Protein Patterns, Characterized by Computer Image Analysis, of Lentil Embryo Axes Germinating Under Salt Stress

Following 16, 40 and 64 h exposure to 0.33 M NaCl given after 8 h water imbibition, lentil seeds showed a gradual decrease of germination upon their transfer to water. These salt related changes were accompanied by modifications in the protein patterns of embryo axes as revealed by two-dimensional electrophoresis separation and by the computer image analysis of protein spots. In comparison with 8 h water imbibed seeds, prominent proteins comprised between the 5.1 – 7.6 pH isoelectric point in the first dimension and 75 – 50 kDa molecular mass in the second dimension showed a significant increase in their abundance as salt exposure increased. On transfer to water to complete germination, the content of many of these proteins decreased at 24h in 2 – 3 cm length embryo axes in comparison with the corresponding embryo axes of seeds continuously imbibed in water for 24 h. Some groups of proteins ranging between 15.5 – 17.3 kDa, already present after 8 h water imbibition, were not detectable after 24 h but were expressed in seeds exposed to NaCl and transferred to water for 24 h. Up- and down-regulated proteins in lentil embryo axes, imbibed under non-lethal salt stress conditions, have been tentatively identified by comparison with the protein map of germinating seeds of the model plant Arabidopsis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reactive oxygen species release, vitamin E, fatty acid and phytosterol contents of artificially aged radish (Raphanus sativus L.) seeds during germination

Seeds of Raphanus sativus L. subjected to accelerated ageing were investigated for reactive oxygen species (ROS) release and for content of vitamin E (tocopherol, TOC, and tocotrienol, TOC-3), fatty acids and phytosterols in seed coats, cotyledons and embryonic axes during germination. In unaged seeds, ROS release occurred mainly in seed coats of non-imbibed seeds and in seedlings (48?h of imbibition). TOC and TOC-3 were mainly represented by the ??-isoform, abundant in embryonic axes. Fatty acids were mainly found in cotyledons. In seed coat and embryonic axis, phytosterols consisted mainly of sitosterols. The effects of ageing were mainly visible in embryonic axes at 48?h of imbibition. Deterioration was associated with a decrease in fresh weight increase percentage, germination percentage, ??-TOC and total fatty acid content. An increase in ROS release from seed coats and in ??-TOC, ??-TOC, ??-TOC-3 content in embryonic axis was also observed. The use of ??-TOC and total fatty acids in embryonic axis as parameters of seed quality evaluation during storage was suggested.     

Patterns of protein synthesis during the germination of pea axes,and the effects of an interrupting desiccation period

As germination of axes of Pisum sativum L. seeds progressed, profound quantitative and qualitative changes occurred in the patterns of protein synthesis. This was shown by fluorography of gels following two-dimensional polyacrylamide gel electrophoresis separation of [³⁵S]methioninelabelled proteins. The effects of desiccation during germination on these in-vivo protein-synthesis patterns were followed. Desiccation differentially affected the synthesis of proteins. Usually, however, upon rehydration following desiccation the types of proteins being synthesized were recognizable as those synthesized earlier during imbibition of control, once-imbibed axes: seeds imbibed for 8 h, and then dried, did not recommence synthesis of proteins typical of 8-h-imbibed control seeds, but rather of 4-h-imbibed control seeds. Seeds imbibed for 12 h, and then dried and rehydrated, synthesized proteins typical of 4-h-and 8-h-control seeds. Thus drying of germinating pea axes caused the proteinsynthesizing mechanism to revert to producing proteins typical of earlier stages of imbibition. Drying during germination never caused the seed to revert to the metabolic status of the initial mature dry state, however.Abbreviation DR dried and rehydrated     

Osmoconditioning prevents the onset of microtubular cytoskeleton and activation of cell cycle and is detrimental for germination of Jatropha curcas L. seeds

• Jatropha curcas is an oilseed crop renowned for its tolerance to a diverse range of environmental stresses. In Brazil, this species is grown in semiarid regions where crop establishment requires a better understanding of the mechanisms underlying appropriate seed, seedling and plant behaviour under water restriction conditions. In this context, the objective of this study was to investigate the physiological and cytological profiles of J. curcas seeds in response to imbibition in water (control) and in polyethylene glycol solution (osmoticum).
• Seed germinability and reactivation of cell cycle events were assessed by means of different germination parameters and immunohistochemical detection of tubulin and microtubules, i.e. tubulin accumulation and microtubular cytoskeleton configurations in water imbibed seeds (control) and in seeds imbibed in the osmoticum.
• Immunohistochemical analysis revealed increasing accumulation of tubulin and appearance of microtubular cytoskeleton in seed embryo radicles imbibed in water from 48 h onwards. Mitotic microtubules were only visible in seeds imbibed in water, after radicle protrusion, as an indication of cell cycle reactivation and cell proliferation, with subsequent root development. Imbibition in osmoticum prevented accumulation of microtubules, i.e. activation of cell cycle, therefore germination could not be resumed.
• Osmoconditioned seeds were able to survive re‐drying and could resume germination after re‐imbibition in water, however, with lower germination performance, possibly due to acquisition of secondary dormancy. This study provides important insights into understanding of the physiological aspects of J. curcas seed germination in response to water restriction conditions.

     

Differential response of antioxidative enzymes in embryonic axes and cotyledons of germinating lupine seeds

Germination of lupine (Lupinus luteus L.) seeds was accompanied by an increase in concentration of free radicals with g ₁ and g ₂ values of 2.0056 ± 0.0003 and 2.0033 ± 0.0005, respectively. The highest intensity of free radical signal was observed in embryo axes immediately after radicle protruded through the seed coat. Hydrogen peroxide accumulated in embryonic axes and cotyledons during imbibition before the onset of germination in the seed population. The activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) rose progressively in embryo axes. In cotyledons SOD activity did not change significantly, while that of CAT increased during germination. The enhancement of Cu, Zn-SODs and Mn-SOD isoforms in embryonic axes was observed. A new isoform of catalase was synthesized, suggesting that it plays a relevant role during germination. SOD and CAT activities were detected in dry seeds. Free radical generation and response of antioxidative enzymes differed between embryo axes and cotyledons during the germination timecourse.     

Mechanism of seed priming in circumventing thermodormancy in lettuce

Lettuce (Lactuca sativa L. cv Minetto) seeds were primed in aerated solutions of 1% K₃PO₄ or water at 15°C in the dark for various periods of time to determine the manner by which seed priming bypasses thermodormancy. Seeds which were not primed did not germinate at 35°C, whereas those which were primed for 20 h in 1% K₃PO₄ or distilled H₂O had up to 86% germination. The rate of water uptake and respiration during priming were similar regardless of soak solution. Cell elongation occurred in both water and 1% K₃PO₄, 4 to 6 h prior to cell division. Both processes commenced sooner in water than K₃PO₄. Radicle protrusion (germination) occurred in the priming solution at 21 h in water and 27 h in 1% K₃PO₄.

Respiration, radicle protrusion and cell division consistently occurred sooner in primed (redried) seeds compared to nonprimed seeds when they were imbibed at 25°C. Cell division and elongation commenced after 10 h imbibition in primed (redried) seeds imbibed at 35°C. Neither process occurred in nonprimed seeds. Respiratory rates were higher in both primed and nonprimed seeds imbibed at 35°C compared to those imbibed at 25°C, although radicle protrusion did not occur in nonprimed seeds which were imbibed at 35°C. It is apparent that cell elongation and division are inhibited during high temperature imbibition in nonprimed lettuce seeds. Seed priming appears to lead to the irreversible initiation of cell elongation, thus overcoming thermodormancy.

     

The Multiple Forms of alpha-Amylase Enzyme of the Araucaria Species of South America: A. araucana (Mol.) Koch and A. angustifolia (Bert.) O. Kutz : A Comparative Study

α-Amylase is one of the major enzymes present in the seeds of both Araucaria species of South America and it initiates starch hydrolysis during germination and early seedling growth. The pattern of the multiple forms of α-amylase of the two Araucaria species was investigated by electrophoresis and isoelectrofocusing of the native enzyme in polyacrylamide gels. The enzyme forms were compared in the embryo and megagametophyte of quiescent seeds and of seeds imbibed for 18, 48, and 90 hours. Specific α-amylase enzyme forms appear and disappear during these imbibition periods showing both similarities and differences between tissues and species. Before imbibition, there are five α-amylase forms identical in both tissues, but different between species. After 18 hours of imbibition, there are two enzyme forms in both tissues of Araucaria araucana seeds, only one form in the embryo of Araucaria angustifolia but two forms in the megagametophyte of this specie. After 48 hours of seed imbibition, most of the enzyme forms present in quiescent seeds reappear. At 90 hours of imbibition different enzyme forms are detected in the embryo with respect to the gametophyte. The changes in form patterns of α-amylase are discussed according to a possible regulation of gene expression by endogenous gibberellins.     

Prior hydration of Brassica tournefortii seeds reduces the stimulatory effect of karrikinolide on germination and increases seed sensitivity to abscisic acid

Background and Aims

The smoke-derived compound karrikinolide (KAR₁) shows significant potential as a trigger for the synchronous germination of seeds in a variety of plant-management contexts, from weed seeds in paddocks, to native seeds when restoring degraded lands. Understanding how KAR₁ interacts with seed physiology is a necessary precursor to the development of the compound as an efficient and effective management tool. This study tested the ability of KAR₁ to stimulate germination of seeds of the global agronomic weed Brassica tournefortii, at different hydration states, to gain insight into how the timing of KAR₁ applications in the field should be managed relative to rain events.

Methods

Seeds of B. tournefortii were brought to five different hydration states [equilibrated at 15 % relative humidity (RH), 47 % RH, 96 % RH, fully imbibed, or re-dried to 15 % RH following maximum imbibition] then exposed to 1 nm or 1 µm KAR₁ for one of five durations (3 min, 1 h, 24 h, 14 d or no exposure).

Key Results

Dry seeds with no history of imbibition were the most sensitive to KAR₁; sensitivity was lower in seeds that were fully imbibed or fully imbibed then re-dried. In addition, reduced sensitivity to KAR₁ was associated with an increased sensitivity to exogenously applied abscisic acid (ABA).

Conclusions

Seed water content and history of imbibition were found to significantly influence whether seeds germinate in response to KAR₁. To optimize the germination response of seeds, KAR₁ should be applied to dry seeds, when sensitivity to ABA is minimized.     

Protein Synthesis in Dormant and Non-Dormant Cocklebur Seed Segments

Using the axial and cotyledonary segments of lower cocklebur (Xanthium pensylvanicum Wallr.) seeds, protein synthesis as shown by incorporation of radioactive leucine was examined in relation to their dormant status. During the first 9 h of water imbibition, the protein synthesis was higher in the dormant axes than in the non-dormant, after- ripened ones. When imbibed for more than 12 h non-dormant axes had a higher activity than dormant ones. This was also the case with the cotyledonary segments. Cyctoheximide, an inhibitor of protein synthesis, blocked protein synthesis in the axial tissue regardless of its dormant status, and thereby inhibited germination of the non-dormant seeds. In the dormant seeds, however, cycloheximide at 3 mM slightly stimulated germination without stimulating the C₂H₄ production. Based on these results, it is suggested that in cocklebur seeds there may be some proteinaceous system which is involved in the maintenance of dormancy.     

Water Relations of Seed Development and Germination in Muskmelon (Cucumis melo L.) : V. Water Relations of Imbibition and Germination

The initiation of radicle growth during seed germination may be driven by solute accumulation and increased turgor pressure, by cell wall relaxation, or by weakening of tissues surrounding the embryo. To investigate these possibilities, imbibition kinetics, water contents, and water (Ψ) and solute (ψ_s) potentials of intact muskmelon (Cucumis melo L.) seeds, decoated seeds (testa removed, but a thin perisperm/endosperm envelope remains around the embryo), and isolated cotyledons and embryonic axes were measured. Cotyledons and embryonic axes excised and imbibed as isolated tissues attained water contents 25 and 50% greater, respectively, than the same tissues hydrated within intact seeds. The effect of the testa and perisperm on embryo water content was due to mechanical restriction of embryo swelling and not to impermeability to water. The Ψ and ψ_s of embryo tissues were measured by psychrometry after excision from imbibed intact seeds. For intact or decoated seeds and excised cotyledons, Ψ values were >−0.2 MPa just prior to radicle emergence. The Ψ of excised embryonic axes, however, averaged only −0.6 MPa over the same period. The embryonic axis apparently is mechanically constrained within the testa/perisperm, increasing its total pressure potential until axis Ψ is in equilibrium with cotyledon Ψ, but reducing its water content and resulting in a low Ψ when the constraint is removed. There was no evidence of decreasing ψ_s or increasing turgor pressure (Ψ-ψ_s) prior to radicle growth for either intact seeds or excised tissues. Given the low relative water content of the axes within intact seeds, cell wall relaxation would be ineffective in creating a Ψ gradient for water uptake. Rather, axis growth may be initiated by weakening of the perisperm, thus releasing the external pressure and creating a Ψ gradient for water uptake into the axis. The perisperm envelope contains a cap of small, thin-walled endosperm cells adjacent to the radicle tip. We hypothesize that weakening or separation of cells in this region could initiate radicle expansion.     

Effect of Combined Salt and Heat Treatments on Germination and Heat-Shock Protein Synthesis in Lentil Seeds

The germination of lentil seeds was gradually reduced when seeds were exposed to temperature of 30 or 40 °C, either alone or combined with 0.1, 0.2 or 0.3 M NaCl or 34.1 % (m/v) PEG 8000, during 6 –12 h imbibition. [³⁵S]-methionine incorporation in 12 h imbibed lentil axes also decreased with increasing NaCl concentration at 20 and 40 °C, whereas at 30 °C only 0.3 M NaCl treatment partially inhibited protein synthesis. An analysis of newly synthesized proteins by 1-D SDS PAGE, showed that the expression of most polypeptides decreased following increasing stress. Among these, low molecular mass heat-shock proteins declining, higher in 40 °C treated axes than those treated at 30 °C, supports the hypothesis that at this temperature maximal level of expression of these proteins was achieved.     

Physiological characteristics and related gene expression of after‐ripening on seed dormancy release in rice

After‐ripening is a common method used for dormancy release in rice. In this study, the rice variety Jiucaiqing (Oryza sativa L. subsp. japonica) was used to determine dormancy release following different after‐ripening times (1, 2 and 3 months). Germination speed, germination percentage and seedling emergence increased with after‐ripening; more than 95% germination and 85% seedling emergence were observed following 1 month of after‐ripening within 10 days of imbibition, compared with <45% germination and 20% seedling emergence in freshly harvested seed. Hence, 3 months of after‐ripening could be considered a suitable treatment period for rice dormancy release. Dormancy release by after‐ripening is mainly correlated with a rapid decline in ABA content and increase in IAA content during imbibition. Subsequently, GA₁/ABA, GA₇/ABA, GA₁₂/ABA, GA₂₀/ABA and IAA/ABA ratios significantly increased, while GA₃/ABA, GA₄/ABA and GAs/IAA ratio significantly decreased in imbibed seeds following 3 months of after‐ripening, thereby altering α‐amylase activity during seed germination. Peak α‐amylase activity occurred at an earlier germination stage in after‐ripened seeds than in freshly harvested seeds. Expression of ABA, GA and IAA metabolism genes and dormancy‐related genes was regulated by after‐ripening time upon imbibition. Expression of OsCYP707A5, OsGA2ox1, OsGA2ox2, OsGA2ox3, OsILR1, OsGH3‐2, qLTG3‐1 and OsVP1 increased, while expression of Sdr4 decreased in imbibed seeds following 3 months of after‐ripening. Dormancy release through after‐ripening might be involved in weakening tissues covering the embryo via qLTG3‐1 and decreased ABA signalling and sensitivity via Sdr4 and OsVP1.     

Phytochrome-mediated changes in the ATP content of Kalanchoë blossfeldiana seeds

One short red (R) irradiation increases the ATP content of Kalanchoë blossfeldiana Poelln. cv Feuerblüte seeds before onset of germination. Phytochrome control is demonstrated by the full R/far-red light (FR) reversibility of the effect in water imbibed seeds. In seeds imbibed in the presence of gibberellin A₃ (GA₃, one short R exposure already increases the ATP content when given 2h after start of imbibition, showing phytochrome control at the energy-metabolic level when one R pulse cannot yet induce germination. After longer imbibition periods in the presence of GA₃, one short FR irradiation also increases the ATP content of ungerminated Kalanchoë seeds. The time course of the ATP levels after a R or FR germination inducing irradiation shows an initial increase that clearly preceeds germination. A second increase starts about 15 h after irradiation and is most probably the consequence of the germination itself. The results suggest that, in Kalanchoë seeds, the increase in ATP levels, induced by irradiation(s) and preceding germination, is a phytochrome-mediated process, supplying energy, required for germination.     

Differential response of PCNA and Cdk-A proteins and associated kinase activities to benzyladenine and abscisic acid during maize seed germination

The proliferating cell nuclear antigen (PCNA) is a protein factor required for processive DNA synthesis that is associated with G(1) cell cycle proteins. It has been demonstrated previously that, in germinating maize (Zea mays) embryonic axes, PCNA forms protein complexes with two Cdk-A proteins (32 and 36 kDa) and with a putative D-type cyclin. These complexes exhibit protein kinase activity on histone H1 and on the maize homologue of the pRB (retinoblastoma) protein. Flow cytometry has been used to study the influence of the phytohormones benzyladenine (BA) and abscisic acid (ABA) on cell cycle advancement during maize germination. It was found that, while BA accelerates the passage of cells from G(1) to G(2), ABA delays cell cycle events so that most cells seem to remain in G(1). The amounts of PCNA and Cdk-A proteins also vary according to the hormone treatment. In embryonic axes, PCNA increases rapidly during early germination in BA, compared with a gradual increase in water, while ABA treatment had only a marginal effect. However, of the two Cdk-A proteins, the 32 kDa protein is strongly reduced after 15 h of imbibition in water while this occurs later when axes are imbibed in BA or ABA. The PCNA-associated protein kinase activity in the BA and ABA treatments falls after 3 h of imbibition compared with activity in the control; however, while kinase activity in the BA treatment continues to decline during imbibition, it remains relatively constant until 24 h of imbibition in the ABA treatment. By contrast, a p13(Suc1)-associated Cdk-A kinase is activated after 15 h of imbibition under all treatments, particularly in ABA. These results suggest that, in maize, ABA delays the germination process by affecting cell cycle advancement, stopping cells mostly in a G(1) state.     

The Effect of Changing Temperatures During Imbibition on Ultrastructure in Germinating Pea Embryonic Radicles

Hodson, M. J., Di Nola, L. and Mayer, A. M. 1987. The effectof changing temperatures during imbibition on ultrastructurein germinating pea embryonic radicles.—J. exp. Bot. 38:525–534. Pea seeds were imbibed at 5 °C or at 25 °C for 5–6h and then germinated at the same temperature or transferredto the other temperature for 15 h. After imbibition or germinationthe embryonic axis was removed, fixed and the ultrastructureof the radicle tip examined. Exposure of the seeds to 5 °Cduring imbibition resulted in the cessation of almost all ultrastructuralchanges during subsequent germination at 5 °C. When theseeds were transferred to 25 °C development of ultrastructurewas far slower than expected. In particular, mitochondrial structurefailed to develop, there were few Golgi and little ER, and lipidbodies located near the plasma membrane disappeared or fusedmuch more slowly with the membrane. An attempt is made to relatethe observations on ultrastructure with data previously reportedon the metabolism of phospholipids in the plasma membrane andER of the embryonic axis. A tentative hypothesis to accountfor the effect of temperature of imbibition on subsequent seedgermination is proposed. Key words: Pisum sativum L. cv. Alaska, germination, imbibition, temperature, ultrastructure, lipid bodies, protein bodies, vacuolation, mitochondria     

Association of DNA biosynthesis with planting value enhancement in hydroprimed maize seeds

Inadequate plant stand establishment due to insufficient germination is an important bottleneck in achieving the potential yields, specifically under uncertain growing conditions. Hydropriming has been publicized as a useful tool to alleviate the stress-induced consequences. Association of DNA biosynthesis in hydroprimed seeds of maize; hybrid, PEHM 5 and its parental lines (CM150 and CM151) was studied. Seeds were hydroprimed at 25 °C for 30 h and half of them were surface dried while the other half were redried back to the original moisture contents. The treated and untreated seeds were evaluated for; germination test, mean germination time, vigour index and DNA levels in embryos of fully matured seeds. Both the treatment strategies significantly enhanced the planting value of maize seeds. Vigour index I revealed significant correlation with G2/G1 ratio whereas significant negative correlation between G2/G1 ratio and mean germination time was observed. Large amounts of 2C DNA signals in flow cytometric analysis divulged that most cells might had arrested in the cell cycle at the pre synthetic G1 phase of nuclear division. Augmentation of 4C signal in the embryonic region was noticed after imbibition that could be ascribed to cells entering the synthetic phase of nuclear division. The embryonic cells showed increased 4C:2C ratios after 30 h of imbibition. Apparently, DNA synthesis preceded germination. In dry seeds, DNA histograms revealed both a 2C signal and a considerable 4C peak. A priming period of 30 h in distilled water considerably enhanced the rate and uniformity of germination in both surface dried and redried treatment strategies. Upon priming, the ratio of 4C:2C increased during the 30 h priming period, though the level in case of redried seeds did not reach the level obtained after hydration in water without drying back. However, the 4C: 2C ratio was constant after redrying the seeds to the original moisture content, indicating that the chromosomal material in the embryonic cells had stably ceased cell cycle activity at the G2 phase. The present results indicate that the beneficial effects of priming on seedling performance could be associated with the action of replicative DNA synthesis processes prior to germination.     

Spectrophotometric characterization of phytochromes in dimorphic cocklebur seeds in relation to capacity for germination

Phytochrome was measured spectrophotometrically in different tissues of the upper (positively photoblastic) and lower (negatively photoblastic) seeds of the cocklebur (Xanthium pennsylvanicum Wallr.). Axial parts of the seeds, in particular parts of the radicle, contained high levels of phytochrome, while cotyledonary parts contained only low levels. These results were consistent with the distribution of the light-sensitive areas of the seeds that were associated with germination. Phytochrome levels in both types of dimorphic seeds increased gradually with increasing duration of dark imbibition for 4–8 h, then the rates of increase in levels of phytochrome accelerated. In both types of seed, some phytochrome was measurable even before imbibition. In the lower seeds, up to 20% of the phytochrome was occasionally observed as P_fr in samples imbibed in darkness for a short time (up to 12 h). A slight blue shift of the peak of P_T in the difference spectrum of phytochrome was observed in the case of lower seeds imbibed for 0–2 h. These results suggest that, to some extent, the lower axes contain dehydrated P_fr or intermediate(s) in the photoconversion of phytochrome. The dark reactions of P_fr were also examined in excised axes of both types of dimorphic seed after they had been pre-imbibed for 16 h in darkness. Dark destruction of P_fr was observed in both types of seed. In addition, net increases in levels of P_r were observed in the dark controls and in the samples irradiated with red light after the level of P_fr diminished. No ‘inverse’ dark reversion from P_r to P_fr was detected. Thus, after 16 h of imbibition, there were no differences in terms of properties of phytochrome between the two types of seed, and the different responses to light of upper and lower seeds might depend mainly on a difference in the physiological state of the two types of seed rather than the properties of phytochrome.     

Differential tissue-specific expression of cysteine proteinases forms the basis for the fine-tuned mobilization of storage globulin during and after germination in legume seeds

The temporal and spatial distribution of cysteine proteinases (CPRs) was analyzed immunologically and by in situ hybridization to identify the CPRs involved in the initiation of storage-globulin degradation in embryonic axes and cotyledons of germinating vetch (Vicia sativa L.). At the start of germination several CPRs were found in protein bodies in which they might have been stored in the mature seeds. Cysteine proteinase 1 was predominantly found in organs like the radicle, which first start to grow during germination. Cysteine proteinase 2 was also present at the start of germination but displayed a less-specific histological pattern. Proteinase B was involved in the globulin degradation of vetch cotyledons as well. The histological pattern of CPRs followed the distribution of their corresponding mRNAs. The latter were usually detected earlier than the CPRs but the in situ hybridization signals were histologically not as restricted as the immunosignals. Proteolytic activity started in the radicle of the embryonic axis early during germination. Within 24 h after imbibition it had also spread throughout the whole shoot. At the end of germination, newly synthesized CPRs might have supplemented the early detectable CPRs in the axis. In the cotyledons, only the abaxial epidermis and the procambial strands showed proteinase localization during germination. Both CPR1 and CPR2, as well as the less common proteinase B, might have been present as stored proteinases. Three days after imbibition, proteolytic activity had proceeded from the cotyledonary epidermis towards the vascular strands deeper inside the cotyledons. The histochemical detection of the CPRs was in accordance with the previously described histological pattern of globulin mobilization in germinating vetch [Tiedemann J, et al. (2000)]. A similar link between the distribution of CPRs and globulin degradation was found in germinating seeds of Phaseolus vulgaris L. The coincidence of the histological patterns of globulin breakdown with that of the CPRs indicates that at least CPR1, CPR2 and proteinase B are responsible for bulk globulin mobilization in the seeds of the two legumes. Received: 14 February 2000 / Accepted: 16 August 2000