News section
home news forum careers events suppliers solutions markets resources directories advertise contacts search site plan
 
.
Genetic engineering tames drought, climate change

.

Basel, Switzerland
November 27, 2007

By Tanuja Rohatgi, Checkbiotech

Climate change is a major issue these days that has awaken the concerns of the world as natural catastrophes intensify. One of its most common catastrophes is drought. However, now, a team of researchers is nearing a solution.

Water is not only needed to drink, but to cultivate crops too. In some parts of the world, occurrence of drought year after year is having a disastrous effect on the agricultural production.

To circumvent the problems caused by drought, a team comprising of scientist from United States, Japan and Israel have successfully generated drought-tolerant plants.

The ground-breaking study led by Dr. Eduardo Blumwald’s laboratory at the University of California at Davis will be published on December 4 in the scientific journal the Proceedings of the National Academy of Science (PNAS).

Plants are receptive to the environment in which they grow and have evolved ways to respond or adapt to the changes in their surrounding. To counter the problem of water shortage due to drought conditions, plants usually close the pores in their leaves to avoid water loss.

In addition, during drought conditions, the plants will shed leaves to help prevent the further loss of water. While the leave shedding strategy helps them under drought conditions, it results in reduce yield of crops, which is of no consolation for farmers.

Dr. Blumwald and his team worked on the hypothesis that it should be possible to delay the drought-induced shedding of leaves. Senescence (shedding of leaves) is a built-in survival mechanism, which is normally activated in plants during drought conditions or change of season. Switching-on this signal helps plants adapt internally and withstand the stress caused by the drought conditions.

To generate drought tolerant transgenic plants, Dr. Blumwald and his team introduced a gene for isopentenyltransferase (IPT) enzyme. This was essential, because IPT leads to an increased amount of a plant growth regulator called cytokinin, which helps prevent plant senescence.

In an additional step, the IPT gene was coupled with another gene, which is activated during late maturation and/or stress and decreased during the onset of senescence. This strategy was aimed to make sure that the growing plant has enough cytokinin when it is about to enter the senescence stage.

Testing of transgenic plants

Once the transgenic tobacco plants were grown, the research teams then assessed the health of the plants in comparison to wild-type tobacco plants. The transgenic plants grown in greenhouse showed no difference in their appearance when compared with the wild-type tobacco plants. Also, they showed a normal development cycle including flowering.

Next, the plants were tested for their drought tolerance. Unlike the wild-type plants, which wilted and senesced progressively under drought conditions, the transgenic plants were only partially wilted, and showed no drought-induced senescence.

“While watering of wild-type plants could not recover them from drought stress, transgenic plants recovered completely and showed vigorous growth,” explained Dr. Blumwald. “Testing of biomass, soil water potential and water content of the plants clearly showed the superiority of transgenic plants over the wild-types during drought conditions.”

Once the testing of basic growth characteristics verified their hypothesis, the researchers then examined the expression of certain proteins in different parts of the leaves during varying experimental conditions. They found that indeed the production of cytokinin is responsible for the enhanced drought tolerance in the transgenic plants.

Further, Dr. Blumwald’s research looked at the mechanism behind the cytokinin-enhanced drought tolerance. Gene expression profiling is now used on a regular basis to check for change in gene patterns under different conditions. The genetically enhanced plants showed an increase in the expression of genes associated with maintenance of cell integrity during stress. All these factors confirm that the genetically engineered plants generated by Dr. Blumwald and his team are fit for drought conditions.

Equally important is the fact that transgenic plants can retain their photosynthetic activity - albeit at a reduced level during drought conditions - while also showing minimal yield loss. Thus, the strategy of introducing a drought tolerant gene in plants provides a big ray of hope to farmers who face severe drought and limited water supply for irrigation.

When asked about the next stage of the project, Dr. Blumwald told Checkbiotech, “We have developed a number of transgenic lines of plants expressing our constructs in rice, wheat and other important crops and are preparing material that will be tested in the greenhouse and the field.”

Dr. Blumwald understands the reservations that some have towards genetically modified crops, but adds, “Although this concern is viable, it will be impossible to keep plants from crossing with other species (if they are compatible in nature).”

However, he thinks this question is not of great concern where his plants are concerned, “In general, wild-type species tend to be much more stress-tolerant than the varieties that we have developed by breeding in the last 10,000 years.”

Checkbiotech learned that the strategy developed by Dr. Blumwald and his team can be applied to all crop plants, which is good news for farmers all over the world and will benefit them all.

Meanwhile, the team is continuing their research to address the questions concerning quality and taste of fruits and have obtained interesting preliminary results indicating no major shift in metabolite profiles of the transgenic fruit compared with wild-type plants.

When asked if he is confident about the feasibility and economic viability of growing transgenic crops on a large scale, Dr. Blumwald emphatically replied, “Absolutely! That is what we are working towards.”

Tanuja Rohatgi is a Science Writer for Chechbiotech at Basel, Switzerland .

Source:
Delayed leaf senescence induces extreme drought tolerance in a flowering plant.
Rosa M. Rivero, Mikiko Kojima, Amira Gepstein, Hitoshi Sakakibara, Ron Mittler, Shimon Gepstein, and Eduardo Blumwald
PNAS. Dec 4, 2007. 104(49): 19631-19636.

ABSTRACT

Drought, the most prominent threat to agricultural production worldwide, accelerates leaf senescence, leading to a decrease in canopy size, loss in photosynthesis and reduced yields. On the basis of the assumption that senescence is a type of cell death program that could be inappropriately activated during drought, we hypothesized that it may be possible to enhance drought tolerance by delaying drought-induced leaf senescence. We generated transgenic plants expressing an isopentenyltransferase gene driven by a stress- and maturation-induced promoter. Remarkably, the suppression of drought-induced leaf senescence resulted in outstanding drought tolerance as shown by, among other responses, vigorous growth after a long drought period that killed the control plants. The transgenic plants maintained high water contents and retained photosynthetic activity (albeit at a reduced level) during the drought. Moreover, the transgenic plants displayed minimal yield loss when watered with only 30% of the amount of water used under control conditions. The production of drought-tolerant crops able to grow under restricted water regimes without diminution of yield would minimize drought-related losses and ensure food production in water-limited lands.

 

 

RELATED NEWS RELEASE

New drought-tolerant plants offer hope for warming world

 

 

The news item on this page is copyright by the organization where it originated - Fair use notice

Other news from this source


Copyright © SeedQuest - All rights reserved