Polyamine Anabolism in Germinating Glycine max (L.) Seeds

Abstract

ABSTRACIActive polyamine biosynthesis occurs in the embryonic axis, but not in the cotyledons, during germination of Glyciac max (L.) further elucidated. To understand the potential roles of polyamines in cellular metabolism, it is necesary to clarify whether changes in the content of polyamines in general or a specific polyamine is causally linked to, or merely a consequence of, plant growth and development. In this study, polyamine levels and complexities were determined in the cotyledon, hypocotyl hook, hypocotyl, and radicle of soybean (Glycine mnax L. Merr.) cv Williams during and after seed germination. Experiments were also carried out to characterize Cad biosynthesis in the embryonic axis during seed germination and growth ofthe young seedling. MATERIAIS AND METHODS Plant Material. Seeds of the soybean (Glycine max L. Menf.) cv Williams harvested in 1982 from Spindletop ExperimentalFarm of the University of Kentucky were used in this study. Unless otherwise noted, seeds were allowed to germinate at 23°C in the dark on water-moistened Anchor seed germination paper (Anchor Paper Co., St. Paul, MN). Samples were taken at intervals throughout germination and the cotyledons and germinated embryonic axes were manually separated. Unless otherwise stated, each of the embryonic axes was divided into three parts (radicle, hypocotyl, and hypocotyl hook) for determination of fresh weight, dry weight, and polyamine content. The axes could be clearly divided into the above three distinguishable parts by 2 d after the seeds were placed on the water-moistened germination paper. The axes from dry seed or seed that had been on the germination paper for up to 1.5 d were divided by length with one-quarter the length from the apex desgnated as the radicle, the following one-quarter length as the hypocotyl, and the remaining part as the hypocotyl hook. The separation of the hypocotyl hook from the hypocotyl is based on the observation that the hypocotyl hook portion turns greenish in color within hours after exposure to light ofdetached embryonic axes cultured in a nutrient agar medium (20). The hook portion in darkgerminated seedlings is yellowish in color.Analysis of Polyamine Content. Routinely, the fresh tissue derived from 30 embryonic axes (300-800 mg fresh weight) per assay was homogenized in 5 ml ofcold 5% HC104 with a Polytron tissue homogenizer. Polyamines in the acid-soluble and -insoluble fractions were qualitatively and quantitatively determined by a HPLC system as described previously (10). In some experiments, 5 to 15 seedlings (after 3 d of imbibition) were used per assay and the seedlings were homogenized as described. Authentic polyamines were used for calibration of polyamine content in the extracts.

Distribution of diamine oxidase activity and polyamine pattern in bean and soybean seedlings at different stages of germination

“…As far as cotyledons are concerned, DAO activity is detectable only at stage 1 in soybean, while in bean it is high and increases throughout germination. In the latter case this might be due to hydrolysis of storage substances and to the transport of polyamines and/or their metabolites to the embryo axis, as shown to occur in the same species (Bagni 1970), In soybean cotyledons 40^50% of the lysine resulting from the breakdown of the cotyiedonary proteins ends up in cadaverine whose synthesis has been observed in hypocotyls and radicles (Lin 1984) as well as its oxidation (Tab. 1), In conclusion, the different patterns of DAO activity observed are probably linked to the regulation of the cellular level of polyamines.…”

Purification, cDNA cloning and Northern‐blot analysis of mitochondrial chaperonin 60 from pumpkin cotyledons

“…The biological phenomena of adaptation to stress are complex and many biological macromolecules, including proteins and lipids, must be involved in the processes of such adaptation. Molecular chaperones are assumed to be involved in adaptation to stress because of their ability to refold partially denatured polypeptides, to bind to denatured polypeptides so as to prevent or slow down their aggregation and to dissolve hydrophobic aggregates of proteins formed under normal or stress conditions [7, 14-171. It has been shown that some plant seedlings can acquire induced thermotolerance to lethal high temperatures through a prior treatment at a lower, non-lethal high temperature [18]. Since treatment at non-lethal high temperatures that induces thermotolerance also induces the synthesis of heat-shock proteins, it is assumed that these proteins participate in protection of cells from the effects of extreme high temperatures [18].…”

Putative occurrence of lysine decarboxylase isoforms in soybean (Glycine max) seedlings

“…In plants the polyamine cadaverine (1,5-diaminopentane) is synthesized from lysine by lysine decarboxylase enzyme (LDC,EC 4.1.1.18). This compound is present in various bacteria and several higher plant families such as Gramineae, Poaceae, Solanaceae and in particular in Leguminosae (Bagni et al 1986;Lin 1984;Rodrı ´guez et al 2000;Smith and Wilshire 1975). In the Leguminosae family, decarboxylation is the main pathway of cadaverine synthesis, although it can also be synthesized from homoarginine via homoagmatine, metabolites that are present during seed germination (Smith 1977).…”

“…Similarly, some Leguminosae contain a large amount of cadaverine (Federico and Angelini 1988) which can be converted into aminopropylcadaverine and bis (aminopropyl)cadaverine, as also suggested in H. tuberosus explants by Bagni et al (1981). Although the plant distribution of cadaverine and the activity and localization of diamine oxidases cadaverine catabolic enzymes (Lin 1984;Smith and Barker 1988;Scoccianti et al 1990;Torrigiani and Scoccianti 1995), were extensively studied in Leguminosae during seed germination and development, little attention has been given to lysine decarboxylase activity and its regulation in vitro and in vivo. The present study examines lysine decarboxylase activity in both soluble and particulate fractions of soybean (Glycine max (L.) Meer cv.…”