In vitro organogenesis and somatic embryogenesis from punctured leaf of Populus nigra � P. maximowiczii

Explants from leaves of in vitro-grown chrysanthemum (Dendranthema grandiflora Tzvel.) cultivars regenerated adventitious shoots without an intermediate callus phase. Puncturing explants with a brush increased regenerations, but in combination with cocultivation with Agrobacterium tumefaciens it had an adverse effect on shoot formation. The negative effect of brushing and cocultivation could be overcome by preculturing explants for 8 days. Preculture altered the location of transformed sites but did not inhibit transformation. Regeneration following cocultivation with Agrobacterium is also encouraged if alternative regeneration protocols are used that do not require brushing.

Section: Discussionmentioning

confidence: 88%

Restoring adventitious shoot formation on chrysanthemum leaf explants following cocultivation with Agrobacterium tumefaciens

Jong

Rademaker

Wordragen³

1993

“…BA also showed toxic effects when it was used to induce shoot formation from callus. Although BA is widely used in tissue culture of Populus (Park & Son 1988;Russell & McCown 1988;Sellmer & McCown 1989;De Block 1990), toxicity has been reported (Coleman & Ernst 1989).…”

Section: Discussionmentioning

confidence: 99%

Agrobacterium-mediated transformation of hybrid poplar suspension cultures and regeneration of transformed plants

Howe

Goldfarb

Strauss

1994

A method for Agrobacterium-mediated transformation of hybrid poplar (Populus alba × P. grandidentata cv. 'Crandon') suspension cultures and regeneration of transformed plants is described. Transformants were recovered when suspension cultures were inoculated with Agrobacterium tumefaciens at a density of 107 colony-forming units ml -~, cocultivated for 48 h, and plated to cellulose acetate filters on Woody Plant Medium containing 4.5 IxM 2,4-dichlorophenoxyacetic acid and 250 mg 1-1 cefotaxime. Levels of cefotaxime greater than 250 mg 1-1 were unnecessary for control of residual bacteria and inhibited callus growth. Transgenic plants were regenerated by culturing the transformed callus on media containing 0.11 to 27 IxM thidiazuron. In contrast to thidiazuron, N6-benzyladenine had a negative effect on shoot regeneration; the callus became necrotic when we attempted to induce shoots with concentrations of 1.1 to 8.9 IxM, and growth was inhibited when concentrations of 0.11 or 0.22 p,M were used to regenerate callus from suspension cultures. Following cocultivation of poplar suspension cultures, we recovered transgenic plants containing the maize transposon Ac, and callus containing an insect toxin gene from Bacillus thuringiensis.

“…cell group, leading to further proliferation of single cells or smaller groups. A related study was reported on the promotion of organogenesis and somatic embryogenesis in punctu/ed leaf of Populus nigra x P. maxiraowiczii, a woody species (Park & Son 1988). It can be inferred that the induction of direct somatic embryogenesis observed from hyperhydrated plantlets is an alternative pathway for the expression of stress response of the hyperhydrated tissue.…”

Section: Discussionmentioning

confidence: 99%

Picolinic acid-induced direct somatic embryogenesis in sweet potato

Desamero

Rhodes

Decoteau

et al. 1994

Somatic embryos are being considered as an alternative material for in vitro germplasm conservation of sweet potato [(Ipomoea batatas (L.) Lam.)]. Picolinic acid was tested for somatic embryo production in sweet potato apical meristem tip cultures. Low level (0.2 mg1-1) of picolinic acid combined with kinetin or 6-benzylamino purine (6-BAP) (1.0 and 2.0 mg1-1) suppressed shoot growth and induced callus proliferation. Increased amount of picolinic acid (2 and 3 mg1-1) in combination with kinetin (0.25 and 1.0 mg1-1) induced direct somatic embryogenesis from apical meristem tips of variety Regal but not in Jewel. The primary embryos matured and germinated bipolarly yielding whole plantlets and unipolarly producing embryogenic hyperhydrated-fasciated shoots. The hyperhydrated-fasciated shoots, when cultured in picolinic and kinetin-enriched medium, produced secondary embryos. The secondary embryos also germinated bipolarly and unipolarly, resulting in subsequent cycles of embryogenesis. This recurrent embryogenesis ensures maintenance and proliferation of embryogenic tissues. Somatic embryos were also formed in mannitol-induced hyperhydrated shoots in response to picolinic acid and kinetin or 6-BAP treatment. Embryogenesis did not occur in non-hyperhydrated leaf, petiole, and internode sections.