Somatic embryogenesis was achieved from leaves of Agave tequilana Weber cultivar azul utilizing MS medium supplemented with L2 vitamins and the addition of cytokinins: 6-benzylaminopurine (BA), 1-phenyl-3(1,2,3-thiadiazol-5-yl)urea (TDZ), 6-(γ-γ-dimethylamino)purine (2ip) and 6-furfurylaminopurine (KIN), combined with the auxin 2,4-dichlorophenoxyacetic acid (2,4-D). Differences among the six genotypes studied with regard to their embryogenic response in culture were found. Embryos produced by genotype S3 under a hormone regime of high cytokinin (44.4 to 66.6 μM BA) compared to auxin (4.5 μM 2,4-D) contained chlorophyll, whereas those produced when auxin was high compared to cytokinin (9.0 and 13.6 μM 2,4-D and 1.3 and 4.0 μM BA, respectively) were whitish and morphologically similar to their zygotic counterparts. Somatic embryos matured and germinated after transferring the embryogenic calli to maturation and germination medium without growth regulators and enriched with organic nitrogen. Microscopic observations demonstrated a unicellular origin for production of indirect somatic embryos.

Diamines and polyamines are ubiquitous components of living cells, and apparently are involved in numerous cellular and physiological processes. Certain "uncommon" polyamines have limited distribution in nature and have been associated primarily with organisms adapted to extreme environments, although the precise function of these polyamines in such organisms is unknown. This article summarizes current knowledge regarding the occurrence in higher plants of the uncommon polyamines related to and including norspermidine and norspermine. A putative biosynthetic pathway to account for the occurrences of these uncommon polyamines in higher plants is presented, with a summary of the supporting evidence indicating the existence of the requisite enzymatic activities in alfalfa, Medicago sativa L.The term "polyamines" is used here as a collective term for the naturally occurring diamines

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Plant regeneration through direct somatic embryogenesis of leaf blade explants from in vitro propagated plants of Agave victoria-reginae Moore, is described. Somatic embryogenesis was evident in a 6-week period on agarsolidified MS medium supplemented with L2 vitamins and 2,4-dichlorophenoxyacetic acid (1,4 #M), and germination of somatic embryos was achieved after 8 weeks on half-strength MS medium and 4 weeks on half-strength SH medium, both lacking growth regulators. Hyperhydricity of somatic embryos and plantlets was reduced by the use of vented culture vessel lids during the last 4 weeks on SH medium. Shoot proliferation was obtained, and hyperhydricity was eliminated on a modified MS medium (with NH4NO3 reduced to 5 mM) supplemented with kinetin (4.6 #M) and 1-naphthaleneacetic acid (1.6 #M) and the use of vented culture vessel lids.

Shoot meristem tissues of alfalfa, Medicago sativa L., were found by high performance liquid chromatography analyses to contain the uncommon polyamines, norspermidine and norspermine. The chemical structures of norspermidine and norspermine, purified from alfalfa, were confirmed by comparison of mass spectra with those from authentic standards. The discovery of norspermidine and norspermine in alfalfa implicates the presence of at least two biosynthetic enzymes, a polyamine oxidase and a previously uncharacterized aminopropyltransferase.Much research has implicated the naturally occurring diamine, putrescine,2 and the polyamines, spermidine and spermine, in processes controlling cellular growth in prokaryotes, higher animals, and plants. They are involved in numerous aspects of plant growth, developmental processes, and in the response of plants to specific abiotic stress stimuli especially at the level of the membrane (1,(20)(21)(22). In microbial systems, polyamines have been shown to modulate membrane fusion, exhibit differential preferences for alignment of membrane phospholipids, and mediate preferential attachment or expulsion of membrane surface proteins (15). These and other observations have important implications for protection by polyamines of the structural integrity and function of both prokaryotic and eukaryotic organisms susceptible to osmotic shock (14).Relatively little is known about the occurrence of other structurally related and uncommon polyamines such as norspermidine, norspermine, or the higher mol wt pentamines and hexamine. These uncommon polyamines were initially discovered in some thermophilic (6,16) lichens, certain fungi (10), and eukaryotic algae (9), but not in Pteridophyta or in higher plants (10).The investigation of the distribution of the uncommon polyamines in biological systems is far from complete. Thus, during a study in our laboratory of the changing patterns of polyamine titers among related populations of drought tolerant and drought susceptible alfalfa in response to imposed stress conditions (17, 18), attention was given to the identification of new polyamines apart from the more common putrescine, spermidine and spermine. In this communication, we report analytical and structural evidence for the occurrence of norspermidine and norspermine in alfalfa.