Publicação
The role of auxin in the initiation of seed coat development in Arabidopsis thaliana
| Resumo: | Seed formation in Arabidopsis thaliana requires a coordinated development between embryo, endosperm and seed coat. While the first two structures are originated by a simultaneous fertilization event of egg and central cell, the seed coat is solely of sporophytic origin. Still, initiation of its development is triggered by the presence of the sexual endosperm. In fact, the type I MADS-box transcription factor, AGL62 is necessary to form an endosperm-derived signal that upon fertilization, triggers seed coat development. The nature of such signal is however still unknown. Symplastic connections between endosperm and seed coat are not known to exist, therefore phytohormones, due to their ability to actively cross cell membranes, are good candidates to be involved in this signaling process. Molecular evidence, such as gene expression studies, suggests that auxin is involved in seed coat development. In this study the role of this phytohormone in seed development, and more particularly in seed coat initiation were investigated. Reporter gene analysis revealed that auxin is present in all tissues of the ovule and seed throughout their development, and suggest that a fertilization-dependent increase in biosynthetic activity may be the initial drive for seed development. Additionally, it was found that auxin has the ability to induce autonomous seed formation, bypassing the developmental repression exerted by PcG proteins, in the absence of fertilization. Also, auxin partially rescued the phenotype of the agl62 mutant, which fails to develop a seed coat. Moreover, the results obtained here show that auxin is essential for correct cell specification and positioning in the embryo sac. Altogether, these results indicate that auxin has a predominant role in ovule and seed development and that this hormone seems to be involved in the pathway that leads to seed coat formation, most likely not as an exclusive participant. |
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| Autores principais: | Batista, Rita Adriano, 1990- |
| Assunto: | Embriologia vegetal Arabidopsis thaliana Biologia do desenvolvimento Teses de mestrado - 2013 |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Seed formation in Arabidopsis thaliana requires a coordinated development between embryo, endosperm and seed coat. While the first two structures are originated by a simultaneous fertilization event of egg and central cell, the seed coat is solely of sporophytic origin. Still, initiation of its development is triggered by the presence of the sexual endosperm. In fact, the type I MADS-box transcription factor, AGL62 is necessary to form an endosperm-derived signal that upon fertilization, triggers seed coat development. The nature of such signal is however still unknown. Symplastic connections between endosperm and seed coat are not known to exist, therefore phytohormones, due to their ability to actively cross cell membranes, are good candidates to be involved in this signaling process. Molecular evidence, such as gene expression studies, suggests that auxin is involved in seed coat development. In this study the role of this phytohormone in seed development, and more particularly in seed coat initiation were investigated. Reporter gene analysis revealed that auxin is present in all tissues of the ovule and seed throughout their development, and suggest that a fertilization-dependent increase in biosynthetic activity may be the initial drive for seed development. Additionally, it was found that auxin has the ability to induce autonomous seed formation, bypassing the developmental repression exerted by PcG proteins, in the absence of fertilization. Also, auxin partially rescued the phenotype of the agl62 mutant, which fails to develop a seed coat. Moreover, the results obtained here show that auxin is essential for correct cell specification and positioning in the embryo sac. Altogether, these results indicate that auxin has a predominant role in ovule and seed development and that this hormone seems to be involved in the pathway that leads to seed coat formation, most likely not as an exclusive participant. |
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