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An assessment was made of various parameters to measure growth of soybean [Glycine max (L.) Merr. ‘Wilkin’] and einkorn (Triticum monococcum L.) cell suspension cultures to establish convenient methods of screening the effects of chemicals. Methods assessed were settled cell volumes, packed cell volumes, absorbance at 525 nm of sonicated aliquots, dry weights (of aliquots or entire flask contents), and electrical conductivity and pH of the culture medium. Settled cell volumes, conductivity, and dry-weight changes were the most useful of the methods tested for determining the phytotoxicity of a nonionic linear alcohol ethylene oxide detergent (an adduct of 1-dodecanol containing eight ethylene oxide units) and the methyl ester of diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid}. Because 3 to 4 weeks were required to assess whether the cultures could grow out of the initial inhibition by the detergent or herbicide, none of the methods was rapid. Advantages and disadvantages of the various methods and their relative values for screening compounds are described.

Abstract:Plants were regenerated from leafy spurge (Euphorbia esula L.) cell suspensions obtained from stem callus. A North Dakota accession was highly regenerable, but two accessions from Oregon and Austria formed only a few plantlets. Organogenesis occurred in media without growth regulators, under fluorescent lights (30 to 90 µE m -2 s -1 , 14-hour photoperiod). Organogenesis was greatest in larger size clumps subcultured during maximum cell growth into media containing a reduced:oxidized nitrogen ratio of 33:67. Roots formed first and some clumps produced shoots. Organogenic suspension cultures also were initiated from hypocotyl and root segments of germinated seedlings, directly in liquid medium. Plantlets of the North Dakota accession formed in vitro adapted to greenhouse conditions. They were phenotypically similar to the parent plants.

Ultrastructural alterations of soybean cell suspension cultures treated with a homogeneous linear alcohol ethylene oxide nonionic surfactant, the octa(oxyethylene) adduct of 1-dodecanol (at concentrations below the critical micelle concentration), were determined at 0.5, 3, and 10 days. Treatments were 4 μM (2 ppm; nonphytotoxic), 11 to 17 μM (6 to 9 ppm; inhibitory), and 28 μM (15 ppm; phytotoxic). Plastids and mitochondria appeared to have reduced amounts of internal membranes at 0.5 days, even at sublethal concentrations. At 3 days after treatment, cells treated with up to 17 μM detergent looked similar to control cells, except for void regions in some organelles. Cells treated 0.5 days with 28 μM had plastids with few membranes and much reduced starch compared with controls; by 3 days, these cells were badly damaged, although numerous organelles still could be recognized and lipid bodies were spherical. Distinctive myelin-like membrane whorls were present in some 3-day 28 μM treated cells. Even at 10 days recognizable organelles in cells included nuclei, plastids, some endoplasmic reticulum and some flattened nuclei with irregularly shaped nucleoli. Starch granules were conspicuously free of the plastids in which they were formed. Lipid bodies were often angular in shape rather than spherical. Outer envelopes of organelles often remained, even though their internal structures were destroyed or altered greatly.

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