, spatially and temporally. While the overexpression of FIE, PHE1, and MINI3 did not have any effects on seed size and storage reserve accumulation, IKU2-OE lines displayed a strong increase in seed size and oil content, but no change in protein and sucrose content. Moreover, non-transgenic segregant seeds of a heterozygous IKU2-OE line also showed an increase in seed size and oil content indicating a maternal effect of IKU2-OE overexpression in the seed coat or silique of the heterozygous plants. The increase in seed size and oil content was only observed in seeds of heterozygous IKU2-OE lines but not in homozygous seeds. RT-PCR analysis showed that IKU2 is highly expressed in seeds of heterozygous IKU2-OE lines, but is co-suppressed in homozygous IKU2-OE lines, which show similar low expression level as the control Col-0-EV. The increase in seed size of heterozygous IKU2-OE seeds was associated with a reduction in total seed yield per plant compared to the empty vector controls, while the siliques size and number of seeds per silique were not affected. It has been previously shown that the seed specific overexpression of seed development genes using strong promoters induces an increase in seed size associated with developmental abnormalities in the transgenic plants. However, the overexpression of the same genes under control of truncated or mutated promoters induces an increase in seed size without detrimental effects on plant development. Therefore, it might be possible to overcome the negative correlation between seed size and seed yield per plant by overexpression IKU2 using a modified glycinin promoter. The future goals of this study are the overexpression of IKU2 in oilseed crops such as soybean and rapeseed with the aim to increase the seed size and oil content in the transgenic lines.},
url = {https://hdl.handle.net/20.500.11811/5400}
}
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-30222,
author = {{Abdelhak Fatihi}},
title = {Alterations in the Expression of Seed Development Genes Affect Seed Size and Storage Compound Allocation in Arabidopsis thaliana},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2012,
month = oct,
note = {Seeds are major components of the human diet and seed oil represents a source of renewable and environmentally friendly replacements for fossil-based raw materials. During maturation seeds accumulate storage reserves to support the growth of the seedling before it gains its photosynthetic activity. The main storage reserves are oil in the form of triacylglycerols, proteins, and carbohydrates in the form of starch. Increasing the seed size and therefore storage reserve content is of major economical and agricultural importance. In this study we investigated the effects of alteration in seed development gene expression on storage allocation in seeds of Arabidopsis thaliana. New alleles of the seed development genes FIE1, PHE1, MINI3, and IKU2 were isolated and the homozygous mutant lines of the candidate genes were characterized. While the amount of storage proteins and sucrose was similar to the WT controls, the oil content was strongly reduced in all mutants to varying extents. This finding indicates that the carbon flow from carbohydrates to fatty acids biosynthesis is affected. To investigate the effects of the overexpression of FIE, PHE1, MINI3, and IKU2 on seed size and storage reserve accumulation, cDNAs encoding the candidate genes were overexpressed in Arabidopsis thaliana ecotype Col-0 using the embryo-specific glycinin promoter from soybean. Thus, the transgenes under control of the glycinin promoter, and the endogenous genes are differentially expressed, spatially and temporally. While the overexpression of FIE, PHE1, and MINI3 did not have any effects on seed size and storage reserve accumulation, IKU2-OE lines displayed a strong increase in seed size and oil content, but no change in protein and sucrose content. Moreover, non-transgenic segregant seeds of a heterozygous IKU2-OE line also showed an increase in seed size and oil content indicating a maternal effect of IKU2-OE overexpression in the seed coat or silique of the heterozygous plants. The increase in seed size and oil content was only observed in seeds of heterozygous IKU2-OE lines but not in homozygous seeds. RT-PCR analysis showed that IKU2 is highly expressed in seeds of heterozygous IKU2-OE lines, but is co-suppressed in homozygous IKU2-OE lines, which show similar low expression level as the control Col-0-EV. The increase in seed size of heterozygous IKU2-OE seeds was associated with a reduction in total seed yield per plant compared to the empty vector controls, while the siliques size and number of seeds per silique were not affected. It has been previously shown that the seed specific overexpression of seed development genes using strong promoters induces an increase in seed size associated with developmental abnormalities in the transgenic plants. However, the overexpression of the same genes under control of truncated or mutated promoters induces an increase in seed size without detrimental effects on plant development. Therefore, it might be possible to overcome the negative correlation between seed size and seed yield per plant by overexpression IKU2 using a modified glycinin promoter. The future goals of this study are the overexpression of IKU2 in oilseed crops such as soybean and rapeseed with the aim to increase the seed size and oil content in the transgenic lines.},
url = {https://hdl.handle.net/20.500.11811/5400}
}
The following license files are associated with this item:
