Tissue culture regeneration from

Kakimoto [20] used activational tagging to identify cytokinin independent or cki mutants. Cki mutants were selected in a tissue culture regeneration scheme as mutants that produced green calli from explanted hypocotyls in the absence of added cytokinin. Five... 

Figure 2. RNA blot analysis of jojoba elongase condensing enzyme gene expression in transgenic alfalfa. Total RNAs ( 15 gg) were separated on a formaldehyde gel, transferred onto a nylon membrane and hybridized with P-labeled jojoba condensing enzyme cDNA. RNA from vector transformed and nontransformed tissue culture-regenerated plants were used as control.

Plastid transformation is highly dependent on the tissue culture process because it enables copies of the wild-type plastid genome to be selectively eliminated before plant regeneration (Maliga, 2003). However, many of the crop species regenerated in this way turn out to be sterile, a consequence of plant regeneration from tissue culture. As mentioned earlier, the transformation of Arabidopsis, tomato, potato, rice, and rape seed oil has been achieved at very low efficiencies, and the resulting transformants... 

Witrzens, B., Scowcroft, W.R., Downes, R.W., and Larkin, P.J., Tissue culture and plant regeneration from sunflower (Helianthus annuus) and interspecific hybrids (H. tuberosus X H. armuus), Plant Cell Tiss. Organ Cult., 13, 61-76, 1988. 

Pugliesi, C., Cacconi, F., Mandolfo, A., and Baroncelli, S., Plant regeneration and genetic variability from tissue cultures of sunflowers (Helianthus annuus L.), Plant Breeding, 106, 114-121, 1991. 

Figure 9. Somatic cell selection for herbicide resistance. Bottom left, a flask of alfalfa cells in suspension. Top left, addition of herbicide to the cells. Center, cells plated onto solid medium containing herbicide a resistant callus growing on herbicide-containing medium. Top right, resistant plantlets regenerating. Bottom right, tolerant plants selected from tissue culture growing in the field after being sprayed with the herbicide.

Figure 18. Tissue culture sequence to obtain transformed petunia plants expressing a foreign gene, kanamycin resistance. The petri plate at the bottom contains two calli. The callus not forming shoots received the "long transfer", and the shoot-forming callus, the "short transfer". The "short transfer" shoots are removed from the callus and rooted in the container in the center. The rooted plant is transferred to the greenhouse. The leaves of the regenerated plant express the foreign gene.

The procedure by which imidazolinone-resistant corn was selected has been described previously, and will be reviewed only briefly here (7). The program was directed by Dr. Paul Anderson of Molecular Genetics Incorporated (MGI), under a contract with American Cyanamid. Scientists at MGI were among the first to regenerate corn routinely from tissue culture. 

Tissue culture of saffron including somatic embryogenesis and shoot regeneration has been first reported by George et al [105], Induction of crocin, crocetin, picrocrocin and safranal synthesis in callus cultures of saffron-Oocws sativus L has been reported by Visvanath et al [106]. Callus cultures were obtained from floral buds on Murashige and Skoog s medium supplemented with 3% sucrose, 2,4-dichlorophenoxy acetic acid... 

Auxin and cytokinin are essential for obtaining regeneration in tissue culture, and one way to identify response mutants for these hormones is to select for mutants that are impaired in regeneration in the presence of these hormones. A screen for temperature sensitive arabidopsis EMS mutants that are defective in shoot regeneration resulted in the isolation of three recessive srd mutants from a total of 2700 M3 lines [43]. Unfortunately, molecular analysis of the mutants has not been performed and thus it is not yet clear whether the mutants are impaired in hormone perception or in cell cycle initiation or progression [44]. 

The cell and tissue culture of the major tropane alkaloid-producing species does not apparently offer any special problems. The regeneration of plantlets from callus and tissue cultures seems to be routine (286,307,309,323,325,332,350-352). Plants have also been regenerated from protoplasts of Atropa belladonna (353), Duboisia myoporoides (354), and Hyoscyamus muticus (355,356). Cryopreservation has been reported for Anisodus and Datura species (349,357). 

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