WRINKLED1 Is Subject to Evolutionary Conserved Negative Autoregulation

Abstract

High accumulation of storage compounds such as oil and starch are economically important traits of most agricultural crops. The genetic network determining storage compounds composition in crops has been the target of many biotechnological endeavors. Especially WRINKLED1 (WRI1), a well-known key transcription factor involved in the allocation of carbon into oil, has attracted much interest. Here we investigate the presence of an autoregulatory system involving WRI1 through transient expression in Nicotiana benthamiana leaves. Different lengths of the Arabidopsis WRI1 promotor region were coupled to a GUS reporter gene and the activity was measured when combined with constitutive expression of different WRI1 homologs from Arabidopsis thaliana , oat ( Avena sativa L.), yellow nutsedge (Cyperus esculentus L.), and potato ( Solanum tuberosum L.). We could show that increasing levels of each WRI1 homolog reduced the transcriptional activity of the Arabidopsis WRI1 upstream region. Through structural analysis and domain swapping between oat and Arabidopsis WRI1, we were able to determine that the negative autoregulation was clearly dependent on the DNA-binding AP2-domains. A DNA/protein interaction assay showed that AtWRI1 is unable to bind to its corresponding upstream region indicating non-direct interaction in vivo . Taken together, our results demonstrate a negative feedback loop of WRI1 expression and that it is an indirect interaction most likely caused by downstream targets of WRI1. We also show that it is possible to release WRI1 expression from this autoregulation by creating semi-synthetic WRI1 homologs increasing the potential use of WRI1 in biotechnological applications.

A Tree Peony Trihelix Transcription Factor PrASIL1 Represses Seed Oil Accumulation

“…The Agrobacterium-mediated transient expression is an advantageous system to study gene expression due to time-efficiency compared to stable transformation systems (Wroblewski et al, 2005). Additionally, several studies have successfully demonstrated that N. benthamiana leaf tissue can be used for transient expression of genes involved in FA synthesis and TAG accumulation to affect their metabolism ( Grimberg et al, 2015;Ma et al, 2015Ma et al, , 2016An et al, 2017;Snell et al, 2019;Behera et al, 2021). Here, we transiently expressed PrASIL1 under the control of dual CaMV 35S promoters in N. benthamiana leaves.…”

Identification of Targets of Transcription Factor WRINKLED1-Like Related to Lipid Biosynthesis From Marine Microalga Dunaliella parva

“…A transcriptional regulation model supported a viewpoint that interaction of 14-3-3 protein with AtWRI1 enhanced the transcriptional activity through protein stabilization (Kong and Ma, 2018a). A negative feedback loop of WRI1 expression was an indirect interaction most possibly caused by downstream targets of WRI1 (Snell et al, 2019). The increasing levels of different WRI1 homologs (from Avena sativa L., Cyperus esculentus L., Arabidopsis thaliana and Solanum tuberosum L.) reduced the transcriptional activity of Arabidopsis WRI1 promotor region (Snell et al, 2019).…”

Functional and Predictive Structural Characterization of WRINKLED2, A Unique Oil Biosynthesis Regulator in Avocado

“…The functional role of Zm WRI2 remains to be examined. Similarly, IDR3 is absent in yellow nutsedge ( Cyperus esculentus ) WRI1 ( Ce WRI1), although it retained its functional role in oil biosynthesis ( Grimberg et al, 2015 ) and showed autoregulatory effect on the AtWRI1 promoter ( Snell et al, 2019 ). Hence, it is possible that Pa WRI2 is still able to activate the target genes in a similar manner to the transactivation mechanism shown by Ce WRI1.…”