Observations on the reduction of non-activated carboxylates by Clostridium formicoaceticum with carbon monoxide or formate and the influence of various viologens

Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E ₀=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.Non-standard abbreviations glc Gas liquid chromatography - HPLC high performance liquid chromatography - RP reverse phase; Mediators (the figures in parenthesis of the mediators are redox potentials E ₀ in mV) - CAV²⁺ carbamoylmethylviologen, 1,1-carbamoyl-4,4-dipyridinium dication (E ₀=-296 mV) - BV²⁺ benzylviologen, 1,1-dibenzyl-4,4-dipyridinium dication (E ₀=-360 mV) - MV methylviologen, 1,1-dimethyl-4,4-dipyridinium-dication (E ₀=-444 mV) - DMDQ²⁺ dimethyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-ethylendication (E ₀=-514 mV) - TMV²⁺ tetramethylviologen, 1,1,4,4-tetramethyl-4,4-dipyridinium dication (E ₀=-550 mV) - PDQ²⁺ propyldiquat, 2,2-dipyridino-1,1-propenyl dication (E ₀=-550 mV) - DMPDQ²⁺ dimethylpropyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-propenyl dication (E ₀=-656 mV) - PN productivity number=mmol product (obtained by the uptake of one pair of electrons) x (biocatalyst (dry weight) kg)^-1×h^-1     

Nicotianamine and the distribution of iron into the apoplasm and symplasm of tomato (Lycopersicon esculentum Mill.)

The apoplasmic and symplasmic iron pools were determined in roots and leaves of Lycopersicon esculentum Mill. cv. Bonner Beste and its mutant chloronerva. The mutant is auxotrophic for the ubiquitous plant constituent nicotianamine (NA) and exhibits an impaired iron metabolism. Formation of apoplasmic iron pools in roots was dependent on the iron source in the nutrient solution. With Fe-ethylenediaminedi-(2-hydroxyphenylacetate) (FeEDDHA) only a very small apoplasmic iron pool was formed in the roots of both genotypes. Plants grown with FeEDTA increased their apoplasmic iron pool with increasing exogenous iron concentrations in the nutrient solution. The size of the apoplasmic pools in roots did not differ between the wild-type and the mutant (about 85 mol Fe · g^–1 DW). By contrast, the symplasmic iron concentrations in roots and leaves of the mutant were significantly higher when compared to the wild-type. An exogenous NA supply to the leaves of the mutant reduced the high symplasmic iron concentrations to the level of the wild-type. Mutant leaves exhibited a gradient of symplasmic iron concentrations depending on the developmental age of the leaves. The oldest leaves contained considerably more symplasmic iron than the youngest. The results demonstrate that the apparent iron deficiency of the mutant is not the consequence of an impaired iron transport from the apoplasm to the symplasm. Therefore, it is concluded that NA is not required for the transport of Fe(II) through the plasmalemma into the cell.Abbreviations BPDS bathophenanthroline disulfonic acid, Na₂ salt - FeEDDHA ferric N-N-ethylenediaminedi-(2-hydroxy-phenylacetate) - NA nicotianamine Part 40 in the series The normalizing factor for the tomato mutant chloronerva. For part 39 see Pich et al. (1991)The valuable technical assistance of Mrs. Christa Kallas and Mr. Günter Faupel is gratefully acknowledged.     

A genetically related response to iron deficiency stress in muskmelon

A mutant muskmelon (Cucumis melo L.) with characteristic Fe-deficiency chlorosis symptoms was compared to related cultivars in its ability to obtain Fe via the widely known Fe-stress response mechanisms of dicotyledonous plants. The three cultivars (fefe, the Fe-inefficient mutant; Mainstream and Edisto, both Fe efficient plants) were grown in nutrient solution in either 0 or 3.5 mg L^-1 Fe as FeCl₃. None of the three cultivars released reductants or phytosiderophores, but both Edisto and Mainstream produced massive amounts of H+ ions to reduce and maintain the pH of nutrient solutions below pH 4.0. The roots of these two Fe-efficient cultivars were also capable of reducing Fe³⁺ to Fe²⁺. These responses maintained green plants, resulted in high leaf Fe in both Edisto and Mainstream, and produced Mn toxicity in Mainstream. The lack of Fe-deficiency stress response in fefe not only affected leaf Fe concentration and chlorosis, but also resulted in reduced uptake of Mn. The importance of reduced Fe (Fe²⁺) to the Fe-efficient cultivars was confirmed by growing the cultivars with BPDS (4, 7-diphenyl-1, 10-phenanthroline disulfonic acid, a ferrous chelator) and EDDHA [ethylene-diamine di (0-hydroxphenylacetic acid)] (a ferric chelator), and observing increased chlorosis and reduced Fe uptake in BPDS grown plants. The Fe-deficiency response observed in these cultivars points out the diversity of responses to Fe deficiency stress in plants. The fefe mutant has a limited ability to absorb Fe and Mn and perhaps could be used to better understand Mn uptake in plants.     

Calculation of leaf photosynthetic parameters from light-response curves for ecophysiological applications

Measurement of the light response of photosynthetic CO₂ uptake is often used as an implement in ecophysiological studies. A method is described to calculate photosynthetic parameters, such as the maximum rate of whole electron transport and dissimilative respiration in the light, from the light response of CO₂ uptake. Examples of the light-response curves of flag leaves and ears of wheat (Triticum aestivum cv. ARKAS) are shown.Abbreviations and symbols A net photosynthesis rate - D ¹ rate of dissimilative respiration occurring in the light - f loss factor - I incident PPFD - I effective absorbed PPFD - J rate of whole electron transport - J _m maximum rate of whole electron transport - p ^c intercellular CO₂ partial pressure - PPFD photosynthetic photon flux density - q effectivity factor for the use of light (electrons/quanta) - absorption coefficient - I ^* CO₂ compensation point in the absence of dissimilative respiration (bar) - II conversion factor for calculation of CO₂ uptake from the rate of whole electron transport - convexity factor Gas-exchange rates relate to the projective area and are given in mol·m^-2·s^-1. Electron-transport rates are given in mol electrons·m^-2·s^-1; PPFD is given in mol quanta·m^-2·s^-1.     

The effect of leaf source and developmental stage on shoot organogenic potential of sweetgum (Liquidambar styraciflua L.) leaf explants

Leaf explants harvested from shoot proliferating cultures and intact plants of Liquidambar styraciflua Variegata were placed on solidified Woody Plant medium supplemented with 0.1 mgl^-1 (0.5 M) naphthaleneacetic acid and 2.5 mgl^-1 (11.1 M) benzyladenine to initiate shoot meristems directly. Leaves from intact plants produced over 4 times more adventitious shoots than leaves from in vitro shoots and had a greater tendency to form shoots on the lamina. The relative developmental age of leaf tissue used dramatically influenced the shoot organogenic response observed for leaf explants from intact plants of L. styraciflua Variegata and Moraine.-Leaves that were either 20% or 50% of full size and still actively expanding were superior to other developmental stages for shoot organogenesis. As developmental leaf age increased throughout the period of leaf expansion, the number of shoots forming on the petiole stub remained constant, whereas shoot formation on the lamina increased 8 fold. Shoots derived from Variegata leaves rooted well and grew normally as plants. Differences in rooting ability and plant size could be detected between groups that had been separated according to explant source (in vitro vs. intact plant) and the location of shoot formation (petiole vs. lamina).     

Below-ground biomass in healthy and impaired salt marshes

Twelve salt marshes in south Louisiana (USA) were classified as either impaired or healthy before a summer sample collection of above- and below-ground biomass and determination of sediment accretion rates. The above-ground biomass of plant tissues was the same at both impaired and healthy salt marshes and was not a good predictor of marsh health. However, below-ground root biomass in the upper 30cm was much lower in the impaired marshes compared to the healthy marshes. Compromises to root production apparently occur before there is an obvious consequence to the above-ground biomass, which may quickly collapse before remedial action can be taken. The subsequent change in vertical position of the marsh surface may be equivalent to many years of accretion, and be irreversible within decades without considerable effort. These results are consistent with the hypothesis that it is the plants below-ground accumulation of organic matter, not inorganic matter that governs the maintenance of salt marsh ecosystem in the vertical plane. Reversing the precursor conditions leading to marsh stress before the collapse of the above-ground biomass occurs is therefore a prudent management objective and could be easier than restoration.     

Influence of the nitrogen level on root growth and morphology of two potato varieties differing in nitrogen acquisition

Two potato (Solanum tuberosum L.) cultivars (Astrid and Bodenkraft) differing in their nitrogen acquisition from the soil (Hunnius, 1981) were used in nutrient solutions to study the effect of increasing concentrations of nitrate (0.05; 0.5; 5.0 mol m^-3) particularly on root growth and morphology. In each variety increasing nitrogen concentrations stimulated shoot growth more than root growth. At all nitrate concentrations, the variety with higher nitrogen acquisition (Astrid) had a significantly larger root system. The larger root system of Astrid compared to Bodenkraft was particularly evident when surface area and total length of the roots, instead of root dry weight were used as parameters. The results stress the importance of root length and surface area for nitrogen acquisition from soils.     

In vitro plant regeneration from leaves and internode sections of sweet cherry cultivars (Prunus avium L.)

Regeneration of adventitious shoots from leaves and, for the first time, from internode sections were compared and optimized for five economically important sweet cherry cultivars, i.e. Schneiders, Sweetheart, Starking Hardy Giant, Kordia and Regina (Prunus avium L.). The influence of basal media, carbon source, combination and dosage of phytohormones, ethylene inhibitor such as silver thiosulfate and a 16 h:8 h light:dark photoperiod versus complete darkness were evaluated. Both, DKW/WPM (1:1) and Quoirin/Lepoivre (QL) basal media stimulated organogenesis more than QL/WPM (1:1), Chee and Pool (CP), Murashige Skoog (MS), Driver and Kuniyuki (DKW) or woody plant (WPM) media did. An induction phase in darkness resulted in lower or zero regeneration rates. The best regeneration efficiencies were generally obtained with thidiazuron in combination with indole-3-butyric-acid. The addition of silver thiosulfate resulted in a similar or reduced regeneration efficiency. Significant genotypic variability in adventitious bud formation was evident for both explant sources, leaf and internode section. Adventitious shoots were obtained from 11% of leaf explants and 50% of internode sections indicating that shoot regeneration from internodes was significantly more efficient than from leaves.     

Influence of varied zinc supply on re-translocation of cadmium (109Cd) and rubidium (86Rb) applied on mature leaf of durum wheat seedlings

Effect of varied zinc (Zn) supply (0, 0.1, 1, 5 M) on re-translocation of radio-labeled cadmium (¹⁰⁹Cd) and rubidium (⁸⁶Rb) from mature leaf to root and other parts of shoot was studied in 11-day-old durum wheat (Triticum durum cv. C-1252) plants grown in nutrient solution under controlled environmental conditions. Application of ¹⁰⁹Cd and ⁸⁶Rb was carried out by immersing the tips (3 cm) of mature leaf in radio-labeled solutions for 10 s at three different times over a 42 h period. Differences in Zn supply for 11 days did not affect plant growth nor did it cause visual leaf symptoms, such as necrosis and chlorosis, at either the lowest or the highest Zn supply. Only at the nil Zn supply (0 M), shoot and root dry weights tended to decrease and increase, respectively, causing a lower shoot/root dry weight ratio. Partitioning of more dry matter to roots rather than shoots, a typical phenomena for Zn-deficient plants in nutrient solution experiments, indicated existence of a mild Zn deficiency stress at the nil-Zn treatment. Irrespective of Zn supply, plants could, on average, retranslocate 3.8% and 38% of the total absorbed ¹⁰⁹Cd and ⁸⁶Rb from the treated leaf to roots and other parts of shoots within 42 h, respectively. At nil-Zn treatment, 2.8% of the total absorbed ¹⁰⁹Cd was re-translocated from the treated leaf, particularly into roots. The highest re-translocation of ¹⁰⁹Cd (6.5%) was found in plants supplied with 0.1 M Zn. Increases in Zn supply from 0.1 M reduced ¹⁰⁹Cd re-translocation from 6.5% to 4.3% at 1 M Zn and 1.3% at 5 M Zn. With the exception of the nil-Zn treatment, the proportion of re-translocated ¹⁰⁹Cd was greater in the remainder of the shoot than in the roots. Contrary to the ¹⁰⁹Cd results, re-translocation of ⁸⁶Rb was not (at 0, 0.1 and 1 M Zn), or only slightly (at 5 M), affected by changing Zn supply. The results indicate an inhibitory action of increased concentrations of Zn in shoot tissues on phloem-mediated Cd transport. This effect is discussed in relation to competitive inhibition of Cd loading into phloem sap by Zn.     

Effect of excess boron on summer and winter squash

The boron tolerance of two summer squash cultivars (Cucurbita pepo L. Aristocrat Zucchini and Peter Pan Scallop) and one winter squash cultivar (Cucurbita moschata Poir. Butter boy) was determined in large, outdoor sand cultures. Boron treatments were imposed by irrigation with culture solutions that contained 1.0, 3.0, 6.0, 9.0, 12.0, or 15.0 mg B L^-1. Relative fruit yields of Zucchini, Scallop, and Butter boy were reduced 5.2%, 9.8%, and 4.3% with each unit (mg L^-1) increase in soil solution B (B_sw)>2.7, 4.9, and 1.0 mg B L^-1, respectively. Reduced yields of all cultivars were attributed to a reduction in fruit number and not fruit size. Boron concentrations in leaves and fruit were directly correlated to B_sw.     

Characterization of solute/proton cotransport in plasma membrane vesicles from Ricinus cotyledons,and a comparison with other tissues

Plasma membrane vesicles, purified by aqueous two-phase partitioning, were used to investigate the presence of sugar and amino acid carriers in cotyledons and roots of Ricinus communis L. and in roots of red beet (Beta vulgaris L.). Artificial pH and electrical gradients were generated across the plasma membrane, and [¹⁴C]acetate and [¹⁴C]tetraphenylphosphonium were used to demonstrate the presence of an internal alkaline pH gradient and an internal negative membrane potential, respectively. In Ricinus cotyledons, uptake of sucrose was more strongly inhibited than that of glutamine by p-chloromercuribenzenesulphonic acid, phlorizin and phenylglyoxal. The sucrose transport system showed a high degree of substrate specificity with only the presence of maltose and phenyl--glucoside significantly affecting sucrose uptake; in contrast, the glutamine transport system was inhibited by a number of other amino acids. pH+gD-driven glutamine uptake showed saturation kinetics with a K _m of 0.35 mol · m^–3. Sucrose and glutamine -driven uptake was pH dependent with an optimum in the acidic range (pH 6.25) and a decrease at higher pH values. Vesicles obtained from cotyledons and roots of Ricinus showed different transport properties. In the cotyledons, gDH+gD-driven transport for both sucrose and glutamine were observed at similar levels; however, in the root tissue, pH--driven glutamine transport was the dominant uptake process. Uptake rates for glucose and fructose were low in the cotyledons whereas, in the roots, glucose and sucrose transport were slightly higher than that of fructose. In vesicles from red beet tissue there was a different uptake profile, with evidence of proton-coupled cotransport systems for sucrose and glucose, but lower uptake of glutamine and fructose. The results are discussed in relation to the reported different pathways for loading and unloading of solutes in these tissues.Abbreviations CCCP carbonyl cyanide-m-chlorophyenyl hydrazone - DEPC diethyl pyrocarbonate - NEM N-ethylmaleimide - PCMBS p-chloromercuribenzenesulfonic acid - TPP tetraphenylphosphonium ion - gDH⁺ proton electrochemical potential gradient - membrane potential We would like to thank the SERC(UK) and the Royal Society for financial support.     

Plant regeneration and genetic transformation of Lotus angustissimus

Culture conditions have been established for callus induction and growth from different explants in L. angustissimus L. Calli were obtained from hypocotyls, leaves, stems, cotyledons and roots cultured on media containing 2,4-dichlorophenoxyacetic acid or -naphthaleneacetic acid with kinetin, N⁶ – ² or benzyladenine in different combinations and concentrations. Only those calli induced in presence of -naphthaleneacetic acid with benzyladenine or kinetin produced shoots. Calli induced from hypocotyl explants were the most efficient in regeneration of shoots. Transformation with an Agrobacterium rhizogenes binary vector carrying the plasmid pBI 121.1 is reported. The percentage of cotransformation was estimated by testing GUS activity in hairy roots. The integration of Ri T-DNA and the NPTII gene in transformed plants was confirmed by molecular analyses and in vitro culture of transgenic tissues in the presence of kanamycin.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - 1AA indole-3-acetic acid - NAA -naphthaleneacetic acid - 2iP N⁶ – ² - PA proanthocyanidins - NOS nopaline synthase - NI TII neomycin phosphotransferase - GUS -glucuronidase - CaMV cauliflower mosaic virus     

Carbon isotope composition in relation to leaf gas exchange and environmental conditions in Hawaiian Metrosideros polymorpha populations

Summary Carbon isotope composition, photosynthetic gas exchange, and nitrogen content were measured in leaves of three varieties of Metrosideros polymorpha growing in sites presenting a variety of precipitation, temperature and edaphic regimes. The eight populations studied could be divided into two groups on the basis of their mean foliar ¹³C values, one group consisting of three populations with mean ¹³C values ca.-26 and another group with ¹³C values ca.-28. Less negative ¹³C values appeared to be associated with reduced physiological availability of soil moisture resulting from hypoxic conditions at a poorly drained high elevation bog site and from low precipitation at a welldrained, low elevation leeward site. Gas exchange measurements indicated that foliar ¹³C and intrinsic wateruse efficiency were positively correlated. Maximum photosynthetic rates were nearly constant while maximum stomatal conductance varied substantially in individuals with foliar ¹³C ranging from-29 to-24. In contrast with the patterns of ¹³C observed, leaf nitrogen content appeared to be genetically determined and independent of site characteristics. Photosynthetic nitrogenuse efficiency was nearly constant over the range of ¹³C observed, suggesting that a compromise between intrinsic water- and N-use efficiency did not occur. In one population variations in foliar ¹³C and gas exchange with leaf cohort age, caused the ratio of intercellular to atmospheric partial pressure of CO₂ predicted from gas exchange and that calculated from ¹³C to be in close agreement only in the two youngest cohorts of fully expanded leaves. The results indicated that with suitable precautions concerning measurement protocol, foliar ¹³C and gas exchange measurements were reliable indicators of potential resource use efficiency by M. polymorpha along environmental gradients.     

An investigation of the role of solutes in the xylem sap and in the xylem parenchyma as the source of root pressure

Summary Solute osmotic potentials (_x) in the vessels of hydroponically grown maize roots were measured to assess the osmotic-xylem-sap mechanism for generating root pressure (indicated by guttation). Solutes in vessels were measured in situ by X-ray microanalysis of plants frozen intact while guttating. Osmotic potentials outside the roots (_o) were changed by adding polyethylene glycol to the nutrient solution. Guttation rate fell when _o was decreased, but recovered towards the control value during 3–5 days when _o was greater than or equal to –0.3 MPa, but not when _o was equal to –0.4 MPa. In roots stressed to _o = –0.3 MPa, _x, was always more positive than _o, and _x changed only slightly (ca. 0.05 MPa). Thus the adjustment in the roots which increased root pressure cannot be ascribed to _x, contradicting the osmotic-xylem-sap mechanism. An alternative driving force was sought in the osmotic potentials of the vacuoles of the living cells (_v), which were analysed by microanalysis and estimated by plasmolysis. _v showed larger responses to osmotic stress (0.1 MPa). Some plants were pretreated with abundant KNO₃ in the nutrient solution. These plants showed very large adjustments in _v (0.4 MPa) but little change in _x (0.08 MPa). They guttated by 4 h after _o was lowered to –0.4 MPa. It is argued that turgor pressure of the living cells is a likely alternative source of root pressure. Published evidence for high solute concentrations in the xylem sap is critically assessed.Abbreviations _o external water potential - _x osmotic potential of xylem sap - _v osmotic potential of vacuolar sap - EDX energy dispersive X-ray microanalysis - CSEM cryo-scanning electron microscope - LN₂ liquid nitrogen - PEG polyethylene glycol     

‘Fine’ and ‘coarse’ mycorrhizal fungi on red clover plants in acid soils: Root colonization and plant responses

Three sterilized acid soils were inoculated with inocula of vesicular-arbuscular mycorrhizal fungi. Soils were limed and/or P fertilized to produce different fertility levels. Most inocula consisted of mixtures of fine + coarse type endophytes. Red clover (Trifolium pratense L.) was seeded in pots and grown in a glasshouse for 4 months. Root colonization by VAM fungi, the relative infection byGlomus tenue compared to that by coarse VAM fungi and the effect of inoculation on red clover growth and mineral nutrition (P, K, Ca and Mg) were studied. Spores were also checked and tentatively identified.Results showed that root colonization by VAM fungi was higher than 50% in most cases, the lower values being found in the soil with the highest P content. Inocula containingG. mosseae + G. tenue infected plant roots only in limed (pH>5.7) soils. A study of the relative colonization by fine and coarse endophytes showed that the competitive ability againstG. tenue followed the orderG. fasiculatum > G. mosseae > G. epigaeum > G. macrocarpum, although soil properties and fertility were crucial factors.Glomus lacteum was tentatively identified in two of the three experimental soils. The inoculum in whichGlommus tenue was most infective was also the most efficient in improving plant growth and nutrient uptake. The effect of inoculation on P and Mg uptake followed a similar pattern.     

Direct shoot organogenesis and plant regeneration from leaves of grape (Vitis spp.)

Adventitious shoots developed from in vitro-grown leaves of Vitis vinifera cultivars Cabernet Sauvignon, French Colombard, Grenache, Thompson Seedless (syn. Sultana) and White Riesling, V. rupestris cv. St. George (syn. du Lot) and V. vinifera × rupestris cv. Ganzin 1. Leaf explants less than 15 mm long were excised from nodal cultures and cultured on Murashige and Skoog or Nitsch and Nitsch-based regeneration media with 0, 1, 2 or 4 mgl^-1 6-benzylaminopurine (BAP). Adventitious shoots developed within 4 weeks at the petiolar stub and occasionally from wounded lamina tissues. Shoot organogenesis occurred only on media containing BAP and at a higher frequency with 2 mgl^-1 than with 1 or 4 mgl^-1. On media containing 2 mgl^-1 BAP, 47, 67, 60, and 42%, respectively, of leaf explants of Cabernet Sauvignon, French Colombard, Thompson Seedless, and White Riesling produced adventitious shoots compared to 14, 14, and 29%, respectively, for Grenache, St. George, and Ganzin 1. Solid culture medium was superior to liquid medium and transfer frequency on solid medium did not affect the regeneration frequency. Further shoot growth was promoted by the transfer of regenerating tissues to fresh regeneration medium. More than 80% of explants initially producing adventitious buds exhibited further shoot growth, developing an average of more than 6 shoots each. Shoots rooted easily and the resulting plants appeared morphologically identical to parent vines.     

Plant regeneration from hairy-root cultures transformed by infection with<Emphasis Type="Italic"> Agrobacterium rhizogenes</Emphasis> in<Emphasis Type="Italic"> Catharanthus roseus</Emphasis>

Hypocotyl explants of Catharanthus roseus produced hairy roots when cultured on Murashige and Skoog (MS) basal medium after infection by Agrobacterium rhizogenes. Explants gave rise to adventitious shoots at a frequency of up to 80% when cultured on MS medium supplemented with 31.1 M 6-benzyladenine and 5.4 M -naphthaleneacetic acid. There was a significant difference in the frequency of adventitious shoot formation for each hairy-root line derived from a different cultivar. Plants derived from hairy roots exhibited prolific rooting and had shortened internodes. Approximately half of the plants had wrinkled leaves and an abundant root mass with extensive lateral branching, but otherwise appeared morphologically normal. Plants with hairy roots that were derived from the cultivar Cooler Apricot developed flowers with petals that were white in the proximal region, whereas the wild-type flower petals are red. PCR and Southern blot analyses revealed that plants derived from hairy roots retained the Ri TL-DNA.Abbreviations BA 6-Benzyladenine - MS Murashige and Skoog medium - NAA -Naphthaleneacetic acid - SH Schenk and Hildebrandt mediumCommunicated by I.S. Chung     

Shoot,root and flower morphogenesis on tomato inflorescence explants

Regeneration of de novo shoots, roots and flowers has been obtained on inflorescence explants of tomato (Lycopersicon esculentum Mill.). Indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and -naphthaleneacetic acid (NAA) were added in a 3×3×3 factorial combination with kinetin, each at 0.001, 0.1 and 10 M concentrations. Direct shoot formation occurred on media with 10 M kinetin and 0.001 M IAA or NAA. Root formation was observed on media with 0.1–10 M IAA, IBA or NAA. Flower formation occurred on elongated shoots with several leaves on media with 10 M IAA and 0.1 M kinetin. Shoot organogenesis was increased by substituting 10 M zeatin or N⁶-benzyladenine (BA) for kinetin. Eleven tomato cultivars were tested for their ability to undergo de novo shoot regeneration on the improved medium. All tomato cultivars were capable of shoot morphogenesis with a mean number of shoots per explant that ranged from 1.3 (Red Alert) to 5.3 (Large Red Cherry). Histological studies revealed that active cell divisions occurred in subepidermal and cambial tisue during the first week of culture. Meristematic centers of dividing cells were evident by day 14, and well-developed shoot apices and leaf structures were observed on 50% of the explants 28 days after culture initiation.Abbreviations BA N⁶-benzyladenine - IAA Indole-3-acetic acid - IBA Indole-3-butyric acid - 2iP N⁶-[²-isopentyl]adenine - NAA -naphthaleneacetic acid - PGR plant growth regulator     

Effects of phytosulfokine-α on growth and tropane alkaloid production in transformed roots of Atropa belladonna

Phytosulfokine (PSK)- is a sulphated pentapeptide, isolated fromthe medium of cultured Asparagus officinalis mesophyllcells, that promotes cell proliferation. It is a putative key factor inconditioned medium required for the growth of low-density plant cell cultures.The present study investigates the effect of PSK- on growth and tropanealkaloid production in Atropa belladonna hairy rootstransformed with Agrobacterium rhizogenes (MAFF 03-01724). Although the growth rates ofhairy roots cultured in medium with orwithout PSK- for 4 weeks did not show any differences, the productivityof tropane alkaloids, especially of hyoscyamine, was enhanced by10^–7 or 10^–8 M PSK-. Inaddition, the content of tropane alkaloids in transformed roots treated withPSK- was 1.4 times higher than that of untreated roots after 4 weeks ofculture. The time course of growth and tropane alkaloid production inAtropa belladonna transformed roots suggested thatPSK- influenced the growth of transformed roots during the activegrowingphase, but not tropane alkaloid production.     

Nutrient transport between ryegrass plants differeing in nutrient status

Summary It is known that nitrogen and phosphorus can be transferred from one living plant to another, but it is not known whether the amounts transferred are large enough to influence the growth of the species in the field. Two Lolium perenne plants were grown per pot of unfertilized soil. During 25 weeks one plant (the donor) in each pot was fed nutrients through leaves; donors in control pots received only water. The receiver plants which shared a pot with the nutrient-fed donors increased significantly, compared with the controls, in leaf number and concentration of phosphorus, though not in concentration of nitrogen, potassium, calcium or magnesium. The rate of phosphorus transfer agreed well with previous results using ³²P. The results are compared with rates of phosphorus uptake in the field. It is concluded that nutrient transfer could have an influence on the balance between coexisting species in the field, but probably the influence will be small.