Cultured leaf sections of 12 cultivars of tomato, Lycopersicon esculentum Mill., were evaluated concerning their morphogenic responses to 24 combinations of indoleacetic acid (IAA, 0–2.0 mg/liter) and 6-benzylamino purine (BA, 0–10 mg/liter). Morphogenic responses were cultivar-dependent and exhibited broad maxima over a range of growth regulator concentrations. Media containing 0.2 mg/liter IAA and 1.0 or 5.0 mg/liter BA were optimal callus induction media for most cultivars. Leaf explants of all cultivars rooted on a medium supplemented only with 0.2–2.0 mg/liter IAA. Genotypic differences were observed in ability to regenerate shoots and average number of shoots regenerated. Optimal shoot regeneration medium varied with cultivar, but most often contained 0.2 or 1.0 mg/liter IAA + 2.5 or 5.0 mg/liter BA. ‘Better Boy’, ‘Starfire’, and ‘UC 134-1-2’ regenerated shoots most readily, averaging more than 10 shoots per culture. ‘Starfire’ was most amenable to in vitro shoot regeneration with as many as 19 shoots per culture.
The effects of woody plant medium (WPM) with various formulations and concentrations of Cu+2 on in vitro rooting and subsequent shoot growth of microcuttings of a Betu pubescens × papyrzfera (birch) clone were monitored for 28 days. Adventitious root initiation and elongation were reduced in magnitude and slowed in development by moderate to high Cu (as CuSO4·5H2O) concentrations, with near zero root regeneration occurring at 157 μm Cu. Shoot growth was also inhibited by 157 μM Cu as cupric sulfate. Copper-toxicity symptoms (senescent leaves, necrotic stems, and bulbous and stunted roots) were significantly increased by moderate to high levels (≥ 79 μm) of Cu as cupric sulfate. Microcuttings responded differently to Cu+2 applied as cupric chloride (CuCl2·2H2O). Root initiation, root elongation, and root branching were increased by moderate concentrations of Cu as cupric chloride. Shoot growth was slightly stimulated by cupric chloride at moderate levels. No significant increase in Cu-toxicity symptoms was observed at concentrations up to 157 μm Cu as cupric chloride. Cupric acetate [Cu(CH3 COO);H2O] and cupric carbonate [CuCO3·Cu(OH)2] produced more severe Cu-toxicity symptoms than cupric sulfate. Root regeneration and shoot growth were inhibited and increased Cu-toxicity symptoms were apparent even with low concentrations (39 μm) of Cu as cupric acetate or cupric carbonate. There was little or no effect on root regeneration when the Cu+2 in cupric sulfate was replaced by different cations, i.e., magnesium sulfate (MgSO4·7H2O), calcium sulfate (CaSO4·2H2O), and sulfuric acid (H2SO4), a result suggesting that the observed responses could be attributed to the Cu+2 concentration. Changes in media pH did not correspond to Cu-toxicity symptoms or alterations in root or shoot growth by the Cu compounds.
Microscopic examination of longitudinal tangential sections of stems of rose (Rosa hybrida L. cv. Red American Beauty) revealed vascular occlusions due to microbial growth and gum deposition. Microbial occlusions reacted positively with the protein stain mercuric bromphenol blue and were restricted to the basal 2.5 cm of the stem. Gum deposition was identified by a positive reaction with periodic acid-Schiff's reagent and gas liquid chromatographic analysis of monomer content of acid-hydrolyzed occluding material. Location of gum deposition was dependent on the depth of the holding solution on the stem, always occurring above the solution level. Quantitative and qualitative comparison of sugar and uronide monomer content between areas of no gum deposition and areas of high gum deposition showed no differences, suggesting that gum formation was due to redeposition rather than net synthesis of gum constituents.