Polyamines and cytokinins in celery embryogenic cell cultures

Abstract

The effect of inhibitors of polyamine biosynthesis on the development of embryogenic cell cultures of celery (Apium graveolus L.) was studied. Several developmental stages of somatic embryos were compared for differences in the content and biosynthesis of free polyamines and for cytokinin content. Cyclohexylamine and particularly methylglyoxal bis(guanylhydrazone), inhibited both cell division and the organization of polar embryos from globular embryos. Difluoromethylornithine slightly promoted embryo development, especially cell division.The free putrescine content of globular embryos was 6-fold that of fully differentiated plantlets, and that of spermidine 2-fold. Only a slight increase in the spermine content was found with embryo development. These differences were confirmed by data from polyamine biosynthesis. Incorporation of 14C-arginine into polyamines was slightly higher than that of 14C-ornithine. Over 96% of this incorporation was detected in the putrescine fraction. Incorporation of 14C into putrescine in globular embryos was 3 to 4-fold that in fully-differentiated plantlets. Incorporation into spermidine and spermine was, however, higher in plantlets than in globular embryos.Cytokinin analysis revealed considerable differences in the biological activity between the developmental stages of embryogenesis. This could be due to endogenous cytokinins and/or BA taken up from the maintenance medium. Cytokinin levels decreased with increased embryo development. Most of the detected cytokinin-like activity co-chromatographed with BA and its metabolites. Some as yet unidentified peaks of activity were recorded in the globular embryos.The results are considered with respect to the possible participation of polyamines and cytokinins in the development of embryogenic cell cultures of celery. It is suggested that the onset of embryogenesis is characterized by a high content of putrescine and cytokinins, while a decrease in putrescine synthesis and cytokinin content, and an increase in spermidine and spermine content, accompany further embryo development and plantlet formation.Abbreviations: ADC = arginine decarboxylase; ODC = ornithine decarboxylase; 2,4-D = dichlorophenoxyacetic acid; DFMA = difluoromethylarginine; DFMO = difluoromethylornithine; MGBG = methylglyoxal bis(guanylhydrazone); CHA = cyclohexylamine; BA = benzyladenine; BAR = benzyladenine riboside 246

IAA, ABA, polyamines and free amino acids associated with zygotic embryo development of Ocotea catharinensis

“…Elevated concentration of Spm are Table 1 Free amino acids contents (lg g -1 MF) in O. catharinensis developing embryos at stages early-heart with endosperm (1), pre-cotyledonary with endosperm (2), cotyledonary with endosperm (3), cotyledonary (4) and mature (5) Amino essential from the middle to the end of embryo development, when growth is mainly due to cell elongation. Similar results were obtained in zygotic embryogenesis of Apium graveolens (Danin et al 1993), P. radiata. (Minocha et al 1999) and…”

Inhibition of direct somatic embryogenesis by ?-difluoromethylarginine in a Cichorium hybrid: effects on polyamine content and protein patterns

“…In addition, the low amounts of putrescine and sperm• in the presence of DFMA indicated that putrescine was synthesised from arginine through the arginine decarboxylase (ADC) pathway, confirming previously published data on Cichorium root tissues (Saudemont et al 1992). The ADC pathway has been confirmed by most studies on indirect somatic embryo differentiation using biosynthetic inhibitors [Apium graveolens (Danin et al 1993 (Hilbert et al 1992 ;Boyer et al 1993) and somatic embryogenesis, the polypeptide patterns obtained during embryogenesis in the presence or absence of D F M A were compared in 1-to 5-d-old induced leaves and in induced leaves collected after transfer for 3 and 7 d to expression medium. We focused on the 15 SER polypeptides described by Boyer et al (1993).…”

“…Polyamines have been studied in relation to indirect somatic embryogenesis in species such as Apium graveolens (Danin et al 1993), Daucus carota (Feirer et al 1985), Hevea brasiliensis (El Hadrami et al 1989; E1 Hadrami and d'Auzac 1992), Medicago sativa (Meijer and Simmonds 1988), Solanum melongena (Fobert and Webb 1988) and Vitis vinifera (Faure et al 1991). In Cichorium we have reported an increase in free polyamines, and particularly in putrescine, during somatic embryo differentiation in root fragments in which no synchronisation of the first division of the embryogenic cells was obtained (Couillerot et al 1993).…”

Morphogenic Aspects of Somatic Embryogenesis

“…Endogenous cytokinin levels have been observed to decrease as development occurs in both zygotic embryos of soybean [183] and somatic embryos of celery [184]. Furthermore, exogenous cytokinins can lead to abnormal development or suppression of the main embryo axis [43].…”