Solanum lycopersicum (Tomato) Transformation

Tomato genotype is the primary determinant of transformation efficiency. Model cultivars such as Micro-Tom, Moneymaker, and Ailsa Craig possess well-established tissue culture protocols and strong regeneration capacity, typically yielding 10 or more independent T0 positive plants within three to four months. In contrast, commercial processing lines or heirloom landraces may require extended regeneration periods and customized hormonal regimes. For CRISPR/Cas9-mediated modification, protoplast isolation efficiency and DNA repair pathway preferences also vary by genetic background, influencing both mutation rates and off-target potential. We therefore conduct feasibility assessments before project initiation and, when necessary, perform small-scale pilot studies to optimize strain, vector, and selection parameters for each specific cultivar.

For standard transformation projects, the interval from vector confirmation to T0 plantlet acclimatization typically spans three to five months, depending on genotype, selection marker, and regeneration efficiency. After transfer to the greenhouse, T0 plants undergo vegetative growth and flowering; self-pollination or crossing to produce T1 seeds generally requires an additional three to four months. Consequently, the complete cycle from vector delivery to T1 seed harvest usually falls between six and nine months. CRISPR editing projects requiring mutation characterization, segregation of transgene-free lines, or homozygous plant recovery may extend to ten or twelve months. We outline clear milestones at the proposal stage and provide regular progress updates throughout.

Yes. In addition to maintaining in-house stocks of standard model cultivars such as Micro-Tom, M82, and Moneymaker, we accept client-supplied proprietary or heirloom germplasm. For these materials, we first evaluate seed sterility, germination rate, and explant regeneration capacity, then adjust Agrobacterium infection, co-culture, and selection conditions to match the line-specific physiology. It is important to note that certain commercial hybrids or genetically complex accessions may exhibit lower transformation competence. In such cases, we recommend initiating a pilot study to assess feasibility and refine the protocol before committing to full-scale production, thereby minimizing risk and controlling overall project cost.

Transgene-free edited tomato lines are generated primarily through three strategies: direct delivery of pre-assembled Cas9-sgRNA ribonucleoprotein complexes into protoplasts; transient expression of CRISPR plasmids that do not integrate into the genome; or grafting-assisted DNA-free genome editing systems. Once T0 edited plants are recovered, we detect target-site mutations by PCR amplicon sequencing and simultaneously screen for residual Cas9 and selection marker sequences using locus-specific primers. For T1 progeny, segregation analysis confirms the stability of the edit across generations. We provide comprehensive genotyping reports and raw sequencing data to verify that delivered lines meet transgene-free standards.

Cotyledons and hypocotyls from 7- to 10-day-old aseptic seedlings are the preferred explant sources for Agrobacterium-mediated tomato transformation. At this developmental window, cells retain peak dedifferentiation capacity and respond vigorously to cytokinin-driven shoot induction. Cotyledonary segments provide a broad infection surface and produce abundant callus at wound margins, while hypocotyl segments often yield more organized shoot meristems. Older tissues or mature leaf discs exhibit markedly lower competence due to progressive lignification and reduced mitotic activity. We maintain standardized germination schedules for each genotype to ensure explants are harvested at optimal physiological receptivity, thereby maximizing the recovery of independent transformation events and minimizing experimental variability.

Chimerism is a recognized challenge in tomato organogenesis because adventitious shoots can arise from multicellular primordia containing both transformed and non-transformed cells. To address this, we apply stringent antibiotic selection during early regeneration and restrict shoot harvesting to discrete, physically separated callus clusters rather than bulk tissue masses. Each recovered T0 plant undergoes molecular screening of multiple independent leaf samples using locus-specific PCR; for editing projects, amplicon sequencing across the target region is performed on distinct tissue samples. Plants exhibiting uniform mutation patterns or consistent transgene signals across all tested tissues are classified as non-chimeric and advanced for downstream molecular characterization, seed production, or phenotypic analysis.

Stable transgenic lines integrate exogenous DNA cassettes—often including selectable markers and vector backbone sequences—that must be tracked and managed through subsequent generations. In contrast, CRISPR-edited lines may carry only the desired mutation without retaining foreign DNA, particularly when DNA-free ribonucleoprotein delivery or transgene-free segregation strategies are employed. For breeding programs, edited lines frequently offer a streamlined regulatory path in many jurisdictions and eliminate the need for marker-assisted backcrossing to remove transgenes. We provide comprehensive genotyping reports for every delivered line, including zygosity assessment and transgene presence or absence data, enabling clients to select the most appropriate material for either fundamental research or pre-breeding applications.