Biostimulant and bioherbicide tech targets yield gains

A biostimulant that can boost yields by up to 20% and a bioherbicide with insulin-like properties that fools plants into shutting down are two high-tech solutions being developed for arable farmers.

Bristol-based startup Glaia has developed a way to improve the efficiency of photosynthesis in plants. With a commercial product already available in strawberries, the firm is working on another product for cereals, including wheat.

Photosynthesis is, perhaps surprisingly, inefficient, with only 1% of the sunlight plants receive being converted into biomass. But Glaia, spun out of research conducted at the University of Bristol, found that naturally occurring carbon materials could directly target photosynthesis in plants to improve their ability to convert sunlight into biomass.

See also: Soil tech solutions target compaction and farm energy generation

Plants can use only a limited amount of sunlight they receive and the process of photosynthesis in the chloroplast is inefficient, explains Glaia chief scientific officer Dr Imke Sittel.

“Our light-use-efficiency technology uses tiny carbon-based particles called carbon dots to help plants make better use of sunlight. These increase the flow of electrons, which means the plant produces more energy and sugars through photosynthesis, leading to stronger growth and higher yields.”

The improvement in photosynthetic output has increased yields by up to 20% in strawberries and lettuce, and by 8% in tomatoes. Initial trials in wheat have also shown an 8% yield uplift, Imke says. “We’re now developing a product specifically for cereals.”

A liquid formulation, the product can be applied as a foliar spray, meaning no changes to existing practices. In wheat, applications are likely to coincide with spring fungicide applications when photosynthesis will be at its peak. More research is under way to fine-tune use, with the company searching for growers to test the product next spring.

But with regulatory pathways for biostimulants in the UK relatively straightforward, the cereal product could be available within a couple of years, Imke suggests, to follow the already commercially available berry product.

Bioherbicides with insulin-like properties

Peptides – short chains of amino acids – with specific sequences could become next-generation herbicides, research at the University of Cambridge’s Sainsbury Laboratory suggests.

In humans, peptides act as messengers in the body, regulating many biological functions. A classic example is insulin, which regulates blood sugar levels, explains researcher Dr Nadia Radzman.

“It is very effective, and very precise. If we change the [amino acid] sequence of insulin, it doesn’t work. That’s the level of precision and efficacy we want to bring to agriculture.”

Nadia’s PhD research found a peptide that would fool plants into thinking they were starved of nitrogen, even when there was plenty available. Her current research is using a similar principle for weed control.

“With the bioherbicide I’m developing, I’m fooling the plants to think they’re very stressed, so they wilt and yellow because they think they’re in high drought conditions, and this extreme stress kills the plant.”

The peptide is not toxic to the plant, she stresses. “It’s using the stress response of the plant against itself and that should mean the selection pressure [for resistance] to evolve is much less likely.”

To make the technology selective, Nadia needs to co-deliver the peptide with another chemical to protect the crop. A RNAi spray, it is very specific to the crop type, but will protect any variety from being killed by the bioherbicide.

“It makes the crop blind to the bioherbicide and at the same time also buffers the crop to the stress the peptide bioherbicide is causing, so you have two benefits in one.”

The principle is not unlike the herbicide-tolerant systems already used in agriculture, such as Roundup Ready genetically modified (GM) crops or Conviso Smart system used in a sugar beet.

“But GM crops are very dependent on the variety or type of crop, whereas this system, because it is a spray, will work on any variety or crop,” Nadia says.

The first bioherbicides using this approach are likely to be for weeds that are difficult to control with chemicals, such as glyphosate-resistant weeds, in markets such as Brazil and the US due to easier registration pathways. But in the longer term, UK and European markets with difficult grassweeds, such as blackgrass and Italian ryegrass, will be a target.