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Doctoral Thesis
DOI
10.11606/T.46.2007.tde-04122014-182053
Document
Author
Full name
Elaine Cristina Favaro
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2007
Supervisor
Committee
Quaggio, Ronaldo Bento (President)
Colepicolo, Pio
Oliveira, Carla Columbano de
Pinna, Gladys Flávia de Albuquerque Melo de
Sluys, Marie Anne van
Title in Portuguese
Estudo da função dos genes Pumilio de Arabidopsis durante o desenvolvimento vegetal
Keywords in Portuguese
Arabidopsis thaliana
Controle traducional
Expressão gênica
Genetica molecular
Meristemas
Plantas transgênicas
Proteínas PUF, Desenvolvimento vegetal (Estudo)
Abstract in Portuguese
A família PUF é um conjunto de proteínas que se ligam a mRNA regulando sua estabilidade e tradução em processos chave do desenvolvimento. Entre as 25 proteínas de Arabidopsis contendo as repetições PUF, três delas, APUM-I, APUM-2 e APUM-3, apresentam ~90% de identidade e colocalizam temporal e espacialmente nos meristemas apical e axilares de caule, zona de elongação da raiz e no periciclo durante a formação de calos e de raízes laterais, além de estames e polens. Ensaios de RT-PCR mostraram que a relação de expressão entre eles é a mesma em todos os órgãos analisados. Além disso, plantas nocautes apum-1- e apum-2- não apresentam fenótipo alterado, sugerindo redundância funcional. Plantas com a expressão dessas proteínas afetadas por RNA antisense apresentaram folhas cloróticas e reduzidas, raízes mais curtas e menos ramificadas e baixa fertilidade, fenótipo semelhante ao de plantas que superexpressam KRP-2, um inibidor de CDK. O transcrito KRP-2 apresenta um elemento de ligação AraPum no 3'-UTR sugerindo ser um possível alvo para APUM. Em adição, plantas antisense têm aumento de transcritos KRP-2 em relação a selvagens. Assim, foi proposto que essas proteínas agem coordenando a formação de folhas e raízes pela influência na tradução de KRP-2. A função ancestral das proteínas PUF de manter o ciclo celular em detrimento da diferenciação, parece ser conservada em plantas.
Title in English
Study of PUMILIO genes function of Arabidopsis during plant developrnent
Keywords in English
Arabidopsis thaliana
Meristems
Molecular genetic
Plant developrnent
PUF proteins
Translational control
Abstract in English
The PUF family is a group of conserved proteins that bind to rnRNAs regulating its stability and translation in key developrnental processes. Among the twenty five Arabidopsis proteins with PUF repeats, we found that three highly similar members, APUM-I, APUM-2 and APUM-3 (~90% identity) and co-localize spatially and temporally in the shoot apical and axillaries meristems, root elongation zone and pericycle during callus and lateral root formation, as well as stamens and pollens. RTPCR assays showed that these proteins have similar expression profiles in ali organs analyzed. Moreover, plant apum-1 and apum-2 knockouts have no detectably altered phenotype, suggesting a functional redundancy between them. Plants in which APUM-I, APUM-2 and APUM-3 expression were reduced through antisense RNA, showed chlorotic and reduced leaves, shorter and less ramificated roots and low fertility. This phenotype is similar to that of plants over-expressing the KRP-2 gene, a CDK inhibitor. An AraPum binding element at 3'-UTR of the KRP-2 transcript suggests that it may be a possible target for APUM. In addition, in comparison to wild-type plants, antisense plants have increased KRP-2 transcripts levels. We proposed that APUM proteins act by coordinating leaf and root formation by way of influencing KRP-2 transiation. The ancestral function of PUF proteins in the maintenance of the cell cycle, to detriment of differentiation, seems to be conserved in plants.
 
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Publishing Date
2014-12-04
 
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