First-generation genome editing in potato using hairy root transformation.

Area of Science:

• Plant Biotechnology
• Crop Improvement
• Molecular Genetics

Background:

• Genetic transformation is key to crop improvement, but many species, including vital potato relatives, are recalcitrant to standard methods.
• Agrobacterium rhizogenes-mediated hairy root transformation offers an accelerated route to transgenic material but is typically limited to root clone analysis.

Purpose of the Study:

• To establish a robust Agrobacterium rhizogenes-mediated transformation system for the wild potato relative Solanum chacoense.
• To apply CRISPR/Cas9 genome editing in hairy root clones and assess mutation stability and chimerism in regenerated plants.

Main Methods:

• Tested various Agrobacterium rhizogenes strains for transformation efficiency in Solanum chacoense.
• Generated transgenic hairy root clones expressing GUS marker and CRISPR/Cas9 reagents targeting the PHYTOENE DESATURASE (StPDS) gene.
• Regenerated whole plants from edited hairy roots and analyzed mutations in regenerated lines and progeny.

Main Results:

• Agrobacterium rhizogenes strain MSU440 successfully generated transgenic hairy roots capable of regeneration.
• CRISPR/Cas9 reagents induced targeted mutations in 64%-98% of hairy root clones with low chimerism (14%-30%).
• Stable mutations were maintained in 38% of regenerated lines and showed germ-line transmission.

Conclusions:

• Agrobacterium rhizogenes transformation provides a novel, accelerated method for genome editing in previously recalcitrant potato genotypes.
• This approach broadens the scope of plant species amenable to genetic modification and reduces chimerism in edited lines.
• The system facilitates rapid generation and propagation of edited materials for accelerated crop breeding programs.