Gene-Editing Crops Regenerate Much Faster, With Applications in Citrus, Strawberries and Poplar

A technology that speeds up the regeneration of gene-edited crops has been developed. It is expected to accelerate the breeding of perennial crops such as citrus, strawberries and poplar.

According to AgriLife Sciences on the 11th (local time), a joint research team from Texas A&M AgriLife Research, the University of Maryland and the U.S. Department of Agriculture (USDA) developed CRISPR-Combo, a technology that induces gene editing and plant regeneration simultaneously. The findings were published in the journal Nature Communications.

The technology edits a gene of interest while also activating the plant’s own morphogenic genes. Morphogenic genes regulate the process by which cells develop into roots, stems and complete plants. Rather than adding growth-promoting genes from outside, the method increases the expression of genes already present in the plant genome.

The researchers said regeneration is the biggest obstacle to the commercialization of gene-editing technology. “We showed that the plant’s own genes can be used to induce faster and more reliable regeneration,” said Kranti Mandadi, a professor in the Department of Plant Pathology and Microbiology at Texas A&M University. “This offers practical potential for perennial crops such as citrus, which have been difficult to work with in the laboratory.”

Perennial crops such as citrus and poplar can take years to complete a single breeding cycle, while high-value fruit and nut crops are particularly difficult to transform and regenerate in the laboratory. The researchers said activating the plant’s own regeneration genes, without relying on external hormones or additional genetic material, offers a simpler and more scalable approach.

The researchers first screened candidate genes using the rapid “hairy root” system developed by AgriLife Research. The system induces root formation in cuttings without the lengthy process of regenerating a complete plant.

In potatoes, the team tested 17 candidate genes and identified four that promoted root formation. Three of these also improved stem regeneration, raising regeneration efficiency to 45~70%. The control group was about 30~35%, said Manikandan Ramasamy, a research associate at AgriLife Research and the study’s lead author.

In citrus, which is known to be difficult to transform and regenerate, five of 10 candidate genes significantly increased root formation. Under laboratory conditions, all five genes raised stem regeneration efficiency to more than 80%, compared with less than 60% in the control group.

The researchers also tested simultaneous activation of two morphogenic genes in wild strawberries and poplar. In strawberries, simultaneous activation of specific genes shortened the time needed to produce a complete gene-edited plant by more than a month compared with the conventional method.

The effect was greater in poplar. When the genes were activated together, stems regenerated within a month, without the external plant hormones typically required for tissue culture. Poplar lines in which both genes were activated had the highest proportion of edited cells, grew into larger plants with greater biomass in the greenhouse and showed no obvious abnormalities.

The study was funded primarily by the Foundation for Food & Agriculture Research’s “Genotype-Independent Fertile Plant Regeneration” program, with additional support from the National Science Foundation, the USDA National Institute of Food and Agriculture, the U.S. Department of Energy and others.