Germination of Phaseolus vulgaris

Abstract

Soluble proteins from excised Phaseolus vulgaris axes incubated for 1 hour in 3H or 14C-amino acid mixtures at different times during the period leading up to initiation of cell elongation were compared by acrylamide gel electrophoresis. Differences in electrophoretic patterns were found when proteins from axes incubated during the 1st hour of imbibition were compared with proteins from axes incubated during the hour when cell elongation was initiated. These differences greatly diminished by the 2nd hour of imbibition which suggests that they were due primarily to incomplete axis imbibition. A 5-hour actinomycin D treatment which reduced amino acid incorporation by 40% in the 5th hour had no apparent effect on the electrophoretic pattern during that hour.An apparent requirement for protein synthesis prior to initiation of cell elongation has been demonstrated for several embryonic axes (2,3,9,11). Amino acid incorporation studies suggest that protein synthesis is initiated upon embryo hydration and increases in rate during the period leading to cell elongation (3, 10). Studies with protein synthesis inhibitors give some evidence for qualitative changes in the proteins synthesized prior to cell elongation (2, 10). The dependence of early protein synthesis on de novo nucleic acid synthesis appears to vary with seed type (2, 3, 7, 9, 1 1).The purpose of the present investigation was to determine if qualitative changes occur in protein synthesis prior to cell elongation in excised Phaseolus vulgaris axes. Soluble proteins labeled by in vivo incorporation of a "4C-L-amino acid mixture during the hour in which cell elongation was initiated were compared by acrylamide gel electrophoresis to soluble proteins labeled at earlier times by the in vivo incorporation of a 3H-Lamino acid mixture. 50 ,ug of chloramphenicol in 1 ml of sterile water. The flasks were shaken in a Dubnoff metabolic incubator at 26 C. After various incubation periods, the axes were transferred to flasks containing the above solution plus either a 50 tuc 'H-or a 10 ,.tc "4C-amino acid mixture of the same composition (New England Nuclear 'H amino acid mixture NET-250 or 14C amino acid mixture NEC 445). After a 1-hr incubation with the radioactive amino acid mixture, the axes were rinsed in 250-mg portions and ground with a mortar and pestle in 2 ml containing 0.01 M NaPO, buffer, pH 7, 0.4 M sucrose, 1 mM MgCl2, and 10 mm KCl. The homogenates were filtered through miracloth and centrifuged at 20,000g for 10 min. The supernatants were then centrifuged for 60 min at 104,000g, and the resulting supernatants, minus the lipid layer, were used for electrophoresis.The soluble protein from the two treatments were mixed so that 'H and 14C cpm were approximately equal. The mixtures were reduced for 1 hr at 60 C with dithiothreitol at a concentration of 700 jg/mg soluble protein. After reduction, the mixtures were dialyzed for 12 hr at room temperature against 0.1 M NaPO4, pH 7, containing 0.1% sodium dodecyl sulfate.The dialyzed mixtures were brought to ...

Effect of pre-germination treatments on germination of Aonla (Emblica officinalis Gaertn.) seeds

“…The possible reason might be due to GA 3 acts directly on embryo relieving them from dormancy through promoting protein synthesis, elongation of coleoptiles and also helps in the production of ethylene (Stewart and Freebairn, 1969). This ethylene invokes the synthesis of hydrolases especially amylase which favours the hydrolysis of starch into soluble sugars and their translocation facilitates the early initiation of radical growth by removing some metabolic blocks as suggested by Gillard and Walton (1973). Therefore, the seeds treated with GA 3 @ 500…”