In research published online in Proceedings of the National Academy of Sciences the week of Aug. 20, the team found that one member of a family of proteins called transcription factors took control of a cascade of genes involved in forming wood, which includes a substance called lignin that binds fibers together and gives wood its strength.
The controller protein regulated gene expression on multiple levels, preventing abnormal or stunted plant growth. And it did so in a novel way.
The controller, a spliced variant of the SND1 family, was found in the cytoplasm outside the cell nucleus. This is abnormal, because transcription factor proteins are always in the nucleus. But when one of the four other proteins in its family group was present, the spliced variant was carried into the nucleus, where it bound to the family member, creating a new type of molecule that suppressed the expression of a cascade of genes.
“This is nothing that’s been observed before in plants,” says Dr. Vincent Chiang, co-director of NC State’s Forest Biotechnology Group with Dr. Ron Sederoff. Chiang’s research team was the first to produce a transgenic tree with reduced lignin. High lignin levels are desirable for lumber, but lignin is removed during the process of making paper or manufacturing biofuels.
Chiang, a professor in the College of Natural Resources, described the team’s finding as the long-sought path to understanding the hierarchy of gene regulation for wood formation.
Lead authors are Dr. Quanzi Li, senior research associate, who discovered the controller protein, and doctoral student Ying-Chung Lin, who carried out extensive experimental work, demonstrating with Li that the controller protein was carried into the nucleus.
The research was funded with a grant from the U.S. Department of Energy’s Office of Biological and Environmental Research.
Note to editors: An abstract of the study follows.
“Splice variant of the SND1 transcription factor is a dominant negative of SND1 members and their regulation in Populus trichocarpa”
Published: Online the week of Aug. 20 in Proceedings of the National Academy of Sciences
Authors: Quanzi Li, Ying-Chung Lin, Ying-Hsuan Sun, Jian Song, Hao Chen, Xing-Hai Zhang, Ronald R. Sederoff, and Vincent L. Chiang. All are members of the Forest Biotechnology Group in the Department of Forestry and Environmental Resources at North Carolina State University, except for Xing-Hai Zhang, who is with the Department of Biological Sciences at Florida Atlantic University.
Abstract: Secondary Wall-Associated NAC Domain 1s (SND1s) are transcription factors (TFs) known to activate a cascade of TF and pathway genes affecting secondary cell wall biosynthesis (xylogenesis) in Arabidopsis and poplars. Elevated SND1 transcriptional activation leads to ectopic xylogenesis and stunted growth. Nothing is known about the upstream regulators of SND1. Here we report the discovery of a stem-differentiating xylem (SDX)-specific alternative SND1 splice variant, PtrSND1-A2IR, that acts as a dominant negative of SND1 transcriptional network genes in Populus trichocarpa. PtrSND1-A2IR derives from PtrSND1-A2, one of the four fully spliced PtrSND1 gene family members (PtrSND1-A1, -A2, -B1, and -B2). Each full-size PtrSND1 activates its own gene, and all four full-size members activate a common MYB gene (PtrMYB021). PtrSND1-A2IR represses the expression of its PtrSND1 member genes and PtrMYB021. Repression of the autoregulation of a TF family member by its only splice variant has not previously been reported in plants. PtrSND1-A2IR lacks DNA binding and transactivation abilities but retains dimerization capability. PtrSND1-A2IR is localized exclusively in cytoplasmic foci. In the presence of any full-size PtrSND1 member, PtrSND1-A2IR is translocated into the nucleus exclusively as a heterodimeric partner with full-size PtrSND1s. Our findings are consistent with a model in which the translocated PtrSND1-A2IR lacking DNA-binding and transactivating abilities can disrupt the function of full-size PtrSND1s, making them nonproductive through heterodimerization, and thereby modulating the SND1 transcriptional network. PtrSND1-A2IR may contribute to transcriptional homeostasis to avoid deleterious effects on xylogenesis and plant growth.
Dr. Vincent Chiang | EurekAlert!
Fighting a destructive crop disease with mathematics
21.06.2017 | University of Cambridge
Unusual soybean coloration sheds a light on gene silencing
20.06.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology