New insights into natural rubber biosynthesis from rubber-deficient lettuce mutants expressing goldenrod or guayule cis-prenyltransferase.

Lettuce produces natural rubber (NR) with an average M of > 1 million Da in laticifers, similar to NR from rubber trees. As lettuce is an annual, self-pollinating, and easily transformable plant, it is an excellent model for molecular genetic studies of NR biosynthesis. CRISPR/Cas9 mutagenesis was optimized using lettuce hairy roots, and NR-deficient lettuce was generated via bi-allelic mutations in cis-prenyltransferase (CPT).