Articles
THE DEVELOPMENT OF REGENERATION AND TRANSFORMATION SYSTEMS FOR PEACH
These calli were originally derived from immature (40–50-day postbloom) peach embryos.
Plants have been regenerated from these long-term cultures but at low frequency.
High frequency shoot regeneration has been obtained from 70-day postbloom peach cotyledons on MS medium + vitamins with 7.5 μ M thidiazuron + 2.5 μ M indolebutyric acid.
Cotyledons were stored at 4°C for up to 90 days without loss in regeneration potential.
These techniques make regenerative peach cultures available for extended periods of time, reducing the need for re-isolation of immature embryos from young fruit.
Peach plants, leaf pieces, and embryogenic calli have been exposed in vitro to an engineered Agrobacterium tumefaciens binary vector carrying the NOS-NPTII-NOS chimeric gene on pGA472 and the vir and tumor-inducing genes (tms/tmr) on the helper plasmid pTiBo542 (kindly provided by G. An, Washington State University). Growth of calli on a medium containing kanamycin, but free of growth regulators, indicated transformation of all three tissue sources.
Southern analyses are being performed to confirm the stable incorporation of the kanamycin resistance gene (NPTII).
This work indicates that while regeneration and transformation technologies for peach require continued refinement, the use of these technologies, together with the identification and isolation of appropriate genes, may provide a feasible approach to genetic improvement of peaches, complimenting hybridization.
(Detailed results of these studies will be published elsewhere.)