Crop spray designed to combat drought

KINGSTON, Ont. — Chemicals are used for nearly everything in farming, from killing flea beetles in canola to controlling wild oats in wheat or defeating white mould on soybeans.

Such products are usually de-signed to fight a specific problem, but a Chinese plant science institute has developed a chemistry to tackle a more universal challenge: drought.

“There have been various chemicals … that supposedly can protect plants from drought. We’ve compared ours to pretty much everything we could find on the market. This has much higher (efficacy),” said Jian-Kang Zhu, of the Shanghai Centre for Plant Stress Biology and a professor of horticulture at Purdue University.

Zhu, who spoke at Plant Biotech 2016, which was held in Kingston June 18-19, said his team in Shanghai has been working on the spray for five years. The researchers published a paper in 2013 on the first version of the chemical in the journal Cell Research.

Scientists have since developed a second generation of the chemical, which is much more effective than the original formulation.

“The chemical we initially obtained, you had to spray repeatedly,” Zhu said. “The newer chemical, it’s more potent. One spray does a lot.”

The paper said the chemical mimics the properties of abscisic acid (ABA), a hormone that helps plants combat drought.

“A single small molecule (the chemical) … can activate multiple ABA receptors and protect plants from water loss and drought stress,” the scientists wrote.

Zhu said the chemical was not an accidental discovery.

“This is the result of decades of work. Not just my own … to understand the ABA pathway and how ABA receptors work and how the downstream signaling pathway works,” he said.

“With this knowledge, we were able to design a screen to look for chemicals that bind (to) the receptor.”

Zhu showed photos of Arabidopsis plants that had been treated with the chemical, a control group and a group in which plants had been modified to over-express ABA receptors.

The control group was dead or dying after a few weeks without water, but the plants sprayed with the chemical were still green.

“What this chemical does is it closes (plant) stomata so there is very little water loss … and protects the plants from dehydration damage,” he said.

“It’s almost like desert plants. The soil water content is so low, they’ve been without water for more than a week and they’re still surviving…. If you combine them with genetics, the over-expression of ABA receptors, you do even better.”

The Shanghai research centre and Zhu have a patent pending on the technology, but they do not have a corporate partner.

Zhu said they have done field research on the drought spray, but more testing and positive results are needed to attract investment.

Jeff Habben, senior research manager for trait discovery with DuPont Pioneer USA, said the spray is an interesting concept but taking such a product from the lab to commercialization can be challenging.

“ABA is a known hormone that’s involved in drought tolerance,” he said.

“If we can manipulate that pathway somehow, that’s great.”

However, drought tolerance is a tricky business. Plant mechanisms that turn on when conditions are dry also tend to limit plant growth and yield.

“ABA is involved in defense mechanisms … but also affects growth,” Habben said. “Finding that balance is really tough.”

Manitoba reporter Robert Arnason recently learned about the latest advancesin agricultural biotechnology while attending the Plant Biotech 2016 conference in Kingston, Ont. For more stories from the conference, see pages 14, 15.

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