Every vascular plant contains an extensive network of xylem and phloem, specialized tissues that respectively transport water and nutrients throughout the plant body. Untangling the processes that determine how these two types of vasculature develop has proven challenging, but a team led by Taku Demura of the RIKEN Biomass Engineering Program in Wako has now uncovered an important novel regulator of xylem formation1.
Several years ago, Demura and colleagues identified a family of seven VASCULAR-RELATED NAC-DOMAIN (VND) transcription factors; one of these, VND7, appears to activate a number of genes related to xylem development2. “The data suggest that VND7 likely functions as the principal regulator of vessel differentiation,” Demura says. However, the activity of this factor appears to depend closely on the proteins with which it partners, and his team has subsequently focused on identifying these co-regulators.
In their most recent screen, the researchers identified VNI2, a novel transcriptional regulator that physically interacts with VND7 and whose expression appears to correlate closely with vascular development in both root and stem tissue. However, although both VND7 and VNI2 are categorized as ‘NAC domain’ proteins, VNI2 exhibited one surprising difference from other members of its family. “It is known that most of the NAC transcription factors are transcriptional activators,” says Demura. “In contrast, VNI2 is a transcriptional repressor.”
Indeed, VNI2 appears to act primarily as an inhibitor of vascular development, and plants overexpressing this factor exhibited profound defects in xylem formation. These abnormalities were highly similar to those observed in plants overexpressing modified, inhibitory variants of VND7, further supporting a partnership between these two factors. In parallel, Demura and colleagues determined that VNI2 specifically represses several genes known to be induced by VND7 in the course of xylem differentiation.
These findings indicate that the VNI2–VND7 complex contributes directly to the timing and localization of vascular development, although this is most likely not the sole purpose of this repressor. “Our paper shows that VNI2 is expressed in various other cell types in addition to xylem vessels, and we want to know its other functions,” says Demura. Accordingly, their initial protein–protein interaction data suggest that VNI2 might pair with other, non-xylem-specific NAC proteins, whose functional characteristics remain enigmatic.
“We still need to study the VND genes [more closely],” says Demura, “for a better understanding of xylem cell differentiation. Since xylem cells are a major source of lignocellulosic biomass, such knowledge could be applied to potential renewable materials and biofuels.”
The corresponding author for this highlight is based at the Cellulose Production Research Team, RIKEN Biomass Engineering Program
1. Yamaguchi, M., Ohtani, M., Mitsuda, N., Kubo, M., Ohme-Takagi, M., Fukuda, H. & Demura, T. VND-INTERACTING2, a NAC domain transcription factor, negatively regulates xylem vessel formation in Arabidopsis. Plant Cell 22, 1249–1263 (2010).
2. Kubo, M., Udagawa, M., Nishikubo, N. Horiguchi, G., Yamaguchi, M., Ito, J., Mimura, T., Fukuda, H. & Demura, T. Transcription switches for protoxylem and metaxylem vessel formation. Genes & Development 19, 1855–1860 (2005).
gro-pr | Research asia research news
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences