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Dissecting the gene regulatory networks behind carbon allocation in plants

ex situ studies on combinatorial and subdomains effects of seed transcription factors

Snell, Per (2019). Dissecting the gene regulatory networks behind carbon allocation in plants. Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2019:75
ISBN 978-91-7760-468-6
eISBN 978-91-7760-469-3
[Doctoral thesis]

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Abstract

Plants store excess energy and metabolites derived from photosynthesis in a variety of storage compounds with starch, protein and triacyglycerol (oil, TAG) being the most common. As humans, we are completely dependent on these compounds either directly as food or indirectly, as materials for large number of goods or feed for animals. With an increased interest in sustainable production systems and the need to feed and clothe a growing population in a changing environment, the need for a better understanding of how plants allocate carbon for storage is increasingly important.

One key transcription factor involved in the accumulation of TAG into seeds is WRINKLED1 (WRI1). Using a transient gene expression system together with promoter-reporter gene constructs in Nicotiana benthamiana leaves, it was found that WRI1 is negatively regulating its own expression. This was further investigated by domain swapping between WRI1 homologs from diverse plant species to reveal that this mechanism was intrinsic to the tandem DNA binding AP2-domains of WRI1. Fluorescent electrophoretic mobility shift assay (fEMSA) was employed using purified WRI1 showing that WRI1 is unable to directly interact with its own upstream region.

During seed development, non-endospermic seeds accumulate large amounts of oil in the embryo during later stages of embryo development. This is known to be regulated by several master regulators commonly called the LAFL-network (LEAFY COTYLEDON1 (LEC1), ABSCISSIC ACID INSENSITIVE3 (ABI3), FUSCA3 (FUS3) and LEC2). Using transient expression in N. benthamiana leaves it was discovered that LEC1 significantly influences the transactivation ability of LEC2 and especially ABI3. Not only is LEC1 modulating the ability of ABI3 to induce NbWRI1 expression, but also a large set of key genes involved in embryo morphogenesis. This suggests that LEC1 and ABI3 tightly collaborate to drive the embryo development from middle to late stage and the transition between morphogenesis to the acquisition of storage compounds.

With the purpose of investigating the differences in carbon partitioning between oat (Avena sativa) which is unique among the cereals in storing significant amount of oil in the endosperm with wheat (Triticum aestivum) that has basically no endosperm oil AsWRI1 was transformed into wheat. The resulting transformant lines showed a significantly altered seed phenotype with increased oil accumulation, disrupted endosperm development and reduced sink strength.

Authors/Creators:Snell, Per
Title:Dissecting the gene regulatory networks behind carbon allocation in plants
Subtitle:ex situ studies on combinatorial and subdomains effects of seed transcription factors
Alternative abstract:
LanguageAbstract
UNSPECIFIED

Växter lagrar överskottsenergi och metaboliter från fotosyntesen i ett flertal olika
former med stärkelse, protein och triacyglycerol (olja, TAG) som de vanligaste. Vi
människor är helt beroende av denna inlagring, antingen direkt i form av mat eller
foder, eller indirekt, som material för ett stort antal produkter. Med ett ökat intresse för
hållbara produktionssystem och behovet av att föda och klä en växande befolkning i en
allt mer föränderlig miljö, ökar stadigt behovet av att bättre förstå hur växter styr
inlagringen av kol.

En viktig transkriptionsfaktor involverad i ansamlingen av TAG i frön är
WRINKLED1 (WRI1). Genom att använde ett transient uttryck av
transkriptionsfaktorer tillsammans med en promotordriven rapportgen i blad från
Nicotiana benthamiana, konstaterades det att WRI1 reglerar negativt sitt eget uttryck.
Detta undersöktes ytterligare genom att byta regioner mellan WRI1-homologer vilket
avslöjade att denna mekanism var associerad med de DNA-bindande dubbla AP2-
domänerna i WRI1. Fluorescent electrophoretic mobility shift assay (fEMSA) visade
att WRI1 inte kan interagera direkt med sin egen uppströmsregion.

Under fröutveckling lagrar vissa frön stora mängder olja i embryot vilket sker sent i
embryoutvecklinegn. Detta regleras av flera så kallade huvudregulatorer som
tillsammans bildar LAFL-nätverket (LEAFY COTYLEDON1 (LEC1), ABSCISSIC
ACID INSENSITIVE3 (ABI3), FUSCA3 (FUS3) och LEC2). Genom transient uttryck
av dessa huvudregulatorer i blad från N. benthamiana upptäcktes att LEC1 signifikant
påverkar transaktiveringsförmågan hos LEC2 och och i synnerhet hos ABI3. LEC1
modulerar inte bara ABI3s förmåga att inducera uttryck av NbWRI1, utan också en stor
uppsättning nyckelgener involverade i embryomorfogenesen. Detta antyder att LEC1
och ABI3 tätt samarbetar för att driva stora delar av embryoutveckling och övergången
mellan morfogenes till förvärv av lagringsmolekyler.

I syfte att undersöka skillnaderna i kollagring mellan spannmål som kan lagra olja i
endospermet såsom havre (Avena sativa) och de som inte kunde göra det, såsom vete
(Triticum aestivum) transformerades vete med AsWRI1. De resulterande linjerna
uppvisade en signifikant förändrad fröfenotyp med ökad oljeackumulering, störd
endospermutvecklingen och reducerad förmåga till kolinlagring.

Series/Journal:Acta Universitatis Agriculturae Sueciae (1652-6880)
Year of publishing :2019
Number:2019:75
Number of Pages:104
Papers/manuscripts:
NumberReferences
ISnell*, P., Grimberg, Å., Carlsson, A. S., Hofvander, P. (2019). WRINKLED1 Is Subject to Evolutionary Conserved Negative Autoregulation. Frontiers in Plant Science. 10, pp. 387.
IIGrimberg*, Å., Wilkinson, M., Snell, P., De Vos, R. P., GonzálezThuillier, I., Tawfike, A., Ward J. L., Carlsson, A. S., Shewry, P., Hofvander, P. (2019). Transitions in wheat endosperm metabolism upon transcriptional induction of oil synthesis by oat endosperm WRINKLED1. (Submitted).
IIISnell, P., Grimberg, Å., Hofvander, P. (2019). LEC1 regulate accumulation of seed storage compounds through interaction with ABI3. (Manuscript)
IVSnell, P., Grimberg, Å., Hofvander, P. (2019). Interaction between NF-Y and B3-family TFs differentially regulates key steps of embryo development. (Manuscript
VSnell, P., Berg, H., Grimberg, Å., Carlsson, A, Hofvander, P. (2019). Dissection of members of the AP2-domain transcription factors reveal mechanisms behind target specificity. (Manuscript)
Place of Publication:Alnarp
Publisher:Department of Plant Breeding, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-468-6
ISBN for electronic version:978-91-7760-469-3
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Article category:Other scientific
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Plant Biotechnology
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 404 Agricultural Biotechnology > Genetics and Breeding
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Developmental Biology
Keywords:gene regulatory networks, AFL-subfamily, genetic engineering, gene regulation, biotechnology, autoregulation
URN:NBN:urn:nbn:se:slu:epsilon-p-102652
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-102652
ID Code:16457
Faculty:LTV - Fakulteten för landskapsarkitektur, trädgårds- och växtproduktionsvetenskap
Department:(LTJ, LTV) > Department of Plant Breeding (from 130101)
Deposited By: SLUpub Connector
Deposited On:21 Nov 2019 12:43
Metadata Last Modified:23 Aug 2020 20:53

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