Green Design

Manipulating Plant Growth Hormones Key for Biofuel Future

Auxin is a powerful plant growth hormone that tells plants how to grow, where to lay down roots, how to make tissues, and how to respond to light and gravity. Knowing how to manipulate auxin could have enormous implications for the production of biofuel - making plants grow faster and better.

A special protein, the ICR1, controls the way auxin moves throughout a plant affecting its development. Professor Shaul Yalovsky of Tel Aviv University's Molecular Biology and Ecology of Plants Department has found that when this protein is genetically engineered into valuable biofuel crops such as corn, sugarcane, or experimentals like switchgrass, farmers can expect to get a far larger yield than what they harvest today.

"We've found a mechanism that helps the shoot and root talk to each other," says Yalovsky. "Somehow both parts of the plant need to speak to each other to say: 'Hey down there, I'm up here and there's lots of sun,' or 'I'm down here in the roots and it's too dry." The plant's shoots need to respond to its environment. We've discovered the mechanism that helps auxin do its job."

The ICR1 protein that Yalovsky has isolated works together with a group of proteins called ROPs, which his lab also isolated in previous research. Together, they manipulate the composition and vascular tissues of plant cell walls. The researchers found specifically that ICR1 can be manipulated and, as a consequence, influence auxin distribution in plants. Plant scientists now have a tool that allows breeders to grow certain plant organs of choice, with the possibility of manipulating plant cell wall composition — the kinds of tissues needed in making biofuel.


Plant tissue is made of cells engulfed in a tough cell wall that helps it retain shape and rigidity. It is composed of cellulose, a polysaccharide, and lignin, which is the woody material in a plant. Current methods for removing the unwanted lignin in the cell wall — which must be removed to produce biofuel — amounts to about a 50% loss cellulosic material which could be used for biofuel.

Ideally crop growers want to maximize the amount of cellulose in the plant, which can be broken down to make sugar for ethanol. The new system found in proteins and developed at Tel Aviv University has the potential to increase crop yield and make fuel production more cost-effective. Yalovsky says his approach could mean less lignin, more cellulose and ultimately more biofuel.

(Tel Aviv University)