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Gene editing to enhance colour and flavour in wheat

Researchers in the US and UK have edited multiple wheat genes to reduce the polyphenol oxidase activities in wheat grain.
Photo: GRDC

A research partnership between Colorado State University in the US and the UK-based Rothamsted Research has successfully edited multiple wheat genes to reduce the polyphenol oxidase (PPO) activities in wheat grain.

PPO activity helps wheat plants to better resist biotic stresses. However, it also causes undesirable effects such as discolouration and unpleasant flavours during post-harvest. Unpleasant flavours and the discolouration of flour, dough and other end-use products of wheat reduce its market value. The researchers edited all seven PPO1 and PPO2 genes in wheat using the gene-editing tool CRISPR-Cas9.

According to the findings published in the journal Frontiers in Plant Science, the research accelerates a more cost-effective approach to improving crops and presents an opportunity to develop varieties of wheat with reduced PPO activities and increased market value.

First GM fruit submitted for commercial approval

In an Australian first, a genetically modified (GM) banana developed by researchers at the Queensland University of Technology is on track to become the country’s first GM fruit approved for commercial cultivation. The banana, called QCAV-4, is modified to be resistant to the strain tropical race 4 (TR4) of the fungal disease Fusarium wilt, also known as Panama disease.

Bananas are a major food crop globally and are grown and consumed in more than 100 countries. In developing countries, they are the fourth-most-important food crop after rice, wheat and maize. Most of Australia’s bananas are grown in Queensland, with the industry there worth about $580 million.

Without a known pesticide or method of control, Fusarium wilt can spread rapidly and remain in the soil for more than 50 years. The disease invades the roots of banana plants, limiting the supply of water and nutrients, affecting yields and eventually killing the plant. In 2015, TR4 made its way to the Tully Valley in Queensland, but intensive quarantine measures were put in place to prevent the spread of the disease across the broader banana industry – a measure that has so far been successful.

The Queensland University of Technology has also applied to Australia’s food regulator, Food Standards Australia New Zealand, for the fruit to be allowed for sale as food.

US expands GM crop adoption

GM varieties of maize, cotton and soybeans represent almost 100 per cent of their respective national commodity crops, according to an update released by the US Department of Agriculture’s Economic Research Service (ERS).

Commercial GM crops were first planted in the US in 1996, and their success has seen them become the dominant options on offer for growers. The most widely used varieties are herbicide tolerant, insect resistant, or a combination of both.

According to the ERS, the 2023 trends include:

  • more than 90 per cent of US maize, cotton (upland) and soybeans are GM varieties;
  • the herbicide-tolerant soybean acreage was 95 per cent in 2023, compared to 94 per cent for herbicide-tolerant cotton and 91 per cent for herbicide-tolerant maize;
  • the insect-resistant (Bt) maize acreage reached 85 per cent in 2023, compared to 89 per cent for Bt cotton; and
  • approximately 86 per cent of the cotton crop and 82 per cent of the maize crop are varieties that stack both herbicide tolerance and insect resistance.

GM cowpeas approved in Ghana

A GM cowpea variety developed to be resistant to the Maruca pod borer by the Savanna Agricultural Research Institute (SARI) has become Ghana’s first-ever GM crop. According to the developers, the new cowpea, set to be available to growers in Ghana by the end of 2023, will increase yields by nearly 300 per cent.

The Maruca pod borer is an insect pest that causes losses of up to 50 per cent of cowpea pods in the country. It can only be controlled by spraying insecticide – usually about eight times over a three-month period.

“We have done a lot of assessment on the cowpea that we’re releasing in terms of its impact on the environment and on human health, and there’s a lot of data and information to show that it is as safe as the conventional one and even much safer because insecticides normally have a lot of health implications when people eat cowpeas sold in the market,” says Jerry Nboyine, a senior SARI research scientist in Ghana.

Australian researchers have been very involved in transferring knowledge to develop GM cowpeas in Africa, including CSIRO’s Dr TJ Higgins, a previous recipient of GRDC’s Seed of Light award.

CSIRO was approached by the African Agricultural Technology Foundation to develop a system for genetically engineering cowpeas. The team was able to develop several pod borer-resistant cowpea lines, and field trials to test agronomic performance and insect resistance have been carried out over several years in Puerto Rico, Nigeria, Burkina Faso, Ghana and Malawi.

The cowpea plant breeders in each of these countries have crossed the Bt gene into grower-preferred varieties and evaluated their acceptability and suitability for local environments.

The GM insect-resistant cowpea is also approved for food, feed and cultivation in Nigeria.


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