Tissue Culture & Micropropagation
⭐ Plant Tissue Culture Pathways
5 Parameters
In Vitro Plant Regeneration: Organogenesis vs Somatic Embryogenesis
Comparative matrix of vascular continuity, polarity establishment, hormone ratios, and synthetic seed encapsulation.
| Feature | Organogenesis (Shoot / Root Regeneration) | Somatic Embryogenesis (Embryo Formation) |
|---|---|---|
| Developmental Polarity | Unipolar structure (forms either a shoot bud or a root primordium independently) | Bipolar structure (possesses both shoot apex and root pole simultaneously) |
| Vascular Connection to Explant | Direct vascular continuity with mother explant tissue / callus | Completely isolated vascular system (no vascular connection to parent callus tissue) |
| Hormonal Trigger (Auxin:Cytokinin) | High Cytokinin:Auxin induces shoots; High Auxin:Cytokinin induces roots | High 2,4-D (synthetic auxin) triggers induction; withdrawal of 2,4-D triggers maturation |
| Artificial / Synthetic Seed Utility | Cannot produce true synthetic seeds directly | IDEAL (somatic embryos encapsulated in sodium alginate beads form artificial seeds) |
| Secondary Regeneration Steps | Requires two steps: First shoot induction media, then transfer to rooting media | Single coordinated developmental program recapitulating zygotic embryogenesis |
Regeneration Polarity & Connection
Organogenesis
Polarity: Unipolar (Shoot OR Root)
Vascular Continuity: YES
Synseed Capable: No
Somatic Embryogenesis
Polarity: Bipolar (Shoot AND Root)
Vascular Continuity: NO (Independent)
Synseed Capable: YES
Plant Transformation Methods
⭐ Transgenic Plant Methods
5 Parameters
Plant Transformation: Agrobacterium-Mediated vs Biolistics (Gene Gun)
Comparative matrix of biological vs physical delivery, monocot vs dicot host range, copy number integration, and gene silencing risk.
| Parameter | Agrobacterium tumefaciens (Biological) | Biolistics / Particle Bombardment (Physical) |
|---|---|---|
| Delivery Mechanism | Natural Type IV secretion system transferring T-DNA delimited by 25 bp borders | Physical acceleration of gold/tungsten microprojectiles coated with DNA using pressurized helium |
| Host Range Preference | Historically excellent for Dicots; requires specialized acetosyringone for Monocots | Universal (no biological host barrier; transforms any monocot, dicot, organelle, or algae) |
| Inserted Copy Number | Low copy number (typically 1–2 clean intact T-DNA copies per genome) | High copy number with frequent tandem repeats and fragmented rearrangements |
| Gene Silencing Risk | Low risk (clean single-copy integration reduces epigenetic silencing) | High risk (multiple concatemer repeats trigger homology-dependent gene silencing) |
| Organelle (Plastid) Transformation | Cannot transform chloroplasts (T-DNA targeted exclusively to nucleus) | Capable of transplastomic transformation (delivers DNA into chloroplasts) |
Transformation Method Comparison
Key Point
Method: Agrobacterium
Copy Number: 1 - 2 (Clean)
Host Range: Mainly Dicots
Organelle Capable: No (Nuclear only)
Key Point
Method: Biolistics
Copy Number: High (Rearranged)
Host Range: Universal (Monocots/Dicots)
Organelle Capable: YES (Plastids)
