AMES, Iowa — Conventional approaches to plant genome editing still require transformation techniques that present roadblocks for many crops.
A new project supported by a two-year, $300,000 grant from the USDA Agriculture and Food Research Initiative, will explore the potential to employ viruses to overcome the usual tissue culture barriers that impede gene editing in sorghum and switchgrass.
The research is being led by Steve Whitham, a professor in plant pathology and microbiology at Iowa State University, along with co-investigators Maria Salas-Fernandez, associate professor in agronomy, and Shuizhang Fei, professor of horticulture.
Their grant is part of a $3.4 million multi-institution investment in 12 projects nationwide that are part of a USDA Ag Innovation through Gene Editing Initiative.
The Iowa State researchers plan to use plant viruses, such as Foxtail mosaic virus, as vehicles for delivering guide RNAs in sorghum and switchgrass. The guide RNAs are part of CRISPR gene editing systems that can direct changes in genetic sequences to modify the functions of genes. The goal is to create controlled techniques to introduce the guide RNA from compatible plant viruses into cells of the target plants, inducing desirable gene edits that can be inherited.
“We believe we can develop this new tool to simplify and accelerate gene editing applications in sorghum and switchgrass, which will enable more rapid progress in improving agricultural traits related to yield, stress and disease resistance and nutrient use efficiency,” said Whitham.
Sorghum is important for grain and forage production and both sorghum and switchgrass are important feedstocks for bioenergy production due to their ability to fix large amounts of carbon and convert it into biomass. Both species can be transformed by traditional gene-editing technologies, but successful transformation is restricted to only certain genotypes and the process is lengthy.
As a perennial crop, switchgrass is an especially time-consuming plant to breed using conventional technologies, said Fei. He foresees the research being used to enhance traits such as delayed flowering or increased tillering for more stems per plant, which could increase yields and improve economics for producers.
“Sorghum is also one of the most difficult crops to transform through conventional practices,” Salas-Fernandez said. “It is a big bottleneck for breeding. If we can succeed at this, heritable edits can be transferred to the next generation, which would avoid a lot of steps in what is now a very long process and make sorghum more competitive as a biofuel.”
Project leader Whitham emphasized the ‘proof of concept’ nature of the new grant.
“This support is for technology development to see if it can work. We’re optimistic and have a good start, but we have a lot of work ahead to develop and demonstrate this as a practical tool.”
— Iowa State University College of Agriculture and Life Sciences
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