| 1. |
- Cierlik, Izabela
(författare)
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Novel insights into the action of SHI/STY transcriptional regulators during plant development
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One key player in plant organogenesis is the phytohormone auxin, and this thesis reveal that members of the SHI/STY gene family participate in the regulation of auxin homeostasis and organ development in Arabidopsis thaliana. Using inducible constructs, ChIP, and EMSA, we could show that the SHI/STY members act as transcriptional activators directly binding to the promoter of the auxin biosynthesis gene YUC4. Additional putative downstream targets were identified encoding transcription factors, other auxin biosynthesis enzymes and enzymes involved in cell wall modulations. This work also brings novel insight into SHI/STY-dependent regulation of cotyledon and leaf vascular patterning and stamen number. Detailed expression studies of SHI/STY genes and several downstream targets confirm their overlapping spatial and temporal expression pattern during cotyledon, leaf, stamen and gynoecium development, clearly supporting the partially redundant function of the SHI/STY family members during the development of these organs. In addition, the expression of SHI/STY members is partially mediated through a conserved motif in their promoter region, a GCC-box, which appears to be essential for SHI/STY expression in aerial organs. Furthermore, a group of putative upstream regulators belonging to the AP2/ERF family have been identified, which requires the GCC-box for their transcriptional regulation of the SHI/STY genes.
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| 2. |
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| 3. |
- Eklund, Magnus, et al.
(författare)
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Expression of Arabidopsis SHORT INTERNODES/STYLISH Family Genes in Auxin Biosynthesis Zones of Aerial Organs Is Dependent on a GCC Box-Like Regulatory Element
- 2011
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 157, s. 2069-2080
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Tidskriftsartikel (refereegranskat)abstract
- Auxin/indole-3-acetic acid (IAA) biosynthesis in Arabidopsis (Arabidopsis thaliana) plays a major role in growth responses to developmental and genetic signals as well as to environmental stimuli. Knowledge of its regulation, however, remains rudimentary, and few proteins acting as transcriptional modulators of auxin biosynthesis have been identified. We have previously shown that alteration in the expression level of the SHORT INTERNODES/STYLISH (SHI/STY) family member STY1 affects IAA biosynthesis rates and IAA levels and that STY1 acts as a transcriptional activator of genes encoding auxin biosynthesis enzymes. Here, we have analyzed the upstream regulation of SHI/STY family members to gain further insight into transcriptional regulation of auxin biosynthesis. We attempted to modulate the normal expression pattern of STY1 by mutating a putative regulatory element, a GCC box, located in the proximal promoter region and conserved in most SHI/STY genes in Arabidopsis. Mutations in the GCC box abolish expression in aerial organs of the adult plant. We also show that induction of the transcriptional activator DORNROSCHEN-LIKE (DRNL) activates the transcription of STY1 and other SHI/STY family members and that this activation is dependent on a functional GCC box. Additionally, STY1 expression in the strong drnl-2 mutant or the drn drnl-1 puchi-1 triple mutant, carrying knockdown mutations in both DRNL and its close paralogue DRN as well as one of their closest homologs, PUCHI, was significantly reduced, suggesting that DRNL regulates STY1 during normal plant development and that several other genes might have redundant functions.
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| 4. |
- Eklund, Magnus, et al.
(författare)
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The Arabidopsis thaliana STYLISH1 Protein Acts as a Transcriptional Activator Regulating Auxin Biosynthesis
- 2010
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 22:2, s. 349-363
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Tidskriftsartikel (refereegranskat)abstract
- The establishment and maintenance of auxin maxima in vascular plants is regulated by auxin biosynthesis and polar intercellular auxin flow. The disruption of normal auxin biosynthesis in mouse-ear cress ( Arabidopsis thaliana) leads to severe abnormalities, suggesting that spatiotemporal regulation of auxin biosynthesis is fundamental for normal growth and development. We have shown previously that the induction of the SHORT-INTERNODES/STYLISH (SHI/STY) family member STY1 results in increased transcript levels of the YUCCA (YUC) family member YUC4 and also higher auxin levels and auxin biosynthesis rates in Arabidopsis seedlings. We have also shown previously that SHI/STY family members redundantly affect development of flowers and leaves. Here, we further examine the function of STY1 by analyzing its DNA and protein binding properties. Our results suggest that STY1, and most likely other SHI/STY members, are DNA binding transcriptional activators that target genes encoding proteins mediating auxin biosynthesis. This suggests that the SHI/STY family members are essential regulators of auxin-mediated leaf and flower development. Furthermore, the lack of a shoot apical meristem in seedlings carrying a fusion construct between STY1 and a repressor domain, SRDX, suggests that STY1, and other SHI/STY members, has a role in the formation and/or maintenance of the shoot apical meristem, possibly by regulating auxin levels in the embryo.
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| 5. |
- Hueso Estornell, Leandro, et al.
(författare)
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SHI/STY Genes Affect Pre- and Post-meiotic Anther Processes in Auxin Sensing Domains in Arabidopsis
- 2018
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Ingår i: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- In flowering plants, mature sperm cells are enclosed in pollen grains formed in structures called anthers. Several cell layers surrounding the central sporogenous cells of the anther are essential for directing the developmental processes that lead to meiosis, pollen formation, and the subsequent pollen release. The specification and function of these tissues are regulated by a large number of genetic factors. Additionally, the plant hormone auxin has previously been shown to play important roles in the later phases of anther development. Using the R2D2 auxin sensor system we here show that auxin is sensed also in the early phases of anther cell layer development, suggesting that spatiotemporal regulation of auxin levels is important for early anther morphogenesis. Members of the SHI/STY transcription factor family acting as direct regulators of YUC auxin biosynthesis genes have previously been demonstrated to affect early anther patterning. Using reporter constructs we show that SHI/STY genes are dynamically active throughout anther development and their expression overlaps with those of three additional downstream targets, PAO5,EOD3 and PGL1. Characterization of anthers carrying mutations in five SHI/STY genes clearly suggests that SHI/STY transcription factors affect anther organ identity. In addition, their activity is important to repress periclinal cell divisions as well as premature entrance into programmed cell death and cell wall lignification, which directly influences the timing of anther dehiscence and the pollen viability. The SHI/STY proteins also prevent premature pollen germination suggesting that they may play a role in the induction or maintenance of pollen dormancy.
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| 7. |
- Saheed, Sefiu, et al.
(författare)
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Stronger induction of callose deposition in barley by Russian wheat aphid than bird cherry-oat aphid is not associated with differences in callose synthase or beta-1,3-glucanase transcript abundance
- 2009
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 135:2, s. 150-161
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Tidskriftsartikel (refereegranskat)abstract
- The effects of infestation by the bird cherry-oat aphid (BCA), (Rhopalosiphum padi L) and the Russian wheat aphid (RWA) (Diuraphis noxia Mordvilko) on callose deposition and transcription of genes related to callose accumulation were investigated in barley (Hordeum vulgare L. cv. Clipper). The BCA, which gives no visible symptoms, induced very limited callose deposition, even after 14 days of infestation. In contrast, RWA, which causes chlorosis, white and yellow streaking and leaf rolling, induced callose accumulation already after 24 h in longitudinal leaf veins. The deposition was pronounced after 72 h, progressing during 7 and 14 days of infestation. In RWA-infested source leaves, callose was also induced in longitudinal veins basipetal to the aphid-infested tissue, whereas in sink leaves, more callose deposition was found above the feeding sites. Eight putative callose synthase genes were identified in a database search, of which seven were expressed in the leaves, but with similar transcript accumulation in control and aphid-infested tissue. Five out of 12 examined beta-1,3-glucanases were expressed in the leaves. All five were upregulated in RWA-infested tissue, but only two in BCA-infested tissue, and to a lesser extent than by RWA. The results suggest that callose accumulation may be partly responsible for the symptoms resulting from RWA infestation and that a callose-inducing signal may be transported in the phloem. Furthermore, it is concluded that the absence of callose deposition in BCA-infested leaves is not because of a stronger upregulation of callose-degrading beta-1,3-glucanases in this tissue, as compared to RWA-infested leaves.
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