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SHI/STY-family members redundantly regulate auxin homeostasis in basal and higher plants

Eklund, Magnus (2009). SHI/STY-family members redundantly regulate auxin homeostasis in basal and higher plants. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2009:9
ISBN 978-91-86195-56-4
[Doctoral thesis]

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The hormone auxin plays fundamental roles in plant development by stimulating growth and differentiation of cells and tissues. Auxin action appears to rely on the formation of auxin gradients and/or concentration maxima, in large created by polar auxin transport. However, recent studies suggest that auxin synthesis also commence at sites of high auxin signaling and that spatiotemporal control of auxin biosynthesis may be required in the formation or maintenance of certain auxin maxima. The SHI/STY-family member STYLISH1 (STY1) has previously been shown to induce the activity of the auxin biosynthesis gene YUCCA4 in lateral organs of Arabidopsis thaliana. This thesis describe the functional characterization of members of the embryophyte specific SHI/STY-family in the model species A. thaliana and Physcomitrella patens. Phenotypic analysis of A. thaliana plants carrying mutations in SHI/STY-family genes revealed that the gene products act highly redundant and in a dose-dependent manner in flower and leaf development. Protein studies showed that SHI/STY proteins regulate auxin biosynthesis by acting as transcriptional activators interacting with the YUC4 promoter. Additionally, promoters of other auxin biosynthesis-related genes were activated by STY1. The sequence targeted by STY1 was identified by comparing target gene promoters. Mutations in the identified element abolished STY1-YUC4 interaction in yeast. A conserved promoter element was also discovered in most SHI/STY members, including STY1. This element was shown to be essential for gene expression in most aerial organs and could be the target of AP2/ERF-family members. Identical expression patterns and knock-out mutant phenotypes of the moss P. patens SHI/STY-family members indicated that they act redundantly, as in A. thaliana. The knock-out and overexpressor lines showed phenotypes related to reduced and increased auxin levels, respectively, and the overexpressor lines indeed displayed elevated auxin levels. The SHI/STY genes of moss and higher plants are very similar and we suggest that they perform conserved functions.

Authors/Creators:Eklund, Magnus
Title:SHI/STY-family members redundantly regulate auxin homeostasis in basal and higher plants
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2009
Number of Pages:84
ALLI. Kuusk, S., Sohlberg, J.J., Eklund, D.M. & Sundberg, E. (2006). Functionally redundant SHI family genes regulate Arabidopsis gynoecium development in a dose-dependent manner. The Plant Journal 47, 99-111. II. Eklund, D.M., Ståldal, V., Cierlik, I., Eriksson, C., Hiratsu, K., Ohme- Takagi, M., Sundström, F. J., Ezcurra, I. & Sundberg, E. The Arabidopsis thaliana STYLISH1 protein acts as a transcriptional activator regulating auxin biosynthesis. (manuscript). III. Eklund, D.M., Cierlik, I., Ståldal, V., Chandler, J & Sundberg, E. Expression of SHORT INTERNODES/STYLISH family genes in auxin biosynthesis zones of aerial organs is dependent of a GCC-box-like regulatory element. (manuscript). IV. §Eklund, D.M., §Thelander, M., Landberg, K., Ståldal, V., Nilsson, A., Johansson, M., Valsecchi, I., Kowalczyk, M., Ronne, H. & Sundberg, E. Physcomitrella patens orthologues of the Arabidopsis SHI/STY/LRP1 genes induce auxin accumulation and affect growth and development in moss. (manuscript). § Indicates shared first authorship
Place of Publication:Uppsala
ISBN for printed version:978-91-86195-56-4
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:arabidopsis thaliana, bryophyta, auxins, biosynthesis, plant developmental stages, homeostasis, genes, gene expression, transcription, transcription factors
Keywords:Arabidopsis thaliana, auxin, biosynthesis, Physcomitrella patens, plant development, redundancy, SHI/STY-family, STYLISH1, transcription factor, transcriptional regulation
Permanent URL:
ID Code:1923
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Magnus Eklund
Deposited On:02 Feb 2009 00:00
Metadata Last Modified:02 Dec 2014 10:15

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