Table 2.
Further approaches applied to improve P. persica L. regeneration–transformation.
| Genotype | Explant | Route of Morphogenesis | Shoot Regeneration Rate a (%) | Transformation Method | Plasmid (Genes) | Selection Strategy (Agent) | Outcome/Comments | Main Advantage | Main Disadvantage |
|---|---|---|---|---|---|---|---|---|---|
| Assessed methodologies that involve peach juvenile tissues | |||||||||
| “O’Henry”, “Elegant Lady”, “Rich Lady”, “Venus” | Immature cotyledon | Somatic embryogenesis | 60.0 | Not assayed d | -- | -- | A similar regeneration procedure coupled with A. tumefaciens has previously succeed in the generation of transgenic peach plants [13]. | Consistent whole plant production. | Explants available for only a limited time each year (50 to 70 days post-bloom). |
| “Bailey”, “Guardian”, “Starlite” | Organogenesis | 80.0 | A. tumefaciens GV3101 | pVNFbin (nptII, gus) |
Negative: early or late (kanamycin) |
Selection failed. All surviving shoots were escapes. | Efficient adventitious regeneration. | Explants available for only a limited time each year (45 to 50 days post-bloom). | |
| “TruGold” | Mature hypocotyl slice | Organogenesis | 14.0 |
A. tumefaciens (EHA101, GV3101) |
pVNFbin (nptII, gus) |
Negative: early (paromomycin) |
Selection failed. All surviving shoots were escapes. | Explants available year-round (mature seeds can be stored at 4 °C for several years). | Plants regenerated from transformed tissues via organogenesis may be chimeras. |
| “Bailey” | 32.0 | A. tumefaciens EHA105 |
ipt-containing construct (ipt, gus) |
Positive: early (low-level TDZ) |
Selection failed. All regenerated shoots were escapes. | ||||
| “Nemaguard” | 43.0 | A. tumefaciens EHA105 | pBarGUS (bar, gus) |
Negative: early (BASTA) |
Selection failed. All surviving shoots were escapes. | ||||
| “Bailey” | Seed-derived internode | Organogenesis | 42.9 | A. tumefaciens EHA101 | pVNFbin (nptII, gus) |
Positive: early (paromomycin) |
All shoots died during selection. | Explants available year-round (mature seeds can be stored at 4 °C for several years). | Plants regenerated from transformed tissues via organogenesis may be chimeras. |
| Assessed methodologies that involve peach adult tissues (cultivars or rootstocks) | |||||||||
| “Hansen 536” b | Leaf from meristematic bulk | Somatic embryogenesis | 0 | Not assayed | -- | -- | -- | Explants available year-round. | Potential for somaclonal variation due to the use of a highly differentiated tissue such as leaf. |
| “GF677” b | Petal and anther | 0 | -- | Regeneration via SE reduces the formation of chimeras. | Explants must be tested at different developmental stages, which can influence SE. | ||||
| “EVD 1”, “EVD 2”, “EVD 3”, “EVD 44288”, “Redglobe”, “Redhaven”, “Coacalco-OP c”, “Rutgers Redleaf-OP”, “Sihung Chui Mi-OP”, “Nemaguard-OP”, “Indian Cling OP” | Leaf | Organogenesis | 0 (only root regeneration observed) | Not assayed d | -- | -- | -- | Explants available year-round. | Inefficient adventitious shoot regeneration protocol. |
| “Bailey-OP” | Axillary shoot | Organogenesis | 100.0 |
A. tumefaciens (GV3101, EHA105) |
pSGN (nptII, eGFP) |
Negative: early (kanamycin) |
Selection failed. All surviving shoots were escapes. | Consistent whole plant production. | Plants regenerated from transformed tissues via organogenesis may be chimeras. |
| Nodal explant | Organogenesis | 73.3 | A. tumefaciens EHA101 | pVNFbin (nptII, gus) |
Negative: early (paromomycin) |
Two chimerical shoot lines detected (1.7% transformation efficiency). | Explants available year-round. | Plants regenerated from transformed tissues via organogenesis may be chimeras. | |
| “UFO-3′, “Alice Bigi”, “Garnem” b | Meristematic bulk | Organogenesis | 25.0, 8.3, 91.6 (respectively) |
A. tumefaciens (C58, EHA105) |
pBin19-sgfp (nptII, GFP) |
Negative early (kanamycin) |
Transient transformation. | The explants are produced in a relatively short period of time (90 days). | Certain probability of somaclonal variation induced by increasing concentrations of cytokinins applied to the initial explant. |
| “Hansen 53”′ b | Meristematic bulk | Organogenesis | 80 | A. tumefaciens EHA105 | pK7WG2-ihp35S-PPV194::eGFP (nptII, gfp, PPV polyprotein hairpin) |
Negative: early or late (kanamycin) |
Stably transformed calli. | ||
a Shoot regeneration rate under non-selective conditions. b P. persica x P. amygdalus hybrids. c OP: Open-pollinated. d Transformation experiments were not performed in this case.