Navigation Links
Max Planck researchers make a breakthrough in plant stem cell research

Totipotent stem cells allow plants to build new organs throughout their whole life. But it has been unclear how hormones and genetic factors work together to prevent plants from having growth that is either stunted, or uncontrolled and tumor-like. Scientists from the Max Planck Institute for Developmental Biology have now uncovered a feedback mechanism, involving a growth-enhancing hormone and a regulatory protein, which controls the number of stem cells the plant produces. (Nature, December 22, 2005). The results are of great importance for all of stem cell research.

All above ground parts of a plant - leaves, stem, flowers, and seeds - ultimately are derived from cells of a small tissue at the tip of the shoot. Biologists call this tissue the "apical meristem", and it contains totipotent stem cells that are active throughout the life of the plant. Unlike the stem cells of animals, which can only produce specific kinds of tissue after the animal is past its embryonic stage, plant stem cells remain their totipotency and, therefore plants can continue growing over many years, developing new organs.

But this ability comes at a price. If the number of meristematic stem cells increases too quickly, then there could be uncontrolled growth, similar to cancer. On the other hand, if the stem cell pool shrinks too quickly, the plant could have stunted growth. In order to stay alive and reproduce, the plant needs to find the right balance in the number of its stem cells. Two regulatory mechanisms were found to be important for this process. The first involves growth-promoting hormones like auxin and cytokinin, known already for more than half a century. The second involves genetic factors, which were discovered at the University of Tübingen, Germany about a decade ago. Here it was shown that a gene called WUSCHEL has a key influence on how many cells in the apical meristem actually stay stem cells. However, until now, it was unclear how hormones and regulatory genes, such as WUSCHEL work together to maintain this fine balance at the tip of the shoot.

The working group led by Dr. Jan Lohmann at the Max Planck Institute for Developmental Biology in Tübingen, Germany has now solved this problem. The object of investigation was Arabidopsis thaliana, the "favorite plant" for molecular and genetic research, whose genome was sequenced years ago. Lohmannâ?super>TMs team now carried out elaborate genetic and biochemical experimentation, and thereby identified four genes, which might serve as a mechanistic connection between plant hormones and the genetic regulatory elements in meristem.

The researchers in Tübingen used gene expression analysis to show that the genes ARR5, ARR6, ARR7 and ARR 15, "Arabidopsis Response Regulators", are subject to genetic regulation via the WUSCHEL gene. In particular, WUSCHEL restricts the activity of ARR7 in the apical meristem. The ARR genes in turn carry out a particularly important task in hormonal regulation: they are part of a negative feedback loop, by which the growth-inducing plant hormone cytokinin limits its own influence. The study shows that the ARR genes play a direct role in regulation of the stem cell pool.

The hormone itself instigates the meristematic stem cells to split; at the same time, it activates various ARR genes, which break the cytokinin signal chain. Jan Lohmann explains that "WUSCHEL supports the cytokinin effect by stopping its negative feedback." That is also the reason for earlier observations, that Arabidopsis samples with defective WUSCHEL genes only develop very small meristems, and have trouble growing. The researchers in Tübingen have now discovered the same effect in mutants whose ARR7 gene is constitutively active.

Cytokinin can only have its full growth-promoting effect in tissue in which the WUSCHEL regulatory gene is active. "Meristematic regulation is a fabulous example of how the effects of free circulating hormon es can be limited to a particular tissue," Lohmann says. Only with this kind of mechanism, is it possible that the same hormone has different effects in different tissues, depending on which genetic conditions it encounters.


'"/>

Source:Max-Planck-Gesellschaft


Related biology news :

1. NYU researchers simulate molecular biological clock
2. Vital step in cellular migration described by UCSD medical researchers
3. ASU researchers finds novel chemistry at work to provide parrots vibrant red colors
4. UCSD researchers maintain stem cells without contaminated animal feeder layers
5. Why do insects stop breathing? To avoid damage from too much oxygen, say researchers
6. New protein discovered by Hebrew University researchers
7. First real-time view of developing neurons reveals surprises, say Stanford researchers
8. Agilent Technologies releases automated literature search tool for biology researchers
9. Self-assembled nano-sized probes allow Penn researchers to see tumors through flesh and skin
10. Yale researchers identify molecule for detecting parasitic infection in humans
11. US life expectancy about to decline, researchers say
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/2/2017)... Feb. 2, 2017   TapImmune, Inc. ... company specializing in the development of innovative peptide ... of cancer and metastatic disease, announced today it ... manufacturing of a second clinical lot of TPIV ... receptor alpha. The manufactured vaccine product will be ...
(Date:2/1/2017)... Massachusetts , February 1, 2017 IDTechEx ... events on emerging technology, announces the availability of a new report, ... Continue Reading ... ... in industrial and collaborative robots. Source: IDTechEx Report "Sensors for Robotics: ...
(Date:1/26/2017)... PANAMA CITY , Jan. 26, 2017  Crossmatch, ... today unveiled a new solution aimed at combatting fraud, ... The solution was introduced at the Action on Disaster ... a key meeting point for UN agencies and foreign ... Fraud, waste and abuse are a largely ...
Breaking Biology News(10 mins):
(Date:2/23/2017)...  In Atlanta, it seems everyone has a chance to ... create an expressive and dynamic community unlike any other. The ... to it. With their newest salon in ... to carry on that tradition with a unique, fresh approach ... salon is the newest of 13 nationwide locations, each of ...
(Date:2/23/2017)... Minn. , Feb. 23, 2017  Imanis ... new product line of oncolytic vaccinia viruses for ... Corporation as part of Genelux,s proprietary, vaccinia virus-based ... are excited to enter into a partnership with ... selected oncolytic vaccinia viruses for use in research," ...
(Date:2/23/2017)... , ... February 23, 2017 ... ... announced today that in a published evaluation of multiple immunoassay-based threat detection ... Department of Energy Laboratory, PathSensors’ CANARY® biosensor threat detection technology was found ...
(Date:2/23/2017)... ... ... Today, researchers can fast-track sample collection and analysis for ... or SNPs of interest) using one, easy-to-collect saliva sample. With the addition of ... and other relevant biomarkers can be extensively studied through a non-invasive sample type. ...
Breaking Biology Technology: