The Emergence and Early Growth of the Lateral Root in Vicia faba L.

The duration of the mitotic cycle, as well as the proportionof cells with long and short cycle times and quiescent cells,have been investigated in the apical meristems of young lateralroots of Vicia faba. No changes took place in the duration ofC or in the phases of the mitotic cycle as the lateral rootemerged from the primary root, though the proportion of proliferatingcells increased and the quiescent fraction of cells decreased.It is suggested that the low frequency with which newly emergedlateral roots label with ³H-TdR is a result of the formationof a large endogenous pool of TdR in the meristems during theperiod they are temporarily quiescent. The changes which tookplace in the parameters of cell proliferation during the earlygrowth of the lateral root have been correlated with those inroot apical meristems following the onset of seed germination.     

Tritiated-thymidine Labelled Nuclei in Primordia and Newly-emerged Lateral Roots of Vicia faba L.

The utilization of ³H-TdR in DNA synthesis and the distributionof labelled nuclei have been determined in large primordia (LP)and newly emerged lateral roots (JE) of Vicia faba followingdifferent exposure periods. This nucleoside appears to reachLP and the more basal, unemerged parts of JE by way of the vasculartissue of the primary root, while those parts of JE which projectout from the epidermis of the primary obtain ³H-TdR directlyfrom the surrounding medium. The utilization of ³H-TdR in thesynthesis of DNA in basal segments of JE is also complicatedby the temporary quiescence of nuclei in this part of thesemeristems as LP elongate to form lateral roots.     

The Distribution of Nitrate Assimilation Between Root and Shoot in Vicia faba L.

Nitrate assimilation was examined in two cultivars (Banner Winterand Herz Freya) of Vicia faba L. supplied with a range of nitrateconcentrations. The distribution between root and shoot wasassessed. The cultivars showed responses to increased applied nitrateconcentration. Total plant dry weight and carbon content remainedconstant while shoot: root dry weight ratio, total plant nitrogen,total plant leaf area and specific leaf area (SLA) all increased.The proportion of total plant nitrate and nitrate reductase(NR) activity found in the shoot of both cultivars increasedwith applied nitrate concentrations as did NO₃^–: Kjeldahl-Nratios of xylem sap. The cultivars differed in that a greaterproportion of total plant NR activity occurred in the shootof cv. Herz Freya at all applied nitrate concentrations, andits xylem sap NO₃^–: Kjeldahl-N ratio and SLA were consistentlygreater. It is concluded that the distribution of nitrate assimilationbetween root and shoot of V. faba varies both with cultivarand with external nitrate concentration. Vicia faba L., field bean, nitrate assimilation, nitrate reductase, xylem sap analysis     

Some properties of the amine oxidase in Vicia faba seedlings

Growth of the Vicia faba seedling is accompanied by a rapid15-day increase in amine oxidase activity of the apical parts.Cotyledons and roots were found to be devoid of activity. Thepartially purified enzyme from leaves readily oxidized putrescine,cadaverine, agmatine and spermidine, while dopamine (3-hydroxytyramine)and L- and D-lysine were oxidized more slowly. The Km valueswere 1.9?10^–3 M for cadaverine, 3.7?10^–5 M for putrescine,7.8?10^–4 M for spermidine, and 5.9?10^–3 M for dopamine.Carbonyl reagents and copper-binding agents were effective inhibitorsof Vicia faba amine oxidase. The diethyldithiocarbamate-treatedenzyme could be reactivated specifically by cupric copper. (Received May 25, 1977; )     

Lateral Root Anlage Development in Excised Roots of Vicia faba L., Pisum sativum L., Zea mays L. and Phaseolus vulgaris L.

The development of lateral root primordia has been investigatedin excised roots of Vicia faba, Pisum sativum, Zea mays andPhaseolus vulgaris cultured in White's medium supplemented with2 per cent sucrose and compared with previously published dataon such development in primaries of the corresponding intactplants (control roots). Primordia were produced in each batchof excised roots over the 6 day culture period but at a lowerrate (number day^–1) than in the controls. Such primordia in cultured roots of Zea and Phaseolus completedtheir development and grew out as lateral roots over a periodsimilar in length to that found in the controls, but with acell number of only about 33 per cent of that attained at thetime of secondary emergence in the primaries of the latter roots.These lower cell numbers were at least partly a reflection ofincreases in mean cell doubling time over the period of anlagedevelopment investigated in the excised roots relative to thecorresponding values found in the controls. Primordia initiated in excised roots of Pisum and Vicia didnot complete their development in culture, i.e. no lateral rootsemerged and arrest took place with cell numbers of only 37 (Pisum)and 17 (Vicia) per cent of the numbers determined at the timeof secondary root emergence in the controls. Such arrested primordiahad few nuclei in S and none in mitosis. Moreover, at leastin Pisum, the frequency distribution of the relative DNA contentof the nuclei in the latter primordia approximated that foundin the apical meristem of primary roots following the establishmentof the stationary phase under conditions of carbohydrate starvation. It has also been demonstrated in the course of these investigationsthat lateral root primordium development in all four speciesis at least biphasic and possibly triphasic. Vicia faba L., broad bean, Pisum sativum L., garden pea, Zea mays L., maize, Phaseolus vulgaris L., dwarf bean, root primordia, anlage, cell doubling time, lateral root emergence     

Thymidine Kinase Activity and its Relationship to DNA Synthesis in the Primary Root of Vicia faba, L.

The enzyme thymidine kinase can be induced, or activated, inthe apical 6 cm of the primary root of Vicia faba. The activityof this enzyme is correlated with the amount of thymidine triphosphatepresent in successive 6-mm segments of the root. Thymidine isproduced by cell death. Some of this thymidine may reach themeristem and be used by the apical cells in DNA synthesis, onceit is phosphorylated by thymidine kinase. Most remains in thebasal region of the root, however, where it is used by differentiatingcells. Non-radioactive thymidine, at the concentrations used,has no effect on root growth by elongation.     

Total Uptake and Incorporation into DNA of 3H-Thymidine, 3H-Deoxyuridine, and 3H-Thymine in the Primary Root of Vicia faba L.: II. EXCISED ROOTS

Total uptake of ³H-thymidine, ³H-thymine, and ³H-deoxyuridineand incorporation of these substances into DNA have been investigatedin excised roots in Vicia faba. Total uptake was found to behigher in excised roots than in intact ones. This was a consequenceof exogenous ³H-DNA precursors entering the excised roots throughthe cut surface. Where the cut surface was not immersed in the³H-thymidine solution ³H uptake was also higher than in intactroots. In this case ³H uptake scemed to be correlated with water-lossfrom the cut surface. Incorporation of ³H-thymidine, ³H-thymine,and ³H-deoxyuridine into DNA was found to be higher in excisedroots than in intact ones, probably as a result of a decreasein the size of the relevant endogenous precursor pools. It issuggested that this decrease resulted from the cessation ofthe supply of DNA precursors to these roots from the cotyledons.     

Para-nitrophenyl Phosphate as a Substrate for Some Acid Phosphatases in Roots of Vicia faba

A cytochemical and biochemical study of acid phosphatases inroots of Vicia faba using p-nitrophenylphosphate(p-NPP) as substratehas shown the lack of specificity of the substrate which canbe acted upon by a K⁺-activated acyl phosphatase, nucleotidepyrophosphatase, glucox-6-phosphatase, 5' (3')-ribonucleotidephosphohydrolase, nucleotide phosph-transferase and those acidphosphatases demonstrable with ß-glycerophosphate.It is suggested that care should be taken in the interpretationof both biochemical and cytochemical studies employing sucha non-specific substrate as P-NPP. Vicia faba, broad bean, root, acid phosphatases     

Tissue 3Vicia Faba

The establishment of a callus culture of Vicia faba root tissuegrowing on a modified Bonner and Devirian medium supplementedwith 10^-6 M 2,4-dichlorophenoxyacetic acid and 5.0 g/l yeastextract is reported. Experiments have been carried out to determinethe optimum growth conditions of the callus on semisolid mediaand an investigation made of the potential of this materialas an initial source of friable tissue yielding cell suspensionson dissociation in liquid medium. The development of two morphologicallydistinct types of callus tissue was observed on semi-solid mediumand chemical analysis has demonstrated a correlation betweenthe friability and cell-wall composition of these tissues.     

Distribution of Radioactivity from Exogenously Supplied [1-14C]Indol-3-yl-acetic Acid and [3, 4-3H (N)] Gibberellin A, in Geotropically-stimulated Picea abies (L.) Karst. Roots

The distribution of exogenously-supplied radioactive labelledindol-3-yl-acetic acid (IAA) and gibberellin A₁ (GA₁) in geotropicallystimulated roots of Norway spruce (Picea abies (L.) Karst.)has been demonstrated. Seedlings were positioned with theirroot tips in 2.1 x 10^–6 M [¹⁴C]IAA or 1.3 x 10^–8m ³H-GA₁ for 4 and 20 h, respectively. After geotropic stimulationfor 90 min in the horizontal position the root tips were cutlongitudinally in 50 µm thick sections, using a freeze-microtome.The radioactivity in the ¹⁴C-IAA treated roots occurred in higherconcentration in the lower than in the upper halves (ratio 1.25:1). A similar trend was observed in the [³H]GA₁-treated rootswhere the ratio lower: upper halves was 2.04: 1. The ratio ofradioactivity in right and left halves of vertical roots wasapproximately the same in roots supplied with [¹⁴C]IAA and [³H]GA₁(1.09: 1). The supplied radioactive compounds were analysed chromatographicallyafter extraction in methanol of 6 mm apical root segments. Onlya small fraction (7–8 per cent) of the supplied [¹⁴C]IAAwas revealed unchanged in the segments. The major part of thechromatographed, labelled compound has not been identified,but on basis of its R_F value it is suggested that it may beindol-3-acetyl-aspartic acid (IAAasp). The chromatographic analysis of the [³H]GA,-treated segmentsshowed that only small fractions of this gibberellin has beenconverted to other compounds. These results have been discussed and correlated with knowledgeof plant growth regulators and their participation in root geotropism. Picea abies, spruce, geotropism, gibberellin A₁, indol-3-yl-acetic acid, growth regulators, redistribution in roots     

The Effect of Different Levels of N Limitation on Sugars, Amino Acids, Growth and Biomass Partitioning in Broadbean (Vicia faba L.)

Broadbean plants (Vicia faba L.) were submitted to three differentlevels of steady state N limitation. Relative addition ratesof N were 0.06, 0.1 and 0.14d^-1. Plants were harvested at fiveevenly distributed times over a 2d period. Shoot growth correspondedwell with the imposed treatment. Root growth, relative to shootgrowth, was highest at the 0.06d^-1treatment. Diurnal patternsof soluble sugars, amino acids and starch were analysed. Onaverage, soluble sugar levels were highest in the plants ofthe 0.06d^-1treatment whereas average free amino acid levelswere highest in the 0.14d^-1treatment. Shoot growth increasedas the concentration of shoot amino acids increased. No suchcorrelation however could be found between root growth and freesugar levels in the root. Broadbean; Vicia faba L.; exponential addition; N limitation; free sugar; amino acids; diurnal cycle; functional equilibrium; starch     

Transport of shoot- and cotyledon-applied indole-3-acetic acid to Vicia faba root

To clarify the participation of indole-3-acetic acid (IAA) originatingfrom the shoot in root growth regulation and the mechanism ofIAA translocation from shoot to root, the movement of ¹⁴C-IAAwhich was applied to the epicotyl or the cotyledon of Viciafaba seedlings was investigated. The radioactivity of IAA appliedto the cotyledon moved faster to the root tip than that appliedto the epicotyl. On the basis of the effect of 2,3,5-triiodobenzoic acid on IAAmovement, a comparison with ¹⁴C-glucose movement and autoradiographicexamination, the nature of IAA movement was concluded to bepolar transport from the epicotyl to the basal part of the roots,while IAA movement from the epicotyl to the cotyledon, fromthe basal part of roots to the apical part, and from the cotyledonto the epicotyl and to the root took place in the phloem. Theradioactivity from ¹⁴C-IAA applied to the cotyledon accumulatedin lateral root primordia and vascular bundles. These factssuggest that IAA produced in cotyledons may participate in theregulation of Vicia root development. (Received December 21, 1979; )     

Effects of NaCl on Growth, Nitrogen Incorporation and Chemical Composition of Inoculated and NH4NO3 Fertilized Vicia faba (L. ) Plants

Vicia faba cv. Maris Bead was grown either on fixed nitrogenor on ammonium nitrate. After 4 weeks growth, nutrient solutionswere supplemented with 50, 75 and 100 mol m^–3 NaCl for15 d. Five harvests were made at weekly intervals, beginningat 4 weeks. Effects of salinity were directly related to dose,plant growth (fresh and dry weight) being depressed in bothN-fixing and N-fertilized plants. The number of nodules perplant and the proportion of those formed which developed intothe active nitrogen fixing state were depressed by salt stress.Increased size of nodules in salt-stressed plants only partlycompensated for the lower specific nitrogenase activity. Theeffects of salinity on plant nitrogen content were more pronouncedon N-flxing than on N-fertilized plants. The former took upmore Na⁺ and Cl^– than the latter: the implications ofthis and of ionic imbalance are discussed. Key words: Vicia faba, Growth, Salt stress, Nodulation     

Carbon and Nitrogen Assimilation by Vicia faba L. at Low Temperature: the Importance of Concentration and Form of Applied-N

Low temperature (6 C) growth was examined in two cultivarsof Vicia faba L. supplied with 4 and 20 mol m^–3 N as nitrateor urea. Both cultivars showed similar growth responses to increasedapplied-N concentration regardless of N-form. Total leaf areaincreased, as did root, stem and leaf dry weight, total carboncontent and total nitrogen content. In contrast to findingsat higher growth temperatures, 20 mol m^–3 urea-N gavesubstantially greater growth (all parameters measured) than20 mol m^–3 nitrate-N. The increased carbon content per plant associated with increasedapplied nitrate or urea concentration, or with urea in comparisonto nitrate, was due to a greater leaf area per plant for CO₂uptake and not an increased CO₂, uptake per unit area, carbon,chlorophyll or dry weight, all of which either remained constantor decreased. Nitrate reductase activity was substantial inplants given nitrate but negligible in plants given urea. Neitherfree nitrate nor free urea contributed greatly to nitrogen levelsin plant tissues. It is concluded that there is no evidence for a restrictionin nitrate reduction at 6 C, and it is likely that urea givesgreater growth than nitrate because of greater rates of uptake. Vicia faba, broad bean, low temperature growth, carbon assimilation, nitrogen assimilation     

Chromosome Aberrations and Ageing Root Meristems

Changes in mitotic activity and frequency of spontaneous chromosomeaberrations have been determined for primary roots of Zea muys,Pisum sativum, Vicia faba var. green Windsor and var. minor,and Allium cepa. Mitotic activity was found to decline withage in all root apices. In the primary root apices immediately after germination, therewas a high frequency of spontaneous chromosome aberrations whichdeclined with time after germination. However, In the case ofV. faba var. green Windsor, Z mays and P. sativum there wasa return to the high levels of spontaneous chromosome aberrationon ageing of the root apex. root meristems, mitotic activity, chromosome aberrations, ageing     

Mechanism of Photosynthate Efflux from Vicia faba L. Seed Coats

In order to develop a tentative model of the mechanism of photosynthateefflux from the vascular region of Vicia faba L. seed coats,wash-out experiments were performed after removal of the embryo. The sulphydryl group modifiers, pCMBS and NEM, reduced ¹⁴C-photosynthateefflux by 40% and 50%, respectively. Their inhibitory effectcould be prevented or reduced (in the latter case) by includingDTT in the bathing solution. Maltose competed with sucrose forefflux; a concentration of 300 mol m^–3 inhibited ₁₄C-photosynthaterelease by 35%. The cations K⁺ , Na⁺ Mg²⁺ and TPP⁺ enhancedefflux significantly, whereas the countenon Cl^– had noeffect. The presence of the protonophore CCCP (0·1 molm^–3) led to a reduction of efflux by 50% net proton extrusiondropped by 34%. To a lesser extent, an efflux inhibition wasalso achieved by decreasing the cytoplasmic pH with the weakacid DM0. In contrast, alterations in the external pH causedonly a feeble response. The ATPase inhibitor, EB, decreasedphotosynthate efflux and H⁺ extrusion. DES reduced efflux slightly,presumably by affecting ATPase activity as well as energy metabolism. Based on these findings, it is proposed that a sucrose/protonantiport mechanism could be responsible for photosynthate effluxfrom Vicia faba seed coats. Key words: Photosynthate efflux, proton extrusion, proton/sucrose antiport, seed coat, Vicia faba L.     

In Vitro Culture and Plant Regeneration in Vicia faba subsp. Equina (var. Spring Blaze)

Explants of stem, leaves, roots, and cotyledons from etiolatedaxenically grown Vicia faba seedlings were cultured on a rangeof media. Shoot organogenesis was only obtained with nodal stemand cotyledonary node explants when cultured on MS medium with3% sucrose, 2.0 mg 1^–1 BAP and 02 mg 1^–1 NAA. Callusproliferation accompanied shoot organogenesis from nodal stemexplants. Successive subculture of nodal stem callus resultedin proliferation of regenerative callus which contained severalshoot bud initials. The capacity for shoot regeneration fromthis callus was maintained for 9 months. Histological studiesreveal de novo formation of meristematic centres in callus andtheir further development into bud primordia. High frequencyrooting of these adventitious shoots was obtained on half-strengthMS medium with 1.5% sucrose, 0.1 mg 1^–1 NAA and 0.5 mg1^–1 kinetin. Key words: Vicia faba, adventitious shoots, axillary shoots, de novomeristem formation, organogenesis, tissue culture     

Some Observations on Invertase Activity in Roots of Vicia faba L.

Invertase activity has been determined at intervals along primaryroots of Vicia faba as they elongated from 0·5 to 8 cm.Little activity was evident in 0·5–1·0 cmlong primaries but in those 2–8 cm in length the mainpeak of enzyme activity was associated with the region of cellelongation. Changes took place in the pattern of invertase activityalong the primary roots as they lengthened and these changeshave been correlated with fluctuations in both the rate of rootelongation and the supply of sucrose to the root from the cotyledons.The presence of a root cap did not increase the activity ofthis enzyme in the apical 1 mm of these roots. Invertase activity was higher in lateral root primordia thanin most parts of the primary root basal to the meristem, presumablybecause of the presence of sucrose in the adjacent cavity inthe cortex of the primary root. The peaks of invertase activityfound basal to the region of cell elongation in 3–8 cmlong primary roots probably resulted from the development ofroot pnmordia in these parts of the root.     

Changes in the Chromosome Complements of Cells of Vicia faba Roots following Irradiation

1. Primary roots of Vicia faba were irradiate after one day'sgermination. The X-ray dose was 620 r 2. Cells with changed chromosome complements appeared in lateralroots. It is inferred that these cells are descended from cellsdamaged by irradiation; chromosome breakage was seen in thefirst mitoses in the irradiated roots but was not scored. 3. Six types of chromosomal rearrangements were found. One typehad been reported previously in primary roots of V. faba afterX-raying. 4. The new complements appear to be stable because they occurseveral cells of a lateral. Affected laterals could containup to five new complements. The primordium of such a lateralmust have consisted of five changed and at least one normalcell. It had previously been suggested that a root of Viciahad three or four initial cells. 5. The survival of the cells with changed complements is notdue solely to successful competition with, not to support by,normal cells, otherwise other types of changes should also havebeen found. 6. It is suggest that the changes found were perpetuated becausethey were induced in initial cells of the primary root, andthat cells in which they were present beca,e part of the primordialand continued as initial cells in apical meristems of lateralroots. 7. Apical cells appear to have a lower sensitivity than othermeristematic cells, so providing, after treatment, a reservoirof normal cells from which regeneration can occur.     

Inhibitory effect of fusicoccin on cell division

Rapid interactions in cell division and cytodifferentiationare induced by hormone treatments in dark-cultured explantsof Jerusalem artichoke. Fusicoccin, at concentrations between10^–6 and 10^–5 M, markedly inhibited the division-promotingactivity induced by plant hormones. Further, fusicoccin-treatedmeristematic root tips of Vicia faba and Allium cepa showeda rapid decrease in the mitotic index. Fusicoccin seems to inhibitsome hormone-sensitive processes required during the inductionand regulation of cell division. (Received March 28, 1979; )