Pabitra Joshi’s deep, DNA-level dive into wheat traits positions the University of Idaho’s breeding program to release more varieties that resist dwarf and common bunt.

The recent UI doctoral graduate used advanced breeding and mapping techniques to make key trait-related discoveries that figure to influence future cultivar development.

Joshi also sped up the breeding process.

She found two quantitative trait loci — DNA regions close to a specific gene that influence the variation of a trait in a population of organisms — associated with common bunt and dwarf bunt resistance in a particular wheat chromosome. She developed primers to check cultivars for presence of the gene/loci.

A mapping population helps crop breeders identify locations of genes that control specific traits, which they map for use in marker-assisted selection, according to UI.

Joshi used a mapping population developed by crossing resistant hard white winter wheat UI Silver with susceptible line Shaan 89150.

Developing a new cultivar through conventional breeding can take 14 to 15 years from the first cross to the variety’s release, she said.

Joshi used double haploid breeding instead.

“With double haploid breeding techniques, we try to fix the genotype of the line by doubling the chromosome,” she said. The development cycle can drop to three to five years.

About 135 double haploid lines were developed from the crossing. Most will show resistance because the gene is more dominant, but some will show partial resistance or some susceptibility, Joshi said.

She expects one or two to be developed as cultivars.

“They’re selected based on not just resistance, but the full package,” Joshi said. Yield, adaptability to certain environments, and end-use quality are among considerations.

She worked under adviser Jianli Chen, endowed professor of wheat breeding based at the UI Aberdeen Research and Extension Center. The project was supported by a USDA National Institute of Food and Agriculture food research initiative grant.

Chen will use the QTLs Joshi located, and other markers associated with resistance to the diseases, in screening wheat breeding lines, according to UI.

For her dissertation, accepted for publication in Theoretical and Applied Genetics, Joshi screened more than 170 winter wheat lines, developed by UI and by Washington State and Utah State universities, for the presence of the two QTLs she located.

Diseases make resurgence

Dwarf and common bunt were big threats to wheat until the 1950s advent of chemical fungicides, but in recent years the diseases have made a resurgence, according to UI.

Climate change and the increased popularity of organic agriculture are key reasons the diseases are increasingly important, Joshi said.

“We need more stable and sustainable solutions,” she said.

Joshi also worked on the Wheat Coordinated Agriculture Project led by the University of California, Davis. The work, which involved 20 doctoral students and 41 breeders, uses technology such as high-throughput phenotyping to breed wheat suited to climate change, according to UI.

Joshi, who became a licensed drone pilot, flew drones over breeding fields in Aberdeen, analyzed the imagery and used it in trait prediction models.

She is from Nepal. Her interest in agriculture began at home, “watching my family work in our home garden,” she said.

“Growing up in Nepal, where agriculture is a way of life for most people, I developed a deep appreciation for farming and its role in supporting families and communities.” Joshi said.

Name: Pabitra Joshi

Age: 29

Title: Recently hired USDA Agricultural Research Service postdoctoral researcher, Geneva, N.Y.

Education: Ph.D., plant science, University of Idaho, December 2024, B.S., agriculture, Agriculture and Forestry University, Nepal.

Hometown: Kanchanpur, Nepal

Family: Single

Hobbies: Cooking, hiking, learning.