Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Size matters to a plant, but how is it controlled?

07.12.2005


Scientists at the John Innes Centre(JIC), Norwich, UK [1] today report a discovery that explains how plants control the size and development of their cells. Published on-line by the international journal PNAS [2] the report describes how a gene (called RHL1)[3] affects a plant cell’s ability to make multiple copies of its DNA, in turn affecting cell growth and overall plant development.



“Unlike the cells of animals, plant cells typically expand to up to 1,000 times their original size as they develop” says Dr Keiko Sugimoto-Shirasu (project leader at JIC). “We don’t know a lot about how this is controlled but it is often the result of the cell making multiple copies of its DNA (so-called endoreduplication), which then stimulates this massive cell growth. Our discovery has given us an exciting insight into how plant cells actually manage all these extra copies of DNA and shown us that the process is much more sophisticated than we imagined”.

The researchers at JIC were using the common weed Thale Cress (Arabidopsis thaliana) to study the control of cell size and the endoreduplication process. They identified a mutation (called hyp7) that caused seedlings to be dwarf, because their cells did not expand normally. When they compared the damaged gene, which causes the mutation, with known genes they discovered it is a gene that is known to affect root hair production on the roots of plants – hence its name root hairless or rhl.


Hyp7 (or rhl) has similarities to other known genes from animals and bacteria. In this case the genes are known to be important in DNA replication. In fact they have a very specific role in unravelling the DNA double helix to allow it to be copied (replicated). So it seems that the hyp7/rhl gene has a key part in enabling plant cells to make multiple copies of their DNA and so is vital to cell expansion and normal development[4].

Dr Sugimoto-Shirasu concludes, “our discovery is an exciting and important piece in the much larger jigsaw of understanding how plants, which are full of complex tissues and organs, develop from the same relatively simple starting point – the cell. The more we understand about plant development the better placed we are to modify crop plants to be more productive and less dependent on chemical and other inputs”.

1. The John Innes Centre (JIC), Norwich, UK is an independent, world-leading research centre in plant and microbial sciences. The JIC has over 800 staff and students. JIC carries out high quality fundamental, strategic and applied research to understand how plants and microbes work at the molecular, cellular and genetic levels. The JIC also trains scientists and students, collaborates with many other research laboratories and communicates its science to end-users and the general public. The JIC is grant-aided by the Biotechnology and Biological Sciences Research Council.

2. PNAS – Proceedings of the National Academy of Sciences USA. Online early edition is available at http://www.pnas.org/papbyrecent.shtml.
PNAS can be contacted at 202-334-1310 or PNASNews@nas.edu

3. RHL – roothairless – is one of a family of at least 3 plant genes that are important in determining root hair formation on plant roots. RHL1 produces a protein that is targeted to the nucleus of the plant cell but its function is unknown.

4. One strategy to increase cell size is for the plant cells to amplify their chromosomal DNA content through endoreduplication cycles. Although
endoreduplication is widespread in eukaryotes, we know very little about its molecular mechanisms. Successful progression of the endoreduplication cycle in Arabidopsis requires a plant homologue of archaeal DNA topoisomerase (topo) VI.

Hyp7 (hypocotyls 7) is a dwarf Arabidopsis mutant in which various large cell types that in the wild type normally endoreduplicate multiple times complete only the first two rounds of endoreduplication and stall at 8C. It was identified from a mutant screen for dark-grown short-hypocotyl phenotypes. HYP7 encodes the RHL1 (ROOT HAIRLESS 1) protein, and sequence analysis reveals that RHL1 has similarity to the mammalian DNA topoisomerase II. RHL1 shows DNA binding activity in vitro, and we have in vivo evidence that RHL1 forms a multiprotein complex with plant topoisomerase VI. RHL1 plays an essential role in the topoisomerase VI complex to modulate its function and that plant topoisomerase II and topoisomerase VI play distinct but overlapping roles during the mitotic cell cycle and endoreduplication cycle.

It seems the RHL protein plays an essential role in successive endocycles as a component of the plant topoisomerase VI complex and enables plant cells to unravel entangled chromosomes during endocycles above 8C.

Dr Keiko Sugimoto-Shirasu | alfa
Further information:
http://www.bbsrc.ac.uk
http://www.jic.ac.uk

More articles from Life Sciences:

nachricht New way to look at cell membranes could change the way we study disease
19.11.2018 | University of Oxford

nachricht Controlling organ growth with light
19.11.2018 | European Molecular Biology Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

New materials: Growing polymer pelts

19.11.2018 | Materials Sciences

Earthquake researchers finalists for supercomputing prize

19.11.2018 | Information Technology

Controlling organ growth with light

19.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>