Zhang and Team Land $618K Grant to Improve Bread Wheat

Key advances made by scientists in the UC Davis Small Grains Breeding Program already have pointed a path to wheat that is more nutritious, more plentiful and more profitable for farmers. Now, that work will be boosted by a $618,000 grant from the United States Department of Agriculture.

The latest project is led by Xiaofei Zhang, an assistant professor in the Department of Plant Sciences and leader of the breeding program. Zhang and team aim to produce wheat that needs fewer inputs such as water and fertilizer, yet still produces nutritious grain at high volumes, and reliably. 

“Farmers need varieties that perform when water and other inputs are limited,” Zhang said. “This work is about delivering more stable yields and better grain quality under real-world conditions.”

Their focus is on wheat grown to bake bread – in particular, hard red spring wheat. New varieties Zhang and team develop will be made available to breeding programs in the U.S. as they share their results and the seeds they produce with other scientists and with farmers.

The researchers are building on the breakthrough that sparked the Green Revolution of the 1960s: The discovery of genes that make wheat and other staples grow short meant the plant could redirect its energy from growing tall to growing more seeds. In the subsequent decades, cereal production roughly doubled.

“Wheat breeding has relied on the same dwarfing genes for more than 50 years,” Zhang said. “Those genes worked extremely well in high-input systems, but agriculture is changing. Our goal is to develop varieties that maintain yield under water-limited and lower-input conditions.”

In 2023, Jorge Dubcovsky – long-time leader of the Small Grains Breeding Program – and his team discovered a different wheat gene that controls the height of plants. They called it PLATZ1. In addition, the gene shows potential to maintain or improve yield, Zhang said.

In this new project, the team will take PLATZ1 and another gene – both of them found in some varieties of wheat – and breed them into commercially grown varieties. 

Then, they will test the resulting plants in the field to see how the genes affect height, yield, drought tolerance, grain quality and protein content when grown in different conditions. Those include both irrigated and dry-land farming, and different levels of fertilizer.

They’ll use drones and more traditional methods to collect detailed crop information, such as how tall and big the plants get and how they respond to different levels of irrigation. Students will help: This project also will train the next generation of scientists in modern breeding techniques.

The three-year-project starts this month and is funded through the USDA’s National Institute of Food and Agriculture.

Advancing Green Revolution 2.0

The Green Revolution doubled wheat production by breeding plants that are short. The key “dwarfing” gene in wheat is called RHT1, for “reduced height,” and it limits the plant’s response to a naturally occurring growth hormone, gibberellin.

But the Green Revolution genes have drawbacks: Seedlings have trouble emerging on land that is not well-irrigated, so they produce poorly in warm, dry environments. In addition, dwarf plants can have lower amounts of some minerals that are important for people’s health. And, although the shorter plant produces more grains, individual grains can weigh less when the plant suffers stress. Plants also can be more susceptible to pests.

Zhang and team will eliminate the RHT1 dwarfing genes and replace them with PLATZ1 and another dwarfing gene, AP2L2. These genes respond to gibberellin in a way that keeps the plant short but overcomes other problems. The researchers will use both traditional breeding methods and CRISPR gene editing.

“We are not just making wheat shorter,” Xiaofei said. “We are redesigning how the plant grows, so it can emerge better from deep planting, build more biomass and sustain grain filling under stress.”