Tesis doctoral de Ana Lázaro Somoza
The coordination of flowering time with seasonal and developmental cues is critical to maximize reproductive success in plants. In this work we have characterised components in two different mechanisms involved in the floral repression in arabidopsis. in one hand, we have isolated two early flowering mutations, esd1/arp6 and swc6, affecting putative orthologues of components of the yeast swr1 chromatin remodelling complex. We found that esd1/arp6 and swc6 are required for maintaining the expression of the flc repressor to levels that inhibit flowering. genetic and physical interactions between swc6 and esd1 have been demonstrated in this study, suggesting that both proteins act in the same complex. Besides, we have established that esd1/arp6 and swc6 are required for both histone h3 acetylation and h3k4 trimethylation on flc chromatin. Altogether, the results obtained suggest that swc6 and esd1 are part of an arabidopsis swr1 chromatin remodelling complex involved in the regulation of diverse aspects of plant development, including floral repression through the activation of flc and flc-like genes. on the other hand, we found the early in short days 6 (esd6) mutant in a screening for mutations that accelerate flowering time in arabidopsis and showed that it was affected in the hos1 locus, which encodes a ring finger-containing protein that works as an e3 ubiquitin ligase. The esd6/hos1 mutation showed a strong requirement of a functional co protein for its early flowering phenotype under long days. Besides, co and hos1 physically interact in vitro and in vivo, and hos1 regulates co abundance, particularly during the daylight period. Accordingly, the hos1 mutation causes a shift in the typical long day pattern of the ft transcript, starting to rise four hours after dawn. In addition, hos1 interacts synergistically with cop1, another regulator of co protein stability, in the control of flowering time. Taken together, these results indicate that hos1 is involved in regulating co abundance ensuring that co activation of ft occurs only when the light period reaches a certain length and preventing precocious flowering in arabidopsis.
Datos académicos de la tesis doctoral ««caracterización genética y molecular de mecanismos de represión floral en arabidopsis».«
- Título de la tesis: «caracterización genética y molecular de mecanismos de represión floral en arabidopsis».
- Autor: Ana Lázaro Somoza
- Universidad: Autónoma de Madrid
- Fecha de lectura de la tesis: 27/04/2011
Dirección y tribunal
- Director de la tesis
- Rafael Rivilla Palma
- Tribunal
- Presidente del tribunal: salomé Prat monguió
- pedro Crevillen lomas (vocal)
- rosa adela Arroyo García (vocal)
- isabel Diaz (vocal)