Blue dye, in this cross-section of a maize cob, highlights the rice gene that controls T6P in the kernels’ phloem. Image: Rothamsted Research
Through the introduction of a rice gene, scientists have produced a maize plant that harvests more kernels per plant – even in periods of drought.
The rice gene expressed depresses levels of a natural chemical, trehalose 6 -phosphate (T6P), in the phloem of the transgenic maize plant. T6P is responsible for the distribution of sucrose in the plant.
Lowering levels of T6P in the phloem, an essential track in the plant’s transportation system, allows more sucrose to be channelled to the developing kernels of the plant. As a result of increased levels of sucrose in this area of the maize plant, more kernels are produced.
Drought is an increasing problem in countries such as Uganda. Image: Hannah Longhole
‘These structures are particularly sensitive to drought – female kernels will abort,’ said Matthew Paul, team leader and plant biochemist at Rothamsted Research, UK. ‘Keeping sucrose flowing within the structures prevents this abortion.’
The transatlantic team, from Rothamsted and biotechnology company Syngenta in the US, built on field tests published three years ago that demonstrated increased productivity of the same genetically-modified maize.
‘This is a first-in-its-kind study that shows the technology operating effectively both in the field and in the laboratory,’ said Paul.
Maize growing on world’s oldest experiment, Broadbalk field at Rothamsted Research. Image: Rothamsted Research
Drought is becoming an increasing problem for developing countries, where the economic and social impacts are most evident.
Maize, also known as corn, and other cereals are relied on heavily across these nations due to their low cost and high nutritional value, with rice, maize, and wheat used for 60% of the global food energy intake.
The results of these trials are promising, and the team believe this work could be transferred to wheat and rice plants, as well as other cereals, said Paul.
Russian researchers have developed new fertilisers based on nanopowders of transition metals. In field trials on agricultural crops, harvests increased by more than a quarter, compared with conventional fertilisers.
Iron, cobalt and copper affect a plant’s level of resistance to pests and diseases. These microelements are typically introduced into the soil as soluble salts, but rain and irrigation can wash them away, requiring further applications. They also have potential to disrupt local ecosystems as they pass into the groundwater.
An irrigation system in Idaho, US. Image: Jeroen Komen@Wikimedia Commons
The team, led by the National University of Science and Technology (NUST) in Moscow, has developed a group of fertilisers that are applied as a powder to plant seeds, without losses to the soil or water systems. In this way, ‘the future plant is provided with a supply of necessary microelements at the stage of seeding,’ reports Alexander Gusev, head of the project at NUST’s Department of Functional Nanosystems.
‘[It’s] a one-seed treatment by a product containing the essential microelements in nanoform. These particles of transition metals – iron, copper, cobalt – have a powerful stimulating effect on plant growth in the initial growth phase.’
Gusev reports improved field germination and increased yields of 20-25%.
The main difficulty was to produce a powder from the nanoparticles, which tended to quickly stick together as aggregates, says Gusev – a problem they solved by using organic stabilisers and then subjecting the colloidal solutions to ultrasonic processing.
Gusev now wants to discvover how the new fertiliser acts in different soils, and in relation to different plant cultures. Its environmental safety also needs to be evaluated before widespread use, he adds.
But Steve McGrath, head of sustainable agricultural sciences at Rothamsted Research, is sceptical. Plants are adapted to take up ionic forms of these microelements, not nanoparticles, he says. ‘Also, seeds do not take up much micronutrients. Roots do that, and depending on the crop and specific nutrient, most uptake is near to the growing ends of the root, and throughout the growing season, when the seed and nearby roots are long gone.’
Critics are skeptical of the efficacy of the new kind of fertiliser. Image: Pexels
If there is an effect on crop yield, he thinks it is more likely to be due to the early antifungal and antibacterial effects of nanoparticles. ‘They have a large and highly reactive surface area and if they are next to membranes of pathogens when they react they generate free radicals that disrupt those membranes. So, in a soil that is particularly disease-infected, there may be some protection at the early seedling stage.’