Carbohydrate-limited Growth Kinetics of Tobacco (Nicotiana rustica L.) Callus

Abstract

Logistic curves were fitted to sigmoidal growth data obtained from tobacco (Nicotiana rustica L.) callus grown on media prepared with 0.1, 0.03, 0.01, and 0.003 M sucrose. Analysis of the growth curves indicated that final yields and specific growth rates were influenced by the initial sucrose concentration. Growth yields from the four treatments were similar (0. MATERIALS AND METHODSTobacco callus cultures grown on Linsmaier and Skoog's medium (10) were used following preliminary tests with a large number of cultivars of four species on four basic media with a range of hormonal concentrations. The Linsmaier and Skoog medium was developed with a view towards optimizing medium requirements for growth (10, 11) and, with tobacco, gave us the highest growth rates of relatively undifferentiated callus.The callus was generated from the culture of internodal pith explants from greenhouse-grown tobacco plants (Nicotiana rustica L.). After several subcultures on Linsmaier and Skoog's medium (10) in darkness at 27 C, three vigorously growing pieces were dissected for inoculum.Ninety-six, 125-ml Erlenmeyer flasks containing 40 ml of Linsmaier and Skoog's medium were prepared for inoculation with four treatment sucrose concentrations (0.1, 0.03, 0.01, and 0.003 M). Cytokinin was added at a nonlimiting concentration (0.93 uM kinetin). All flasks were inoculated with four evenly spaced pieces of tobacco callus (3 mm3 per piece). The callus was firm to cut but disintegrated easily. Loose tissue was not used as inoculum as the size could not be estimated. The flasks were incubated in darkness at 27 C.Fresh and dry weight measurements were made of 20 pieces of inoculum (collectively) and of the callus from six randomly selected flasks for each treatment on four sampling dates: 7, 28, 43, and 55 days after inoculation. Dry weights were determined after drying for 24 hr in a Thermo-Vac RD-6 freeze-dryer. RESULTSThe growth of tobacco callus for the four sucrose supply treatments is illustrated in Figure 1. Yields followed a sigmoidal pattern with time and weighted logistic growth curves were fitted to the data by an iterative program that minimized the residual variance of the data points from the curve.

A biophysical model of fruit growth: simulation of seasonal and diurnal dynamics of mass

“…Uptake of solutes includes passive permeation of solute through the membrane, ‘solvent drag’ by the mass flow of the water, and active transport. The active and/or facilitated transport makes an important contribution to the uptake of dry materials by fruits, as studied in tomato (Milner, Ho & Hall 1995), in peach (Vizzotto et al 1996) and in tobacco callus (Hunt & Loomis 1976). Influx of water and solutes into the cells leads to irreversible changes in the volume if it is accompanied by cell wall extension.…”

Characteristics of Sugar Uptake in Hypocotyls of Cotton

“…Growth, as measured by dry weight accumulation, can be strongly determined by the kinetics of synthetic reactions. Hunt and Loomis (13) demonstrated the relationship of tobacco callus growth to external sucrose concentration. Their results described a rectangular hyperbola with a Km of 3.7 mm.…”

“…For the whole plant, there is considerable evidence that the most limiting factor to assimilate availability is assimilate production rather than vascular transport capacity. Investigation of the substrate dependence of growth rate in callus by Hunt and Loomis (13) suggested that the movement of assimilates within the sink tissue is also important.…”

Dynamical Transitions in a Pollination–Herbivory Interaction: A Conflict between Mutualism and Antagonism

“…root, stem and leaf biomass are being constantly renewed). For the sake of simplicity and because we want to focus on the plant–insect interaction, we describe vegetative growth using a logistic growth rate, a choice that is empirically justified for tobacco plants [ 18 ]. In the absence of the plant, however, the insect always goes extinct because larval development relies exclusively on herbivory, even if adults pollinate other plant species.…”