Medium and Tissue Sugar Concentrations during Cytokinin-Controlled Growth of Tobacco Callus Tissues

Helgeson, John P.; Upper, Christen D.; Haberlach, Geraldine T.

doi:10.1007/978-3-642-65406-0_65

Cited by 3 publications

(3 citation statements)

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“…Vol. 52, 1973 DISCUSSION Logarithmic growth rates of tobacco callus tissues are, within certain limits, controlled by exogenous cytokinin rather than by inorganic minerals or sugars (5)(6)(7)11). These logarithmic growth rates, programmed by the cytokinin concentration, appear to be decreased reproducibly, quickly and reversibly by low concentrations of T-2 toxin.…”

Section: Resultsmentioning

confidence: 98%

“…This toxin is one of more than twenty 12, 13-epoxytrichothecene toxins that affect both plants and animals (1,3,9). For example, Marasas et al (9) reported that growth (fresh weight and length) of pea seedlings was depressed (5,6) and sugar in callus medium (7,11) were measured as previously reported. Growth substances and T-2 toxin were autoclaved in the medium; their concentrations are reported for each experiment.…”

mentioning

confidence: 93%

“…Maximal yields of callus, on the other hand, are dependent on the sugar concentration (7,11). A reversible inhibitor that decreases growth rates in log phase, without decreasing maximal yields, could be valuable in determining the mechanism by which cytokinins control growth rates.…”

Section: Introductionmentioning

confidence: 99%

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T-2 Toxin Decreases Logarithmic Growth Rates of Tobacco Callus Tissues

1973

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T-2 toxin, a mycotoxin produced by Fusarium tricinctum, decreases logarithmic growth rates of tobacco (Nicotiana tabacum L.) pith callus tissues. Toxin concentrations as low as 0.003 ,uM will decrease growth rates; a concentration of 0.081 aM will halt growth completely. Additional exogenous cytokinin will reduce the inhibition by toxin only when the initial cytokinin and toxin concentrations are quite low (about 0.01 jaM). When inhibited tissues are transferred to media lacking toxin, they assume the faster, control rates ahnost immediately. Maximal yields of tissue (yields at the point at which no sugar was detected in the medium) are not affected by toxin concentrations of 0.01 to 0.036 ,uM.Logarithmic growth rates of tobacco pith callus tissues can be controlled by the concentration of exogenous cytokinin supplied in the growth medium (5, 6). Maximal yields of callus, on the other hand, are dependent on the sugar concentration (7,11). A reversible inhibitor that decreases growth rates in log phase, without decreasing maximal yields, could be valuable in determining the mechanism by which cytokinins control growth rates. Such an inhibitor would make it possible to vary growth rates without changing cytokinin concentration. We now report that T-2 toxin, a naturally occurring mycotoxin, is such an inhibitor.T-2 toxin, 4,15-diacetoxy-8-(3-methylbutyrloxy)-12,13 expoxy-A'-trichothecene-3-ol, is produced by Fusarium tricinctum (cda.) Snyd. & Hans. This toxin is one of more than twenty 12, 13-epoxytrichothecene toxins that affect both plants and animals (1, 3, 9). For example, Marasas et al. (9) reported that growth (fresh weight and length) of pea seedlings was depressed RESULTSInitial experiments indicated that T-2 toxin decreased callus yields when supplied at concentrations ranging from 0.003 to 0.081 ,uM (Fig. 1). At low 2iP' and T-2 concentrations, 2iP can decrease toxin inhibition to a limited degree.When the growth of the tissues was followed with standard kinetic measurements, tissues supplied with 11.5 Mm IAA, 0.1 Mm 2iP, and 0, 0.018, or 0.036 Mm T-2 toxin grew logarithmically with doubling times of 3.3, 5.5, and 7.55 days, respectively (Fig. 2).The reversibility of T-2 toxin inhibition is illustrated in Figure 3. Tissues were planted initially on medium containing 11.5 ,uM IAA and 0.1 puM 2iP, with or without 0.018 ,uM T-2 toxin. After 14 days, some tissues treated with toxin were transferred to fresh medium containing 11.5 uM and 0.1 uM 2iP, but without toxin. Almost immediately after transfer from toxin medium, tissues assumed the same growth rate as the tissues that had never been treated with toxin.Measurements of medium sugar for the experiment shown in Figure 2 indicated that 0.68, 0.74, and 0.65 g dry weight of tissue was produced/g sucrose during log phase from tissues treated with 0, 0.018, or 0.036 uM toxin, respectively. In a subsequent experiment, toxin-treated and control tissues were allowed to go to maximal yield (the point at which no sugar was detected in the medium). Dry we...

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Section: Resultsmentioning

confidence: 98%