An unusual minor protein appearing in embryonic axis cells of haricot bean seeds following germination process stimulated by 6-methylthiouracil

Using the two-dimensional poly aery lamide gel electrophoresis approach, an unusual » 30 kDa protein was found in embryonic axis cells of haricot bean seeds following seed germination process stimulated by 6-methylthiouracil. No similar protein was found both in control and lutidine N-oxide stimulated seeds. The synthesis of an additional low molecular weight protein was also detected in a cell-free system prepared from rabbit reticulocytes in the presence of poly(A)RNA isolated from 6-methylthiouracil stimulated embryonic axes of haricot been seeds. At the same time the lutidine N-oxide was found to stimulate drastically the total polypeptide synthesis in an in vitro system prepared from wheal embryo in the presence of a «standard» poly(A)RNA preparation, no similar effect of the 6-methylthiouracil having been seen. The mtio of informosomes, free and incorporated into polyribosomes, was investigated following RNP-particles fractionation in a preformed CsCl gradient; the 6-methylthiouracil seed stimulation was shown to induce the development of an additional peak of synthetically active informosomes, their buoyant density being J.46 glcm . The 6-methylthiouracil stimulated seed germination causes a significant shortening of haricot plant ontogenesis period without any harmful changes of plant phenotype, the lutidine N-oxide stimulation leads, however, to deformed accelerated vegetative organ appearance accompanied byno reproductive organ development. Nature of 30 kDa protein as well as some problems concerning the correlation between different stimulator-induced cellular gene expression changes taking place during early postetnbryogenesis and further processes of haricot bean plant growth and development are discussed; some possible practical consequences of our experiments arc also mentioned.


Using the two-dimensional poly aery lamide gel electrophoresis approach, an unusual » 30 kDa protein was found in embryonic axis cells of haricot bean seeds following seed germination process stimulated by 6-methylthiouracil. No similar protein was found both in control and lutidine N-oxide stimulated seeds. The synthesis of an additional low molecular weight protein was also detected in a cell-free system prepared from rabbit reticulocytes in the presence of poly(A) + RNA isolated from 6-methylthiouracil stimulated embryonic axes of haricot been seeds. At the same time the lutidine N-oxide was found to stimulate drastically the total polypeptide synthesis in an in vitro system prepared from wheal embryo in the presence of a «standard» poly(A) + RNA preparation, no similar effect of the 6-methylthiouracil having been seen. The mtio of informosomes, free and incorporated into polyribosomes, was investigated following RNP-particles fractionation in a preformed CsCl gradient; the 6-methylthiouracil seed stimulation was shown to induce the development of an additional peak of synthetically active informosomes, their buoyant density being J.46 glcm . The 6-methylthiouracil stimulated seed germination causes a significant shortening of haricot plant ontogenesis period without any harmful changes of plant phenotype, the lutidine N-oxide stimulation leads, however, to deformed accelerated vegetative organ appearance accompanied byno reproductive organ development. Nature of 30 kDa protein as well as some problems concerning the correlation between different stimulator-induced cellular gene expression changes taking place during early postetnbryogenesis and further processes of haricot bean plant growth and development are discussed; some possible practical consequences of our experiments arc also mentioned.
Introduction.Due to vast biological screening we have earlier shown [1 ] such substances as lutidine N-oxide (LNO, ivin-yan) and 6-methylthiouracil (methyur, 6-MTU) accelerate sharply haricot bean seed ger mination.Our conviction is an embryonic axis of haricot bean plant (morpho-physiological and bio chemical characteristics of embryonic axis set, for mation and germination, its growth as well as deve lopment during embryogenesis and early postembryogenesis, i. e. during haricot bean seeds matu ration and germination were studied in detail [2][3][4]) to be a suitable model permitting to investigate several actual problems of plant physiology and biotechnology, namely: (i) to answer some questions concerning the mechanism of plant growth stimulator effect (these compounds are strongly different from natural plant hormones in their chemical structure), to understand if synthetic stimulators act through the cellular re ceptor systems similarly to plant hormones or interact directly with some target molecules on the level of cellular regulatory system (i.e. at the level of genetic control or phytohormonal regulation of plant growth and morphogenesis); Ш) to understand if the artificially stimulated plaint growth causes any harmful changes affecting the sequence of normal morphogenetical events during the early postembryogenesis (mature fully differentiated organs from primary non-differentiated embryonic axis organs -root, hypocotyl and leaf, beginning to form in this period) and if any drastic growth stimulation realized during the first developmental stages is able to impair the balanced growth and development of plant vegetative and reproductive organs during further plant ontogenesis stages (for example, acceleration of vegetative organ growth and inhibition set as well as formation of plant repro ductive organs).
To solve such problems as fully as possible we decided to get at first two principal goals: (i) to understand the mechanisms concerning the effect of two synthetic growth stimulators -6-MTU and LNO changing cellular gene expression in em bryonic axis cells at early postembryogenesis stage and programming plant growth and development; (a) to study the consequences of artificial haricot seed germination on following plant vegetation.
Materials and Methods.Seeds, In our expe riments seeds of haricot beans (Phaseolus vulgaris L.) of the variety «Bielozernaya» were used.Ethanolsterilized seeds were put for germination in a thermo stat at 26 °С; they were incubated between layers of filter paper moistened by distilled water or by 2 % solutions containing plant growth regulators.After the seed incubation, embryonic axes were separated from cotyledons, washed by distilled water and divided into three parts (each containing 100 axes) aimed for isolation of proteins, RNA, and RNP-particles.
Protein extraction.The tissue samples of em bryonic axes were frozen in liquid nitrogen and powdered carefully in a china mortar.10 volumes of preliminary cooled to 0 °С extracting buffer consisting of 30 mM tris-HCl, pH 8.7, 1 mM di thiothreitol (DTT), 1 mM ethylenediaminetetraacetic acid (disodium salt), 1 mM ascorbic acid, 5 rnM MgCl 2 , and 10 img polyvinylpyrrolidone were added to the tri turated material.The extract obtained v/as twice run (during 10 min and 15 min) in a centrifuge at 35.000 £.The 3/4 v acidified acetone (pH 4.5), containing 0.07 % 2-mercaptoethanol was added to supernatant fluid.This mixture was strongly shaken and incubated at -20 °С during 1 h.The denatured proteins were then pelleted by centrifugation at 35.000 g during 10 min.The pellets obtained were dried using a vacuum evaporator and dissolved in a buffer containing (50 jn) per I mg of dry precipitate): 8 M urea, 5 mM K 2 C0 3 , 0.5 % DTT, 2 % araphollynes solution -carrier ampholytes, their pH range being 3.5-9.5, 2 % Triton X-100 (MKSD-buffer).The soluble protein extract was separated from insoluble material by probes centrifugation (3 min at 15.000 g) and then kept at -20 °С until use.
Two-dimensional gel electrophoresis of proteins was realized according to the method described by O'Farrell [5] with several modifications.The protein fractionation in the first direction was made in a 5 % poly aery lamide laminar gel (C = 4 % w/w).The gel was polymerized in a 8 M urea solution supplemented by 2 % Triton X-100 and 2 % ampholines mixture (containing pharmalytes with pH ranges 3.5-9.5 and 5.0-7.0,their ratio being 3:1) to stabilize the central pH gradient zone.The gel was 1 mm wide, its size being 140 x 80 mm.0.02 M NaOH was used as a cathode electrode solution, and 0,01 M H 3 P0 4 was taken as an anode one.The gel pre-focusing was made at 400 V during 30 min.The protein elec trophoresis was realized during 2 h at 1200 V in a cooled chamber.A gel strip with marker proteins was cut out and stained for marking gel lanes, all other ones containing protein fractions were polymerized in a polyacrylamide gel with a 5-15 % concentration gradient to fractionate the proteins in the second direction realized in a buffer system described by Laemmli [6].This gel was 1.5 mm wide, its size being 145 x 145 mm.As an electrode buffer a tris-glycme solution (pH 8.3) supplemented with SDS was used.The proteins entered to the concentrating gel at 70 V during 1 h, the protein fractionation in a separating gel was run during 6 h at 160 V. Following separation the gel strips containing protein fractions were fixed by a mixture containing 30 % isopropanol and 20 % acetic acid and stained by a Coomassie brilliant blue solution.The stain excess was washed out by a mixture containing 5 % methanol and 7 % acetic acid.The gels stained were then photographed on a glass plate lit from the opposite side.
The isolation of total RNA preparations was realized after embryonic axis tissue destruction using a buffer solution (buffer I) containing 0.05 M tris-HCl, pH 7.6, 0.01 M MgCL, 0.06 M KC1, 1 % SDS, and 4 M guanidine isothiocyanate.The lysate ob tained was twice treated by a mixture of hot watersaturated phenol and chloroform; the RNA was pre cipitated from a water phase by ethanol, treated by proteinase K, deproteinized again by the same phe nol-chloroform mixture and precipitated by ethanol.Some polysaccharide contaminants present in RNA preparations (preventing fractionation molecular RNA and manifestation biological activity mRNA in vitro) were extracted by methoxyethanol; the RNA mole cules were then precipitated by cetylthrimethylammonium bromide; this last reagent was eliminated by multiple re-dissolving of RNA preparations in a 0.01 M sodium acetate solution followed by sodium acetate saturated ethanol precipitation.
Poly(A) + RNA separation from poly(A)~ RNA mo lecules was made using total RNA chromatography on the oligo(dT)-cellulose columns [7].Total RNA pre parations were analysed using electrophoresis in a 1.5 % agarose gel containing 7 M urea according to Locker [8 ]; the gels obtained had been saturated by ethidium bromide solution before RNA fractions pho tographing using an UV lamp.The poly(A) + RNA was analysed using a Northern-blot approach [91.cDNA was synthesized on poly(A) + RNA template according to the protocol described by Bueli et al. [10] using reverse transcriptase (revertase) and [a-32 P ]-containing deoxy-CTP as a label.A poly(A) + RNA pre paration was fractionated by electrophoresis in an agarose gel in the presence of formalyn; electrophoretically pure poly(A) + RNA fractions were trans ferred on nitrocellulose filters and hybridized with cDNA.The hybridization mixture contained 50 % formamide, 5X Upper buffer (pH 7.0), 5X Denhardt's solution [11], denatured calf thymus DNA (lOO^g/ml), poly(A)*RNA (1 //g/ml), 0.1 % SDS, and [a-32 P]-cDNA (1.5-10 8 cpm).Following hybridization, filters were carefully washed from exogenous label and exposed during 24 h to a film PM-1 with an accelerating screen (at -70 °С).The limits of poiy(A) + RNA sizes were evaluated according to radioautograph distribution of labelled po ly (A) + RNA-cDNA hybrids along the gel lanes (with regard to marker polynucleotides).
The experiments with polyfAf RNA translation were carried out in cell-free systems derived from wheat embryos [12] for quantitative determination incorporation of radioactive label into polypeptide material and rabbit reticulocytes [9 ] for definition fractional composition of full-length new synthesizing polypeptides, using [ 3 '*S [-methionine as a labelling compound.The polypeptides synthesized de novo in this last in vitro system were analyzed using the one-dimensional PAGE approach as mentioned above.The gels obtained were dried using a heating vacuumdryer («LKB», Sweden).The gel fluorography was made using a protocol described in [13], the gels having been saturated by a fluorescent reagent, 2,5-diphenyloxazole (PPO) [14].
Radioactive labelling of RNP-particles.The em bryonic axis samples (100 axes) were thoroughly washed by distilled water and incubated in a [ 3 H]uridine solution (3.7-10* Bq/ml) containing also pe nicillin and streptomycin (50 /ig/ml) to prevent the label incorporation by contaminating bacterial cells present in incubation mixture.The material was incubated during 1 h in a thermostat at 28 °С in a Petri dish and then washed by distilled water to remove all the non-incorporated label.
Isolation of labelled cytoplasmic RNP-particles.A sample of embryonic axis tissue was homogenized in the buffer II (containing 20 mM TEA-HC1, pH 7.6, 25 mM KC1, 3 mM MgCl 2 , 10 mM 2-mercaptoethanol, 250 mM sucrose, heparin (100 fig/ml) as an RNAse inhibitor, phenylmethylsulfonyl fluoride (50 /ug/ml) as a trypsin-like protease inhibitor, and cycloheximide (100 /ug/ml) as an inhibitor of mRNA trans location on cytoplasmic ribosomes, the corellation weighed tissue sample to volume of this buffer being 1:10.The homogenate obtained was then filtered and run at 18.000 g (20 min).A cytoplasmic postmitochondrial fraction was incubated with a 0.5 % Triton X-100 solution (20 min), layered on 0.5 ml 0.5 M sucrose, prepared on the buffer II solution containing no sucrose and centrifugated in a SW 60 Ті rotor (Beckman centrifuge L5-50) (3 h at 49.000 rpm).
Investigation of RNP-particles in a. CsCl density gradient.A pellet of cytoplasmic RNP-particles was suspended in the sucrose-free buffer II and divided by two; a half of this suspension was a control sample, its second portion was treated by a 15 mM EDTA-Na 2 solution to cause polyribosome disso ciation.Both preparations containing RNP-particles were then fixed (during 24 h) in a 4 % formaldehyde solution, all the aggregates formed being removed by pelleting at 10.000 g (10 min).The soluble material was then centrifuged in a preformed CsCl density gradient (1.33-1.65 g/cm 3 ) (12 h, 45.000 rpm, 2 °С) using the same SW 60 Ті rotor.
The fractions of this soluble material were then obtained using a siphon device; each fraction refrac tive index was determined and compared to density values of a calibration curve.The fraction optical density was taken in a spectrophotometer at 260 nm, Buoyant density (p) of RNP-particles in CsCl was calculated according to an equation given in [15]: p = D-10.8601-13.4979;D is a refractive index, the values 10.8601 and 13.4979 are experimentally found corrections ne cessary because of polarizing buffer properties.
Radioactivity of proteins and RNP fractions was determined in a LS 100C scintillation counter («Beckman») using Millipore AP-15 fibrous glass filters and scintillator dissolved in toluene.
Results and Discussion.While elaborating our approaches concerning mechanisms of action some synthetic compounds regulating the plant growth we took into account a lot of data suggesting the gene expression changes caused by phytohormones to belong to the principal mechanisms of plant growth and development [16][17][18] (however, the question concerning regulation expression of concrete genes by each from phytohormones are not yet correctly ans werable).We proposed that the synthetic stimulators of seed germination (similarly to natural plant hor mones) increasing drastically the embryonic organism size and its organ development, cannot mediate their action without some expression changes of genes coding synthesis of structural and functional proteins; the increasing of the pliant mass (by cell enlargement and cell division) being impossible-without intensive protein synthesis switching on a lot of reactions leading to cell and organ differentiation and spe cialization.
According to [19], the protein «spectrum» in any cell is to be changed during cell differentiation and specialisation, the protein synthesis process being a stage-and organospecific one.We proposed the protein assortment caused by any stimulated embryo growth (in view of accelerated development stages) is to be different from the assortment appeared in normally developed embryos during the same period; this difference was proposed to be nearly the same as between embryo protein «spectrum» determined at an car у and at a later postembryonic stages during natural plant development.
The main protein mass in eucaryotic cells is known to be presented by structural proteins and by enzymes of the main metabolic pathway (named also mu ticopied, constitutive, abundant or major pro teins), these compounds being present at all develop mental stages and detected without any difficulty using any one-dimensional gel electrophoresis ap proach.However, this approach does not permit to find «гаге» (so-called minor) stage-and organo specific enzymes and regulatory proteins, presented in some few copies and «hidden» on «one~dimen~ sional» electrophoregrams by major protein bands.So we fractionated a total protein preparation isolated from embryonic axes using a two-dimensional polyacrylamide gel electrophoresis (TD-PAGE) protocol.
The stained gel photographs obtained after our TD-PAGE experiment are present in the Fig. 1 (a, b,  c), the total protein preparations having been pre viously focused following the first one-dimensional separation according to their isoelectric point (pi) in a pH-gradienl gel.
Our results demonstrate the absence of any differences in embryonic axis protein preparations of haricot seeds after 12 h of postembryonic develop ment, both normal and LNO-stimuiated (Fig. 1, a  and b).Simultaneously, the 6-MTU-stimulated haricct bean germination causes the appearing of a

AN UNUSUAL MINOR PROTEIN APPEARING IN EMBRYONIC A;
Fig. 1.Two-dimensional polyacrylamide gel electrophoresis of < toplasraic proteins isolated from embryonic axis cells in 12 h post beginning of haricot bean seed germination; the proteins invesliga are taken from: a ---control (non-stimulated) seeds; /; -LN stimulated seeds; с -6-MTU-stimulated seeds «blurred-bordered» spot formed by an about 30 kl protein in a zone containing positively charged pi teins (Fig, 1, c).This spot (although of decreas intensity) is also seen in photographs obtained frc TD-PAGE after minimal quantities of total protc (4 jug per lane) having been loaded into gel pocket To determine this protein belonging to major minor ones, we realized in addition an experime with a one-dimensional PAGE approach in the pi sence of the SDS, total proteins of embryonic a> after 12 h of postembryonic development having be loaded on the gel.However, in this experiment failed to detect any separate band of the 30 ki protein or to find any staining band differences between control and 6-MTU-stimulated protein sam ples.So we concluded this protein to be a minor one, its blurred spot in the TD-PAGE permits to suppose it to be also a short-lived compound.This 30 kDa protein was not detected in embryonic axis pre parations in 24 h after the beginning of non-sti mulated germination process, the embryonic axis sizes being the same as their sizes in 6-MTUstimulated seeds in 12 h of postembryonic deve lopment (no photograph is presented).
The 30 kDa protein detected by the TD-PAGE approach appears only as a result of the 6-MTUstimulated seed germination, no its traces having been found both in control and LNO-stimulated samples; our aim was to gain some data explaining such results.Some physiological consequences of seed tre atment by LNO and 6-MTU are similar, the ger mination periods becoming twice shorter (and fi nishing in 2 days) with both stimulators.However, a lot of intracellular events followed by these substances treatment are to be quite different.There are some facts confirming this point of view.The LNO-treatment stimulates the total cellular protein synthesis proved in our one-dimensional electrophoresis ex periment using a 1 36 S J-methionine labelled in vivo total proteins isolated from embryonic axes and also following a gel fluorography approach [20 J.At the same time, the 6-MTU, according to our data, stimulates the only unusual 30 kDa protein synthesis.
To explain such a marked difference concerning the effect of two growth stimulating compounds, we suppose they action through different mechanisms influencing on certain stages of gene expression (transcription, formation of synthetically active RNP complexes, mRNA translation, etc.).The LNO was already proved to possess no action specificity on the level of gene expression regulation [20-221 acti vating both transcription and active RNP formation and increasing the synthesis of all the cellular pro teins without changing their assortment.
We thought the appearance of the 30 kDa protein «поп-typical» for a given developmental stage of embryonic axis cells might have been a result of some simultaneous changes at the translation level or at any precursor stage of the gene expression regulation (during transcription and/or transcript maturation levels).To answer this question, we realized some experiments concerning: 1) the comparative investigation of the LNO and 6-MTU effect on the translation process in an in vitro system of protein synthesis using a template of poly(A)*RNA as standard isolated from non-stimu lated embryonic axis cells; 2) the study of biological activities of po~ ly(A) + RNA preparations isolated from control em bryonic axes as well as from those ones stimulated and non-stimulated by LNO and 6-MTU using tin same in vitro system of protein synthesis; 3) the evaluation of activity protein-synthesizing apparatus (polyribosomes) in vivo, i. a. proportion of free and incorporated into polyribosomes (H-uridine labelling in vivo) of mRNP and rRNP-particles in embryo axis haricot bean seeds germinated withoul any treatment and following LNO and 6-MTU sti mulation.
In the Fig. 2 (a, b) the results of summary embryonic axes RNA preparations (using agarose gel electrophoresis) obtained with control and 6-MTU stimulated material; these data demonstrate the RNA preparations to contain non-degraded discrete frac tions of both high and low molecular masses (hnRNA including preRNAs, preRNAs «wasie products* origi nated due to processing rRNAs, mRNAs and 1RN As an d E 2( , 0 /E 230 for our preparations were > 2.0 and > 2.3, respectively, confirming a good degree of isolated RNA purification being practically free from protein and polysaccharide contaminations.We present also our electrophoregrams of a poly (A) " RNA preparation (Fig. 2, c) and of a poly(A)^RNA one (Fig. 2, d) demonstrating the rRNA to be practically absent.
In the Fig. 2 (e, f) our radioautographs are given obtained as a result of a Northern blot-hybridization procedure of poly (A)~RNA fractions with a [ 32 P J-cDNA preparation; our results demonstrate these fraction to contain highly heterogeneous poly(A) + RNA molecules of different molecular masses (due to differences the lengths of mRNA coding regions as well as of its regulatory ones, apparently); so there is no contradiction to other data [23] concerning the existence of a marked discretion (in the same size ranges) for eucaryotic mRNAs (from 8.0 up to 0.24 kbs); a series of spots fused along gel lanes can be seen on our photographs because of radioactive track autographs being overlapped on the X-ray film due to labelled highly heterogeneous hybrid mRNA-cDNA molecules localized on the filter too near from each other.An electrophoregram presenting marker poly nucleotides is also shown (see Fig. 2, g).So it is clear the poly (A ) + RNA preparations studied here to be non-degraded ones and to keep their high molecular components.
However, the principal nativity criterion for any poly (A) "RNA molecules is their messenger activity directing the polypeptide synthesis process in in vitro (cell-free systems); the evaluation of RNA messenger activity was a principal moment in our investigation.
In the Fig. 3 (a, b) the kinetics of [ 35 S]methionine incorporation into the TCA-insoluble ma terial is presented; these data were obtained in a well-known wheat embryo cell-free system using a template poly(A)"RNA as standard isolated from embryonic axes of non-stimulated haricot bean seeds.Our control data concerning TCA-insoluble fraction radioactivity were obtained with the same in vitro system containing no growth activator (see Fig. 3, a).We evaluated also the effect of the LNO and 6-MTU added to the incubated mixture (Fig. 3, b and c, respectively).We would like first of all to note the label incorporation increase during incubation in all the experiment materials (including also control ones) suggesting the nativity of poly(A) + RNA preparations used.Our second finding is that the 6-MTU inhibits slightly the level of protein label incorporation during all the incubation period comparing to the control incorporation level.On the contrary, the LNO sti mulates the poly (A)"RNA directed polypeptide syn thesis in our in vitro system, the synthesis level becoming almost twice higher.
Thus our results prove directly that the LNO activates the translation processes as well as the transcription one [20,21 ]; while the 6-MTU have no regulatory effect on this crucial stage of gene exp ression.
So it became of great interest to compare some functional properties of embryonic axes poly(A) + RNA preparations isolated from 6-MTU-stimulated and control haricot bean seeds.In the Fig. 4 (a, b) there are fluorograms demonstrating the PAGE distribution of polypeptide fractions.They had been previously labelled by [ 35 S ]-methionine in cell-free system from rabbit reticulocytes using of poly (A) "RNA as template RNAs isolated from embryonic axes of haricot been seeds following germination stimulated and nonstimulated by 6-MTU.The in vitro synthesized polypeptide fractions are very similar with both RNA preparations used with the only exception: an ad ditional polypeptide was detected in a gel zone of low molecular weight proteins while analyzing the labelled material from the incubation mixture containing the poly(A) 4 RNA preparation isolated from 6-MTU-stimuiated embryonic axes.Our data do not irrep roachably prove this additional peptide to be identical to the one detected in our previous in vivo studies.However, we have a fact of some 6-MTU-induced changes of an active poly(A) + RNA pool, i. e. of the 6-MTU participation in the regulatory transcription mechanisms.
However, contrary to in vitro experiments, any regulative events having taken place at the transcription level in vivo cannot be realized а і translation level because of several following cir cumstances: mRNA molecules exist and function in any plant cell as informosomes, i. e. mRN P-pai tides [24 ], no «naked» RNA is there present; at any stage of plant development there are bolh a reserved pool of functionally inactive mRNP being activated ai following stages and a pool of «working» mRNP taking part in the translation process.
The isolation of any poly (A) RNA preparation using phenol deproteinization of mRNP abolishes these mentioned above differences of mRNA pools, both types of them becoming equally able to be translated.So we needed to answer the question concerning the correlation between the appearance of the 30 kDa minor protein in vivo and the changes ai the translation level due to the 6-МTU-induced regulatory changes of transcription process.So we studied the correlation of active (incorporated into polyribosome complexes) and free, inactive in protein synthesis mRNPs in embryonic axis cells following stimulated and non-stimulated haricot bean seed germination.
The data concerning the CsCl gradient frac tionation of formaldehyde-fixed RNP-particles iso lated from stimulated and control seeds are given in the Fig. 5 ia-d).In both cases the obtained ra dioactive profiles of RNP-particles in the CsCl gra dient are presented by two radioactivity maxima, their densities being 1.39 and 1.42 g/cm\ respectively (small «peaks» of free informosomes), and two large peaks with their densities 1.52 g/cnr* (for the 6~ MTU-stimulated material) and 1.54 g/cm 1 (for the control sample), respectively, presenting de novo synthesized mRNP and rRNP-particles incorporated into polyribosomes.While EDTA treating of RNP preparations only a small part of radioactivity (fol lowing pulse RNP labelling during I h) remains in the region of ribosome subparticles localization, the main radioactive pool in both control and experimental samples being transported to I he region of free informosomes; its peak in control is localized ai 1.45 g/cm 3 ; however, the pulse-labelled RNPs of stimulated material form two peaks, the lesser one being concentrated in a region of the buoyant density l.39 g/cm 3 , the last main labelled material being found in a narrow de novo appeared peak at 1.46 g/cm 3 .
So we note a clear correlation between the 6-MTU-induced changes of transcription process as well as of poly (АГ RNA messenger activity (inducing the additional protein synthesis) influencing the qualitative changes of acting mRNPs (included into polyribosomes) and the appearance of the minor protein in embryonic axis cells in vivo; however, to prove the identity of protein molecules produced in vitro and in vivo, immunological approaches are necessary as well as the study of in vitro obtained protein fractions whose synthesis is directed by mRNAs isolated from polyribosomes.
It is also evident the changes being realized by synthetic plant growth activators on the gene exp ression level and triggering most probably the ac celeration of plant growth and development are to be a result of natural developmental process modi fications due to the activator effect.
Today two tightly interconnected forms of plant growth and regulation are known -genetic control and phytohormonal regulation; the results of their interaction may be summarized as follows: (i) the plant genome codes the synthesis of cellular constitutive (i.e. common for all the deve lopment stages) structural and.functional compounds as well as of stage-and organospecific ones to assure all the successive events of cell differentiation and specialization accompanying the formation of new tissues and organs; Ш) phytohormones being derivative of gene func tions (through a series of protein-enzyme molecules) as well as some other factors according to the feed-back regulation realize the re-programming of the cell genome by switching on and off conditionally «еагіу», «middie», and «late» genes [2.5] controlling the formation of stage-specific cell homeostasis and, besides, participating in the regulation of «peripheral» intracellular metabolic processes.
The question to be now answered is how the synthetic plant growth regulators are wedged (in scribed) in such a well-coordinated multi-step regu lation hierarchy?
This problem was earlier discussed in detail in our previous paper [1 ]; we propose that the synthetic compounds with their unusual structures having been never found in any plant cell are hardly able to realize their effect through the cell receptor system specific for a lot of natural compounds.It is more probably they mediate their effect by changing the active endogenic phytohormonal pool.An alternative explanation may also be proposed -a non-specific effect of growth regulators due to, apparently, of their higher binding (affinjty) with cellular effector systems (being their specific «binding sites» or «targets») realized more quickly comparing to natural phy tohormones, the last ones being forced out from their own receptors.The combined action of growth regu lators (observed in our experiments with the LNO) cannot be also ruled out; it may include a phytohormone-mediated effect at the transcription level and a direct regulator effect at the translation one (in addition to mentioned above the taking down of inhibitory action ABA by growth activators is pos sible) .
Discussing a possible 30 kE)a protein function one may suppose that the plants possess some genes coding some «obscure» protein products being nor mally absent; the promoters of these «silent», «cryptic», «hidden» genes («archaeological signs») are able [26 ), however, to be switched on by certain stress factors; in our experiment the 6-MTU was shown to be such a factor.We suppose that the 30 kDa protein is one from enzymes transforming the «unsuitable» («strange») for cells 6-MTU structure into a natural substance possessing a phytohormone activity; this phytohormone is able to accelerate drastically the plant cell growth by enlargement because in early postembryogenesis embryonic axis growth due to enlargement of hypocotyl.The «ephemeral» 30 kDa protein appears and disappears very quickly, ac cording to entering into cells and disappearance from cells the 6-MTU.The data of work [27 J witness in behalf of such possibility.Authors discovered the timing changes in enzymes synthesis in elicitortreated cell suspension cultures of Parsley.
It should be noted that this 30 kDa polypeptide is highly similar to polypeptide, forming the base of hydroxyproline-rich glycoprotein extensin (the mole cular mass of glycoprotein is 86 kDa, while its polypeptide without carbohydrate part forms precisely 30 kDa) [28][29][30], which is the major protein com ponents of the cell wall of dicotyledon plants.Ex tensin comprises 5-10 % from all proteins of cell wall and executes plural functions for cell.According with these works 30 kDa polypeptide is positively charged (pi of 9.9) and soluble in water medium precursor of extensin.This polypeptide is synthesised and glycosylated by posttranslational modifications in cytoplasm and then integrated into the cell wall space.The expression one of the extensin gene family (SbHRGP3) increases with seedling maturation, and its expression is relatively high in the mature regions of the hypocotyl and in the root of soybean seedlings (it is possibly that the intensification of expression some from extensin genes under the of 6-MTU stimulated haricot bean seed germination is noted).
The finale step of our work consisted of expe riments concerning the effects of the LNO and 6-MTU (possessing quite different mechanisms) on the following haricot bean ontogenesis.So the plants originated from germinated seeds (with or without growth stimulators) were cultivated further on the minimal nutrient media.It was shown the 6-MTUstimulation of seed germination to cause a significant plant development acceleration comparing to control plant ontogenesis duration (it is about 40 days in laboratory conditions); a plant originated from a 6-MTU-stimulated seed is able to complete its deve lopment in 25 days having passed all the ontogenesis steps including also flowering, ovary and even pod formation, its root network being also well developed (see Fig. 6, a> b).At the same time the LNO-induced seed germination leads to the plant growth defor mations -accelerated growth of stems carrying un derdeveloped foliage, no reproductive organs having been formed (not shown).
It is also noteworthy the similar effect of vege tative organs predominance is usually seen in plants growing on soils containing superfluous organic fer tilizers; the abundance of organic compounds is known to cause the nitrogen metabolism activation in plant cells, this process being somewhat analogous to the LNO-induced total protein synthesis.
It should be also taken into account the LNOinduced increased total protein synthesis and the 6-MTU-induced accelerated minor protein synthesis (these phenomena are somewhat similar to synthesis with protective functions of heat and cold shock proteins in plants to response on critical or extremely higin or low temperatures, respectively, for example [31 j) may be genetic «markcrs» determining the following plant development (vegetative organs pre dominance or complete although shortened onto genesis) already at the early postembryogenesis sta ge.
Concluding this paper we would like to note the selective 6-MTU-induced high level synthesis of the only minor protein suggests the gene coding this protein to belong to a family of unique genomic DNA sequences, its function being controlled by a strong promoter.The cloning of this markedly inducible promoter is to be perspective in the field of plant genetic engineering, namely, for recombinant gene constructions whose expression in transgenic plants is to be induced by 6-MTU.
Acknowledgement.Authors thank professor V. M. Kavsan for letting enzyme reverse transcriptase.

2 .
Agarose gel electrophoresis of RNA preparations isolated і'гош embryonic eell axes in 12 h post the beginning of haricot bean seed germination; a and b -total RNA preparations from control and 6-М'Ги-stimulated seeds, respectively; с and d -poly (A) RNA and poly(A) + RNA preparations, respectively, separated on an oligoidTr cellulose column; e and /-radioautographs of hybrid molecules containing [ 32 P]-cDNA and poly(A) + RNA fractions immobilized on nitrocellulose filter: poly(A) + RNA and | 3 'TJ cDNA isolated from embryonic axis cells of non-stimulated (e) and 6 MTU stimulated (/) haricot bean seeds, respectively; g electrophoretie distribution of marker polynucleotides on a parallel gel lane «mature» forms these RNAs of nuclear and cyto plasm, regulatory RNA molecules).The ratios E260/E2M

Fig. 3 .
Fig. 3. Kinetics of [ SI-methionine incorporation into the TCAinsoluble material in a wheat embryo in vitro system with using as template poly(A) + RNA: a-a control sample (no growth stimulators were used); b and с-label incorporation into peptides in the presence of the 6-MTU and LNO, respectively

Fig. 4 .
Fig. 4. Fluorographic analysis of electrophoretic polypeptide «spec-ІГШП» in the course of poly (A) + RNA-directed in vitro synthesis (rabbit reticulocyte cell-free system): polypeptide synthesis in the presence of poly (A)'RNA preparations from 6-MTU stimulated (a) and non-stimulated (/>) embryonic axis cells, respectively; с -label incorporation in vitro synthesized peptides in the absence of any added poly(A) T R.\A preparation (control sample)

Fig. 5 .
Fig. 5. Fractionation of RNP-particles in a CsCl density gradient: a and b -RNP-particle preparations from embryonic axes of MTL-stimulated seeds, untreated by EDTA and treated ones, respectively; с and d -RNP-particle preparations from embryonic axes of non-stimulated seeds, untreated by EDTA and treated ones, respectively

Fig. 6 .
Fig. 6.Plants grown from haricot bean seeds germinated without any stimulation (a) and following the 6-MTU directed stimulation (b)