Navigation Links
At long last, scientists figure out how plants grow

It has been one of the great mysteries in plant science.

Scientists have known since 1885 that the plant growth hormone auxin exists. They've known of its dramatic effects on plant growth and development since the 1930s. But only now do scientists know how it works.

In this week's Nature, Indiana University Bloomington biologists Mark Estelle, Nihal Dharmasiri and Sunethra Dharmasiri identify TIR1 as the protein that, with auxin, influences how and when plant cells grow and divide. In the same issue, scientists in the United Kingdom report a virtually identical result.

"How auxin works has been a holy grail in plant science," said Estelle, who led the research. "This was something even Charles Darwin considered, if only in spirit. That we've all been trying to figure it out for so long makes this latest discovery very satisfying."

Estelle said the finding is important for basic plant science, but may also lead to new insight into how related proteins function in animals, including humans.

In a 2001 report (also in Nature), Estelle and colleagues showed that the protein TIR1 acts to increase the expression of certain growth-related genes.

The scientists had not known at the time that TIR1 interacts directly with auxin (also known as indoleacetic acid, or IAA). With that finding, the scientists can now envision a complete life history for the growth hormone. Auxin is produced in the tips of plant shoots and branches. The hormone travels downward toward the roots. It migrates into plant cell nuclei, where it is picked up by the TIR1 portion of a four-protein complex called SCF(TIR1). SCF(TIR1) and auxin binds to yet another protein that represses the expression of a particular set of genes. And it's this complex of auxin, SCF(TIR1) and the repressor that signals enzymes to destroy the repressor, thereby turning on the repressed gene.

"The key interaction is between TIR1 and the repressor," Estelle said. "Nihal was able to get that to work in a test tube, but the interaction would only occur if he added auxin to the solution."

Auxin may stick around awhile, but it is eventually broken down by natural cell processes.

The scientists used the common plant model Arabidopsis thaliana (wall cress) for their experiments. They also expressed TIR1 in insect cell cultures, to make sure that the binding of TIR1 to auxin is not directly influenced by other plant cell proteins.

Auxins influence a wide variety of plant processes. For example, they are the hormones that cause roots to grow downward and flowers to track the moving sun. Auxins also stop the growth of lateral branches. Since auxins are produced in shoot tips, lopping off the tip can cause numerous side shoots to appear, giving a plant a denser, more sculpted look.

Auxin also promotes fruit development. In strawberries, for example, auxin produced by the developing seeds promotes the growth of a red and juicy fruit.

Another protein called ABP1 (Auxin Binding Protein 1) has previously been shown to bind auxin. But unlike TIR1 and auxin, it remains unclear whether the pairing of ABP1 and auxin actually stimulates plant growth.

The research reported by Estelle, Dharmasiri and Dharmasiri was funded by grants from the National Science Foundation, the National Institutes of Health and the U.S. Department of Energy.

To speak with Estelle, please call 812-856-1216 or e-mail him at maestell@indiana.edu.

"The F-box protein TIR1 is an auxin receptor," Nature, v. 435, no. 7040


'"/>

Source:Indiana University


Related biology news :

1. Wisconsin scientists grow critical nerve cells
2. UCSB scientists probe sea floor venting to gain understanding of early life on Earth
3. UAB scientists discover the origin of a mysterious physical force
4. Fox Chase Cancer Center scientists identify immune-system mutation
5. Weizmann Institute scientists develop a new approach for directing treatment to metastasized prostate cancer in the bones.
6. U-M scientists find genes that control growth of common skin cancer
7. UCLA scientists transform HIV into cancer-seeking missile
8. RNA project to create language for scientists worldwide
9. Carnegie Mellon scientists develop tool that uses MRI to visualize gene expression in living animals
10. To control germs, scientists deploy tiny agents provocateurs
11. Leprosy microbes lead scientists to immune discovery
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:1/12/2017)... January 12, 2017 A new report by Allied Market Research, ... global biometric technology market is expected to generate revenue of $10.72 billion by 2022, ... Continue Reading ... Allied Market Research Logo ...      (Logo: http://photos.prnewswire.com/prnh/20140911/647229) In ...
(Date:1/6/2017)... 2017  SomaLogic announced today that it has ... by iCarbonX, the China -based ... Digital Health Ecosystem that can define each person,s ... biological, behavioral and psychological data, the Internet and ... SomaLogic will provide proteomics data and applications expertise ...
(Date:1/3/2017)... , Jan. 3, 2017 Onitor, provider of ... of Onitor Track, an innovative biometric data-driven program designed ... this month at the 2017 Consumer Electronics Show (CES) ... In the U.S., the World Health Organization (WHO), ... two-thirds of adults who are overweight or obese. WHO ...
Breaking Biology News(10 mins):
(Date:1/21/2017)... , Jan. 21, 2017   Boston Biomedical ... compounds designed to target cancer stemness pathways, today presented ... compound, napabucasin, at the 2017 American Society of Clinical ... Francisco . In a Phase ... agent designed to inhibit cancer stemness pathways by targeting ...
(Date:1/20/2017)... January 20, 2017 http://www.Financialbuzz.com ... one of leading causes of death worldwide. There were ... number of cancer related deaths increased gradually over time, ... incidence rate of various cancers continues to drive demand ... report by Global Market Insights, Inc. cancer biological therapy ...
(Date:1/19/2017)... and HOUSTON , ... ("NX Prenatal") today announced the formation of its ... leading clinicians and industry veterans who enhance the ... as it accelerates development of its novel prenatal ... provide medical, clinical and strategic guidance for the ...
(Date:1/19/2017)... ... January 19, 2017 , ... ... vigilance software to leading biopharmaceutical and medical device manufacturers and regulators, is proud ... 21 CFR Part 11-compliant email client designed to provide product vigilance departments with ...
Breaking Biology Technology: