Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Crop scientists discover gene that controls fruit shape

14.03.2008
Crop scientists have cloned a gene that controls the shape of tomatoes, a discovery that could help unravel the mystery behind the huge morphological differences among edible fruits and vegetables, as well as provide new insight into mechanisms of plant development.

The gene, dubbed SUN, is only the second ever found to play a significant role in the elongated shape of various tomato varieties, said Esther van der Knaap, lead researcher in the study and assistant professor of horticulture and crop science at Ohio State University’s Ohio Agricultural Research and Development Center (OARDC) in Wooster.

The discovery was reported, as the cover article, in the March 14 issue of the journal Science.

One of the most diverse vegetable crops in terms of shape and size variations, tomatoes have evolved from a very small, round wild ancestor into the wide array of cultivated varieties — some large and segmented, some pear-shaped, some oval, some resembling chili peppers — available through most seed catalogs and for sale in supermarkets. However, very little is known about the genetic basis for such transformations in tomatoes, and virtually nothing has been discerned about morphological changes in other fruits and vegetables.

“Tomatoes are the model in this emerging field of fruit morphology studies,” van der Knaap pointed out. “We are trying to understand what kind of genes caused the enormous increase in fruit size and variation in fruit shape as tomatoes were domesticated. Once we know all the genes that were selected during that process, we will be able to piece together how domestication shaped the tomato fruit — and gain a better understanding of what controls the shape of other very diverse crops, such as peppers, cucumbers and gourds.”

One of the first pieces in van der Knaap’s fruit-development puzzle is SUN, which takes its name from the “Sun 1642” cultivated variety where it was found — an oval-shaped, roma-type tomato with a pointy end. The gene also turned out to be very common in elongated heirloom varieties, such as the Poblano pepper-like “Howard German” tomato.

“After looking at the entire collection of tomato germplasm we could find, we noticed that there were some varieties that had very elongated fruit shape,” van der Knaap explained. “By genetic analysis, we narrowed down the region of the genome that controls this very elongated fruit shape, and eventually narrowed down that region to a smaller section that we could sequence to find what kind of genes were present at that location.

“In doing that,” van der Knaap continued, “we identified one key candidate gene that was turned on at high levels in the tomato varieties carrying the elongated fruit type, while the gene was turned off in round fruit. And after we confirmed that observation in several other varieties, we found that this gene was always very highly expressed in varieties that carry very elongated fruit.”

Once SUN was identified, the next step involved proving whether this gene was actually responsible for causing changes in fruit shape. To do so, van der Knaap and her team conducted several plant-transformation experiments. When the SUN gene was introduced into wild, round fruit-bearing tomato plants, they ended up producing extremely elongated fruit. And when the gene was “knocked out” of elongated fruit-bearing plants, they produced round fruit similar to the wild tomatoes.

“SUN doesn’t tell us exactly how the fruit-shape phenotype is altered, but what we do know is that turning the gene on is very critical to result in elongated fruit,” van der Knaap said. “We can now move forward and ask the question: Does this same gene, or a gene that is closely related in sequence, control fruit morphology in other vegetables and fruit crops?”

Something else van der Knaap and her team found out is that SUN encodes a member of the IQ67 domain of plant proteins, called IQD12, which they determined to be sufficient — on its own — to make tomatoes elongated instead of round during the plant transformation experiments.

IQD12 belongs to a family of proteins whose discovery is relatively new in the world of biology. So new that IQD12 is only the second IQ67 protein-containing domain whose function in plants has been identified. The other one is AtIQD1, discovered in the plant model Arabidopsis thaliana, which belongs to the same family as broccoli and cabbage. In Arabidopsis, AtIQD1 increases levels of glucosinolate, a metabolite that Ohio State researchers are studying in broccoli for its possible role in inhibiting cancer (http://researchnews.osu.edu/archive/goodbroc.htm).

“Unlike AtIQD1, SUN doesn’t seem to be affecting glucosinolate levels in tomato, since these metabolites are not produced in plants of the Solanaceous family (which includes tomato, peppers, eggplant and other popular crops),” van der Knaap explained. “But there appears to be a common link between the two genes, which is that they may be regulating tryptophan levels in the plant. Thus, SUN may be telling us more about the whole process of diversification in fruits and across plant species, perhaps through its impact on plant hormones and/or secondary metabolites levels.”

In the process of identifying and cloning SUN, van der Knaap’s team was also able to trace the origin of this gene and the process by which it came to reside in the tomato genome.

Another unique characteristic of the SUN gene is that it affects fruit shape after pollination and fertilization, with the most significant morphological differences found in developing fruit five days after plant flowering. The only other fruit-shape gene previously identified — OVATE, a discovery by Cornell University plant breeder Steven Tanksley, van der Knaap’s advisor while she was a post-doctoral associate there — influences the future look of a fruit before flowering, early in the ovary development.

Esther van der Knaap | EurekAlert!
Further information:
http://www.osu.edu

More articles from Agricultural and Forestry Science:

nachricht Energy crop production on conservation lands may not boost greenhouse gases
13.03.2017 | Penn State

nachricht How nature creates forest diversity
07.03.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>