Germination of seeds of annual and biennial celery (Apium graveolens)

Seeds of 4 annual cultivars of celery ( Apium graveolens L. No. 15, 16, 17 and 143) were able to germinate in the dark, under high temperature, in relatively high concentrations of NaCl solutions and in the presence of relatively high concentrations of the inhibitors of the biosynthesis of gibberellin, paclobutrazol and ancymidol. Seeds of two biennial cultivars [Florida and Earlibell (EB)] showed very low germinability, or failed to germinate under the same conditions. These results are discussed in terms of endogenous gibberellin levels, which may be higher in the seeds of annual cultivars as compared to biennial ones.     

Comparative studies of sucrose and mannitol utilization in celery (Apium graveolens)

Utilization of sucrose and mannitol, the major forms of translocatable assimilate in celery ( Apium graveolens L. cv. Giant Pascal), was investigated in intact plants, excised leaves and leaf discs by estimating the soluble carbohydrate pools, starch levels and oxidation of [¹⁴C]-sucrose or mannitol in the light and after extended dark treatments. In detached mature fully-expanded leaves, mannitol pools remained constant, while sucrose decreased during a 48 h dark treatment. In attached leaves on plants trimmed to a single compound leaf, however, mannitol levels decreased after a dark treatment. In leaf discs floated on bathing solutions containing [¹⁴C]-sucrose or [¹⁴C]-mannitol, oxidation of mannitol was restricted to young leaf tissues, whereas sucrose was metabolized to CO₂ regardless of leaf age. Uptake of labelled mannitol, however, was greater than that of sucrose in the light in leaves of every age. Although both mannitol and sucrose are translocated out of leaf tissues, leaf age differences indicate that, unlike sucrose, mannitol utilization is restricted to active sink tissues. The results suggest different roles for mannitol and sucrose with mannitol representing a more rigorously sequestered transport carbohydrate.     

Mannitol-enhanced, fluid-phase endocytosis in storage parenchyma cells of celery (Apium graveolens; Apiaceae) petioles

We recently demonstrated the occurrence of a sucrose-enhanced, fluid-phase endocytic (FPE) mechanism of nutrient uptake in heterotrophic cells. In the present work, the possible enhancement/induction of FPE by photoassimilates other than sucrose was investigated by measuring the incorporation of the fluorescent endocytosis marker d-TR (dextran-Texas red, 3000 mw) into celery (Apium graveolens) petiole storage parenchyma (CSP), a tissue that transports and accumulates mannitol. Mannitol uptake in these cells is biphasic, with a hyperbolic phase at concentrations below 20 mM and a linear phase above 20 mM external solute concentration. In the absence of mannitol, or in its presence at concentrations within the hyperbolic phase, CSP cells accumulated low levels of d-TR. Conversely, d-TR accumulation by CSP cells was greatly enhanced in the presence of mannitol at concentrations within the linear phase. At high external mannitol concentration, d-TR accumulation was prevented by the endocytic inhibitors LY294002 and latrunculin B. In addition, d-TR uptake was temperature dependent under high mannitol concentration. Microscopic observations revealed that d-TR accumulated in the vacuole. These data support the occurrence of an FPE mechanism in CSP cells that participates in trapping and transport of photoassimilates to the vacuole. The FPE mechanism is enhanced by high mannitol concentrations.     

The consequences of an unusual Robertsonian translocation in celery (Apium graveolens var dulce)

A Robertsonian translocation found in a cultivar of celery is described which is unusual because half the small product of the exchange survives as a telocentric chromosome. The change has no drastic effect on the overall fitness of the translocation homozygote. The consequences of such a change for karyotype evolution are shown to be, karyotype asymmetry, the possible genesis of B-chromosomes and the possibility of a chromosome change becoming established even though it has no adaptive value.     

Growth regulatory effect of three benzimidazole fungicides on the germination of celery (Apium graveolens) seeds

Seeds of four celery cultivars did not germinate when incubated in buffered solutions in the dark at 22 °C. This high-temperature-induced dormancy was broken with either of the systemic fungicides benomyl or BAS 3460 F (mainly methyl-2-benzimidazole carbamate) when used in combination with a mixture of the gibberellins A₄ and A₇ (GA_4/7). The fungicide thiabendazole was ineffective in these tests.     

The origin of variation in seed density in celery (Apium graveolens L.)

Seeds were harvested separately from the sequentially formed umbels to obtain information about the origin of variation in seed density in celery. The study involved seeds from the lowest order (primary) to the highest order (quarternary) umbels from the cvs Mars, Monarch, Selfira and Tall Utah. With increasing umbel order the percentage germination decreased and the mean germination time increased. Seed density increased with increasing umbel order, but was more highly correlated with the length of the seed ripening period which differed for each umbel order due to simultaneous harvesting. The decrease in seed density during seed development was correlated with an increase in air volume in the seeds. It is concluded that the variation in seed density in celery seed lots originated from differences in seed maturity.     

Gibberellin involvement in dormancy-break and germination of seeds of celery (Apium graveolens L.)

The temperature-dependent, primary dormancy of cv. Florida 683 celery seeds in darkness was partially broken by a 30 min light exposure on the third day of incubation at 20–22°C, resulting in c 50 percent germination after 20 days. This light stimulation was negated by including different inhibitors of gibberellin biosynthesis in the incubation medium. Subsequent addition of a solution of the gibberellins A₄ and A₇ or of the gibberellin-active compound (1-3-chlorophthalimido)-cyclohexane carboxamide (AC94,377) overcame the inhibitory effects on germination of these GA-biosynthesis inhibitors. It is suggested that light stimulates the biosynthesis of gibberellins which are essential for dormancy-break in celery seeds and that this biosynthesis is either directly or indirectly controlled through phytochrome.Abbreviations AC94,377 1-(3-chlorophthalimido)-cyclohexane carboxamide; ancymidol, -cyclopropyl--(4-methoxyphenyl)-5-pyrimidinemethanol - AMO1618 N,N,N-2-tetramethyl-5-(1-methyl ethyl)-4-(1-piperidinylcarbonyl)oxy-benzenaminium chloride - BTS44584 S-2,5-dimethyl-4-pentamethylenecarbamoyloxyphenyl-SS-dimethyl sulphonium - P toluenesulphonate; chlormequat chloride, 2-chloroethyltrimethylammonium chloride; daminozide - N dimethylaminoscuccinamic acid; paclobutrazol, (2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl pentan-3-ol)     

Regeneration of plantlets from celery (Apium graveolens L.) callus using a fermentor

The efficiency of somatic embryogenesis of calluses induced from celery (Apium graveolens L.) (F1 variety, 1026-2) in an air-lift type fermentor was about half of that in flasks. The efficiency of somatic embryo maturation in an air-lift type fermentor was almost the same as that in flasks, and the efficiency in a stirred-tank type fermentor was about 70% of that in an air-lift type. We succeeded in producing 1,590,000 somatic embryos, and 296,000 plantlets after maturation by batch culture using a 30-l air-lift type fermentor.     

The effect of temperature on the germination-promoting activities of cytokinin and gibberellin applied to celery seeds (Apium graveolens)

Celery seeds (Apium graveolens L. cv. Lathom Blanching) made dormant by high temperature pretreatment (28–40°C) during imbibition in the dark, germinated at 22°C in the light after treatment with benzyladenine (BA). This BA-induced promotion of germination increased with increasing pre-treatment temperature from 32 to 38°C. whether BA was given before or after pretreatment. A mixture of gibberellins A₄ and A₇ (GA_4/7) given before a 4 day high temperature pretreatment at 32°C partially inhibited the germination-promoting activity of GA_4/7 given after. It is suggested that gibberellin induces the formation of a thermola-bile product which is necessary for germination, the precursor of which has a limited source.     

Overwintering and growth regulator treatment effects on celery (Apium graveolens L.) flowering and seed production

Celery (Apium graveolens L.) plants cv. Jason overwintered in a polythene tunnel flowered earlier and grew taller than similar plants given a 10-week cold-treatment at 5°C prior to transplanting in the same tunnel in mid-February. However, there was no significant difference in the yield of seeds obtained from both treatments, plants grown at a density of 4m^-2 yielded less seeds than those at 2m^-2, though the yield per unit area was slightly higher from the high density treatment. Treatment with 100 mgl^-1 GA₃ applied twice just prior to flowering and during anthesis increased flower stalk, flower pedicel and stamen length but delayed flower opening and seed ripening and decreased seed set and seed yield. Treatment with a mixture of 1000 mgl^-1 GA₄ and GA₇ plus 1000 mgl^-1 ethephon on three occasions during seed ripening decreased seed yield and reduced seed germination though those seeds capable of germinating were less dormant than seeds from untreated plants. The size distribution of seeds was unaffected by any treatment other than the preseeding spray with GA₃ which reduced the percentage of medium-size seeds.     

Turnover of cell-wall polysaccharides during somatic embryogenesis and development of celery (Apium graveolens L.)

Non-embryogenic cells (NEC) and embryogenc cells (EC) were separated from cell clusters derived from the hypocotyl segments of celery seedlings, which had been suspension-cultured in MS medium supplemented with 10⁵ M 2,4-D. The EC formed globular embryos in medium without 2,4-D. The globular embryo developed through heart-shaped, torpedo to cotyledonary embryos within 10 days. The EC and developing embryos were fractionated into symplastic [MeOH, hot water (HW), starch (S)] and apoplastic [pectin, hemicellulose, TFA (trifluoroacetic acid)-soluble and cellulose] fractions. The EC contained lower levels of sugar in the MeOH fraction and higher levels of starch than NEC. In the apoplastic fractions, there were no differences of total sugar amounts between NEC and EC. Cellulose contents were about 10% of the wall polysaccharides. During somatic embryogenesis, total sugar contents of the MeOH and HW fractions increased till the heart-shaped embryo stage, and then decreased during the torpedo and cotyledonary embryo stages. The sugar contents of the starch, pectin, TFA-soluble, and cellulose fractions did not change during the stages mentioned above. However, the hemicellulose substances remarkably increased during embryogenesis, and then decreased as the development proceeded. The neutral sugar components of the hemicellulosic fractions were analyzed. Arabinose increased markedly in EC to the globular embryo stage, but decreased as the development proceeded. Galactose increased only at the torpedo and cotyledonary embryo stages. Xylose was present at lower levels in all stages of embryogenesis than in the differentiated hypocotyl cell walls. These results suggest that there was a high turnover of arabinogalactan polysaccharides during embryogenesis, and that xylan accumulated in the cell walls of differentiated cells     

Dormancy break of celery (Apium graveolens L.) seeds by plant derived smoke extract

Seed dormancy of a highly-dormant cultivar of celery (Apium graveolens L.) was broken by combinations of plant-derived smoke extract or N⁶-benzyladenine (BA) and gibberellins A_4/7 (GA_4/7) in the dark at temperatures between 18 and 26°C. A less dormant cultivar which responded to GA_4/7 alone showed no additional response to smoke extract or BA. Neither smoke extract nor BA affected either cultivar in the dark in the absence of GA_4/7. The partial dormancy-breaking effect of short exposures to red-light was also enhanced by smoke extracts in this highly-dormant cultivar. The results suggest that smoke extracts act in a similar way to cytokinins, by enhancing gibberellin activity in the celery seed system.Abbreviations BA N⁶-benzyladenine - GA_4/7 A₄ and A₇ gibberellin mixture     

Germination of annual celery (Apium graveolens) seeds: Inhibition by paclobutrazol and its reversal by gibberellins and benzyladenine

Plants of annual celery ( Apium graveolens L.) were treated with paclobutrazol during anthesis. Seeds collected from the treated plants showed a marked reduction in germination in light and failed to germinate in the dark. Application of GA_4/7 to the imbibition solution reversed the inhibitory effect of paclobutrazol while gibberellic acid (GA₃) was ineffective. Benzyladenine (BA) interaction with GA_4/7 was light and concentration-dependent. At relatively low concentrations in the dark there was a synergistic effect, but at higher concentrations, especially in the light, BA, antagonized the GA_4/7 effect. Seedlings emerging from the seeds from paclobutrazol-treated plants were only slightly shortened. It is suggested that paclobutrazol applied to the mother plants inhibited the biosynthesis of endogenous GAs, which normally enable the germination of annual seeds under unfavorable conditions. Exogenously applied GA_4/7 fulfills the function of the absent endogenous GAs.     

A structural study of germination in celery (Apium graveolens L.) seed with emphasis on endosperm breakdown

Germination of celery seed occurred after 6 d of imbibition in light. During this time the embryo enlarged at the expense of the adjacent endosperm cells and at the time of germination was 2–3 times as long as in the dry seed. Breakdown of the endosperm cells near the root cap preceeded radicle emergence. None of these changes occurred in darkness.Endosperm digestion began adjacent to the embryo and spread radially. In degrading cells, the aleurone grains often became larger and fewer in number. The cell walls were modified and appeared to undergo partial degradation. Ultimately the cells seemed to lose their contents. In cells adjacent to the root cap, similar changes occurred except there was a transient appearance of starch grains. Radial progression of endosperm breakdown also occurred in isolated endosperm treated with gibberellin A₄₊₇.The results indicate that (1) the stimulus for breakdown of celery endosperm emanates from the embryo in response to light; (2) the stimulus may be a gibberellin because changes in endosperm cells and the sequence of endosperm digestion during germination resemble the responses of isolated endosperm to gibberellin; and (3) the radial progression of endosperm breakdown during germination may be the result of a sequential response of cells to a uniformly applied stimulus rather than the result of gradual embryo expansion.     

Cultivar differences in boron uptake and distribution in celery (Apium graveolens), tomato (Lycopersicon esculentum) and wheat (Triticum aestivum)

Species and cultivar differences in boron (B) uptake at low B availability and tolerance to high external B are known for many species but mechanisms explaining such differences remain obscure. Here we contrast B uptake and distribution between two cultivars of tomato and celery that differ significantly in their susceptibility to B deficiency. The celery cultivar S48-54-1 and tomato cultivar Brittle are known to be more susceptible to B deficiency (inefficient) than the closely related cultivars Emerson Pascal and Rutgers (efficient), respectively. B uptake and distribution was also compared in two wheat lines differing in tolerance to B excess (Chinese Spring, sensitive and Lophopyrum Amphiploid, tolerant). Results showed that there is no significant difference in either the specific uptake rate (I_M) of ¹⁰B or the relative growth rate (RGR) between the efficient cultivar (Emerson Pascal) and less efficient cultivar (S48-54-1) of celery. However, the distribution of ¹⁰B among plant organs (leaves, stems and roots) of Emerson Pascal was different from S48-54-1. In Emerson Pascal more than 63% of accumulated B was present in the shoots while in S48-54-1 only 45% of accumulated B was present in shoots. In tomato plants, in addition to differences in B distribution among plant organs between the efficient (Rutgers) and less efficient (Brittle) cultivars, the specific uptake rate of ¹⁰B was significantly higher in the efficient cultivar. In wheat, the tolerant line (Amphiploid) took up less B than the less tolerant cultivar (Chinese Spring), and the pattern of B distribution among plant organs was different with a greater percentage of B found in roots of Chinese Spring compared to Amphiploid. Differences in sensitivity to B deficiency and excess amongst cultivars and species were a consequence of either reduced B uptake as in wheat (Amphiploid), a restriction in B translocation from roots to shoot as in celery (S48-54-1) or a combination of both process as in tomato (Brittle).     

dbEST‐derived microsatellite markers in celery (Apium graveolens L. var. dulce)

We report on the development of 11 (from database expressed sequence tags) dbEST‐derived microsatellite markers in celery (Apium graveolens L. var. dulce). The sequences were obtained from DNA accessions available from GenBank and contained di‐, tri‐ and pentanucleotidic motifs. All the microsatellites were found in expressed sequence tags and they are expected to become useful tools for ecological, genetic and evolutionary studies, as well as for celery breeding. Polymorphism was explored in 16 celery commercial varieties, and marker transferability was tested on three accessions of celeriac (A. graveolens var. rapaceum). Primers and PCR conditions for microsatellite amplification are reported.     

The effect of sulfur-containing nitrogen fertilizers on the elemental composition of celery (Apium graveolens) grown on a polluted marsh soil

Summary In order to investigate elemental composition of celery, and to quantify the influence of sulfur-containing N-fertilizers on the trace element uptake, a field trial with celery was carried out on marsh soil polluted with municipal wastes. The research yielded the following results:Compared to leaves at harvest time, bulbs showed significantly lower concentrations of Mo, S and Sb, but higher contents of B, Br and Cr and Cu. Since the acidifying effect of the fertilizers was suppressed by the free calcium carbonate in the soil, no significant changes in concentrations of cationic trace elements were detected in plants fertilized with ammonium sulfate compared to those which received urea or calcium ammonium nitrate. On the other hand, in these plants the conspicuous increase in total sulfur was accompanied by a significant decrease in concentrations of up to 30% for B, Br and Sb, 50% for As, 60% for Se and 80% for Mo.According to these results, in plant production on contaminated soils certain plant parts may be marketable due to their low tendency to accumulate toxic elements, and furthermore it may be feasible to reduce the contents of some of these elements in plants by the use of sulfur-containing fertilizers.     

Comparative effects of gibberellins and an N-substituted phthalimide on seed germination and extension growth of celery (Apium graveolens L.)

The N-substituted phthalimide AC 94377 (1-(3-chlorophthalimido)-cyclohexanecarboxamide) was equally effective as a mixture of the gibberellins A₄ and A₇ (GA_4/7) in breaking dormancy and stimulating germination of celery seeds when either was used in combination with ethephon or daminozide as a seed soak. Whereas seedlings emerging from GA_4/7-treated seeds became etiolated in comparison with those from untreated seeds, those from AC 94377-treated seeds showed normal development. Preharvest sprays of gibberellic acid (GA₃) increased the height of mature plants in comparison with untreated controls by about 16 per cent whereas AC 94377 was ineffective. The yield from GA₃-treated plots was about 10 per cent greater than that from AC 94377-treated plots.     

Electrofusion of protoplasts from celery (Apium graveolens L.) with protoplasts from the filamentous fungus Aspergillus nidulans

A method was developed for electrofusion of higher-plant protoplasts from celery and protoplasts from the filamentous fungus Aspergillus nidulans. Initially, methods for the fusion of protoplasts from ecch species were determined individually and, subsequently, electrical parameters for fusion between the species were determined. Pronase-E treatment and the presence of calcium ions markedly increased celery protoplast stability under the electrical conditions required and increased fusion frequency with A. nidulans protoplasts. A reduction in protoplast viability was observed after electrofusion but the majority of the protoplasts remained viable over a 24-h incubation period. A small decline in protoplast respiration rate occurred during incubation but those celery protoplasts fused with A. nidulans protoplasts showed elevated respiration rates for 3 h after electrofusion.Abbreviations AC alternating current - DC direct current