Ethylene Production by Sunflower Cell Suspensions

Abstract

From a variety of undifferentiated plant cell suspensions, 2,4-dichlorophenoxyacetic acid-dependent cells of sunflower (Helianthus annuus L. Spanners Allzweck) produced large quantities of ethylene. The maximum rate was about 1 nanomole x gram fresh weight-' x hour-' during the exponential growth phase. The action of various compounds known to interfere with ethylene formation in plant tissue was studied in sunflower cell suspensions. The influence on ethylene, 1-aminocyclopropanecarboxylic acid (ACC), and N-malonyl-ACC (MACC) Undifferentiated plant cell suspensions are able to produce ethylene depending on the kind of plant from which the cell originated but also on their physiological state (2-4, 15, 17, 21, 24). With respect to its physiological significance, data suggested no functional relationship between growth and ethylene synthesis (10,15,24). Ethylene was assumed to be a by-product of actively dividing cells. Nevertheless, undifferentiated cell suspensions should be an appropriate tool for analyzing in detail the effects of biologically active compounds on cellular ethylene biosynthesis.In particular, plant growth retardants of the norbornenodiazetine (e.g. tetcyclacis) and triazole (e.g. LAB 150 978) type inhibited both the formation of ethylene and shoot growth of sunflower seedlings (25). Likewise, preliminary results indicated that both compounds decreased the ethylene production and cell division rate in cell suspensions of sunflower (24). Although their mode of action in regulating growth processes is seen in an interaction with gibberellin and to some extent sterol biosynthesis (5,7,12,22), the question arises as to whether there is a direct effect on ethylene biosynthesis, too.In the work reported we have analyzed the levels of ethylene and ACC2 produced in undifferentiated sunflower suspension cells under the influence of the growth retardants tetcyclacis and LAB 150 978. In addition to ACC, the direct precursor of eth-' Dedicated to Professor Dr. Helmut Doerfel on the occasion of his 60th birthday. The cells, grown in culture for several years, were subcultured at intervals of 7 d in the exponential growth phase under the following conditions: 250 ml Erlenmeyer flasks containing 80 ml of cell suspension were shaken on a rotary shaker at 110 rpm in the dark at 25°C. Solutions of chemical compounds used were prepared in acetone or in water (sterile-filtered) and were added to the medium shortly before inoculation. The final acetone concentration in the medium (1%) had no adverse effects on the growth of the culture.

Are ethylene and 1-aminocyclopropane-1-carboxylic acid involved in the induction of chitinase and ?-1,3-glucanase activity in sunflower cell-suspension cultures?

“…As previously shown, the growth-regulating potency of BAS l ll..W and other N-heterocyclic retardants is caused by an inhibition of cytochrome P-450-dependent monooxygenases particularly involved in gibberellin biosynthesis (Grossmann 1992;Rademacher 1992). In contrast, the interference of the compounds in ethylene biosynthesis was suggested to be caused either by a direct blockage of the ethylene-forming enzyme or by an indirect effect on cellular membrane properties (Sauerbrey et al 1988). …”

“…Data indicated that peak levels of ethylene during the exponential growth phase were synthesized by the cells via the ACC pathway (Sauerbrey et al 1988). No functional relation has been observed between growth of the culture and ethylene formation (Sauerbrey et al 1988).…”

“…Undifferentiated, auxin-dependent sunflower cell suspensions have been shown to provide an appropriate system for characterizing cellular ethylene biosynthesis (Sauerbrey et al 1988) and possible interrelations with other endogenous bioregulators (Grossmann et al 1993). Data indicated that peak levels of ethylene during the exponential growth phase were synthesized by the cells via the ACC pathway (Sauerbrey et al 1988).…”

Efeito do Paclobutrazol no controle da diferenciação floral natural do abacaxizeiro cv. Smooth Cayenne

“…Sauerbrey et al (1988) afirmaram que os inibidores vegetais podem provocar a inibição da síntese do etileno, pois, em plântulas de girassol, a formação de etileno foi reduzida significativamente por triazóis. A inibição foi acompanhada pela elevação no nível de ACC (1-aminociclopropano-1-carboxílico), enquanto os níveis de N-malonil-ACC permaneceram inalterados, sugerindo que a conversão de ACC a etileno, catalisada pela enzima ACC oxidase, foi influenciada pelos inibidores vegetais.…”

Inhibition of ethylene production in sunflower cell suspensions by a novel oxime ether derivative

“…Data suggested that at least the final steps in the ethylene synthesis of the cells are identical to those of intact plants (Sauerbrey et al 1988).…”