Effect of seaweed concentrate on the growth and mineral nutrition of nutrient-stressed lettuce

The effects of the seaweed concentrate Kelpak on the growth and mineral nutrition of lettuce plants grown under conditions of varying nutrient supply were investigated. Kelpak significantly increased the yield and the concentration and amounts of Ca, K and Mg in the leaves of lettuce receiving an adequate supply of nutrients, but had little effect on nutrient stressed plants. Results are discussed in relation to the physiological mechanisms that have been proposed to explain the beneficial effects of seaweed concentrate on plants.author for correspondence     

The effect of seaweed concentrate on the growth and yield of potassium stressed wheat

The effects of the seaweed concentrate “Kelpak’ on the growth and yield of wheat grown under conditions of varying K supply were investigated. Kelpak had no significant effect on the yield of wheat receiving an adequate K supply, but significantly increased the yield of K stressed plants. The increase in yield was caused by an increase in both grain number and individual grain weight. Although the beneficial effects of seaweed concentrates have often been attributed to their cytokinin content, several lines of evidence suggested that this group of plant growth regulators may not be solely responsible for the observed effects of Kelpak on wheat. Irrespective of the physiological mechanism of action, Kelpak would appear to have considerable potential for increasing yield in K stressed wheat and may therefore reduce the requirement of wheat for K fertilization.     

Effect of seaweed concentrate on the establishment and yield of greenhouse tomato plants

Seaweed concentrate prepared fromEcklonia maxima (Osbeck) Papenfuss, when applied as a soil drench, significantly improved the growth of tomato seedlings. Application as a foliar spray had no effect on young plants. In a second experiment SWC-treated plants exhibited early fruit ripening and a total fruit fresh weight increase of 17%. The number of harvested fruit were improved by about 10%. In this instance foliar applied SWC was more beneficial than SWC applied to the soil. The significance of these findings is discussed.author for correspondence     

Effect of seaweed concentrate fromEcklonia maxima (Osbeck) Papenfuss onMeloidogyne incognita infestation on tomato

Seaweed concentrate (SWC), prepared fromEcklonia maxima, when applied as a soil drench to tomato seedlings, significantly increased plant growth and reduced infestation byMeloidogyne incognita. Foliar applied SWC had little effect on plant growth and increased nematode galling. Ashing SWC reduced the suppressive effect on nematode infestation. In anin vitro experiment, SWC lessened infestation of root-knot nematodes on excised roots of a susceptible cultivar of tomato. Application of the same concentrations of SWC to a nematode-resistant cultivar increased the number of egg masses.     

Fertile,intermediate hybrids between Phaseolus vulgaris and P. acutifolius from congruity backcrossing

Summary Recurrent or introgressive backcrossing of Phaseolus vulgaris — P. acutifolius hybrids with either P. vulgaris or P. acutifolius increased fertility, as measured by pollen stainability and seed per pod from non-manipulated flowers, while invariably resulting in loss of traits from the non-recurrent parent. When hybrids were backcrossed with each of the parent species in alternate generations (congruity backcrossing), fertility decreased in early generations but gradually increased in later generations. By the fourth or fifth generation, congruity-backcross hybrids produced numbers of seeds per pod from non-manipulated flowers comparable to those of parent species, although the percent of stainable pollen tended to be lower. Congruity-backcross hybrids were intermediate to parent species when pedigrees contained equal representation of parents but favored the majority parent when pedigrees were unbalanced. Individuals exhibiting symptoms of developmental incongruity, such as abnormal leaflet number, foliar variagation, or unusual growth patterns, occurred in each generation. However, completely new characteristics appeared after the second backcross generation, presumably due to recombination. Backcrossing to both parent species in alternate generation reversed incongruity, allowing selection for fertility without loss of traits from one of the parent species.Scientific Journal Series Paper Number 15, 671 of the Minnesota Agricultural Experimental Station     

Effect of seaweed concentrate on growth and development of the marigoldTagetes patula

The seaweed concentrate Kelpak, made fromEcklonia maxima, and applied as a foliar spray or a root drench at transplanting, improved both the vegetative and reproductive growth of marigolds. Of particular significance is that the overall production of seeds (fruits) was increased by as much as 50% in some instances. Very low concentrations of seaweed concentrate were not always effective, while the higher dosages decreased vegetative growth.     

Regeneration from long-term cell suspension cultures of tepary bean (Phaseolus acutifolius)

Plant regeneration has been achieved from long-term cell suspension cultures established from leaf derived callus of tepary bean (Phaseolus acutifolius). The proportion of densely cytoplasmic cells in suspension culture increased when cultured in the L-6 medium with 54 M NAA and 2 M KN. Filtration of the cells at each of five consecutive subcultures resulted in the isolation of a plant regenerating cell line (TB 686), which is being maintained in L-6 medium with 4.5 M 2,4-D and 2.3 M zeatin. Differentiated green cell aggregates were obtained when cells from maintenance medium were transferred to the same medium with 10 M BA. Embryo-like structures developed from these aggregates on L-6 medium with 2.3 M zeatin, 0.69 M GA₃ and 1.5 M NAA. Plantlets regenerated from these structures when they were cultured on L-6 medium with 7.0 M NAA and 1.0 M KN. Plant regeneration from the cell line remained relatively constant for 270 days. Regenerated plants were grown to maturity in the greenhouse.Abbreviations BA Benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ Gibberellic acid - IPA Isopentenyladenine - KN Kinetin - NAA Naphthaleneacetic acid - AA Amino acid medium (Toriyama and Hinita, 1985) The research was sponsored by United States Agency for International Development, Washington D.C., Cooperative Agreement DAN-4137-A-00-4053-00     

Dehydration-induced alterations in growth and osmotic potential of callus from six tepary bean lines varying in drought resistance

Growth and osmotic potential of calli induced from leaf- and root-derived tissues of six tepary bean lines (Phaseolus acutifolius) varying in drought resistance were assessed in vitro after polyethylene glycol-induced (10%, PEG-10,000) dehydration. Calli of resistant teparies were characterized by low initial osmotic potential (ψ_s) and relative growth rate (RGR) on medium lacking PEG (−0.30 MPa). However, calli of both resistant and sensitive lines were similar in dry matter percent (DM). Presence of PEG in the medium (−0.58 MPa) elevated DM in all teparies except one resistant line. Both leaf- and root-derived calli of sensitive teparies exhibited osmotic adjustment (OA) but reduced RGR that remained after rehydration in one line. We concluded that preexisting force of low cellular ψ_s rather than induced OA plays an important role in buffering adverse effects of dehydration and conditioning drought resistance of tepary beans. This information may aid Phaseolus breeders in screening for drought resistance among large number of accessions.     

Qualitative and quantitative characterization of RAPD variation among snap bean (Phaseolus vulgaris) genotypes

Ten snap bean (Phaseolus vulgaris) genotypes were screened for polymorphism with 400 RAPD (random amplified polymorphic DNA) primers. Polymorphic RAPDs were scored and classified into three categories based on ethidium bromide staining intensity. An average of 5.19 RAPD bands were scored per primer for the 364 primers that gave scorable amplification products. An average of 2.15 polymorphic RAPDs were detected per primer. The results show that primer screening may reduce the number of RAPD reactions required for the analysis of genetic relationships among snap-bean genotypes by over 60%. Based on the analysis of the distribution of RAPD amplification, the same number of polymorphic RAPDs were amplified from different genotypes for all RAPD band intensity levels. A comparison of RAPD band amplification frequency among genotypes for the three categories of bands classified by amplification strength revealed a measurable difference in the frequencies of RAPDs classified as faint (weakly amplifying) compared to RAPD bands classified as bold (strongly amplifying) indicating a possible scoring error due to the underscoring of faint bands. Correlation analysis showed that RAPD bands amplified by the same primer are not more closely correlated then RAPD bands amplified by different primers but are more highly correlated then expected by chance. Pairwise comparisons of RAPD bands indicate that the distribution of RAPD amplification among genotypes will be a useful criterion for establishing RAPD band identity. For the average pairwise comparison of genotypes, 50% of primers tested and 15.8% of all scored RAPDs detected polymorphism. Based on RAPD data Nei's average gene diversity at a locus was 0.158 based on all scorable RAPD bands and 0.388 if only polymorphic RAPD loci were considered. RAPD-derived 1 relationships among genotypes are reported for the ten genotypes included in this study. The data presented here demonstrate that many informative, polymorphic RAPDs can be found among snap bean cultivars. These RAPDs may be useful for the unique identification of bean varieties, the organization of bean germplasm, and applications of molecular markers to bean breeding.     

Effect of fungicides on survival of Rhizobium on seeds and the nodulation of bean (Phaseolus vulgaris L.)

The survival of Rhizobium leguminosarum biovar phaseoli on seeds of bean was tested, using the cultivar Carioca. The seeds were treated seven days before inoculation with Benlate, Vitavax, Banrot, Difolatan or Ridomil fungicides. The rhizobial strains used were: CIAT 899, CPAC 1135 and CIAT 652. Strain CIAT 899 showed greater survival on the seed with fungicide than the other strains. Two hours after the contact with fungicides strains CIAT 652 and CPAC 1135 had significantly lower numbers of rhizobia than the treatment without fungicide. The Benlate and Banrot fungicides had the greatest effect on survival of rhizobial strains. There was a drastic mortality of the two strains, CIAT 652 and CPAC 1135, on seeds treated with Benlate and Ridomil. Under field conditions, granular inoculation produced fewer nodules, but a similar total nodule weight as seed inoculation. Serological tests (ELISA) showed that seed treatment with Benlate in connection with seed inoculation reduced drastically the occurrence of inoculated strains in nodules, while the same fungicide treatment and inoculation applied in the seed furrow did not affect the survival of the inoculated strain.     

Nodule conductance varied among common bean (Phaseolus vulgaris) genotypes under phosphorus deficiency

Common bean genotypes BAT477, COCOT, DOR364, Flamingo, and NAG310 were inoculated with Rhizobium tropici CIAT899 and grown under phosphorus deficiency. This treatment induced a significant decrease in shoot and nodule growth that varied among genotypes from 35% to 57% and from 45% to 61%, respectively, whereas root biomass was less affected. Phosphorus deficiency affected differently the genotypes for nodule number and size, and the responses of nodulated-root O2 uptake (Conr) to raising rhizospheric PO2. From the later data, nodule conductance could be computed by dividing the slope of the regression of Conr as a function of external pO2 by nodule surface area. It is concluded that differences in nodule conductance are related to genotypic tolerance to P deficiency.     

Changes in cytokinin and auxin concentrations in seaweed concentrates when stored at an elevated temperature

Two seaweed concentrates were made from the kelps Ecklonia maxima and Macrocystis pyrifera using a cell burst method. Cytokinin- and auxin-like activities were measured using the soybean callus and mungbean bioassays, respectively. Cytokinin-like activity was detected in both seaweed concentrates, being equivalent to approximately 50 μg L⁻¹ kinetin. Auxin-like activity was also detected in both concentrates with the E. maxima derived concentrate having higher biological activity, equivalent to 10⁻⁵–10⁻⁴ M indole-butyric acid. Two replicates of each concentrate were stored at 54 °C for 14 days to accelerate the effects of storage. Both fresh and stored samples of the two seaweed concentrates were analysed for their endogenous cytokinin and auxin content. The samples were purified using a combined DEAE-Sephadex octadecylsilica column and immunoaffinity chromatography based on wide-range cytokinin and IAA specific monoclonal antibodies. These extracts were analysed by HPLC linked to a Micromass single quadrupole mass spectrophotometer. Eighteen and nineteen different cytokinins were detected, respectively, in the two concentrates, with trans-zeatin-O-glucoside being the main cytokinin present. Accelerated storage of the concentrates caused an increase in the total cytokinin concentration with a large increase in the aromatic meta-topolin. Indole-3-acetic acid was the main auxin in both seaweed concentrates. Indole conjugates, including amino acid conjugates, were also quantified. The total auxin concentration decreased with accelerated storage for both concentrates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Purification and characterization of two alpha-amylase inhibitors from seeds of tepary bean (Phaseolus acutifolius A. Gray)

Two proteinaceous alpha-amylase inhibitors termed alphaAI-Pa1 and alphaAI-Pa2 were purified from seeds of a cultivated tepary bean (Phaseolus acutifolius A. Gray, cv. PI311897). The two inhibitors differed in their specificity towards alpha-amylases of insect pests such as bruchids, although neither showed any inhibitory activity against alpha-amylases of mammalian, bacterial or fungal origin. AlphaAI-Pa2 resembles two common bean inhibitors, alphaAI-1 and alphaAI-2, in several characteristics such as N-terminal amino acid sequences and oligomeric structure being composed of alpha and beta subunits. In contrast alphaAI-Pa1 is composed of a single glycopolypeptide with a molecular mass of 35 kDa, and its N-terminal amino acid sequence resembled that of seed lectins in tepary bean and common bean. The information on the two tepary bean alpha-amylase inhibitors may be useful not only for providing insight into critical structure for the specificity towards different alpha-amylase enzymes but also for enhancing insect resistance in crops.     

Plant regeneration from seedling explants of green bean (Phaseolus vulgaris L) via organogenesis

Green bean (Phaseolus vulgaris L.) plants were regenerated from 3-day old seedling explants via organogenesis. The explants contained a cotyledon and a small portion (2–3 mm) of embryonic axis split in half. Explants were cultured on a defined medium containing glutamine as the sole nitrogen source. A ring of meristematic tissue was produced at the base of the axillary bud located at the cotyledonary node. The meristematic tissue was produced only if the axillary bud was present together with the cotyledon in the explant. Buds and shoots developed from the meristematic ring. Selected shoots produced roots when excised from the cluster of buds and transferred to root induction medium. Rooted shoots (plantlets) grew well and produced viable seeds when grown in the greenhouse. Histological studies revealed the origin of buds from the peripheral layers of the meristematic ring.Production of buds and shoots was a continuous process, so that new shoots could be removed from the explant for plantlet production every 10–14 days. With the cultivar Dark Red Kidney, an average of 49 buds and 8 shoots were regenerated per explant by 30 days after culture initiation. Sixty-seven percent of the shoots produced roots, and 90–95% of the plantlets survived greenhouse acclimatization to produce healthy plants.     

Plant regeneration from embryo-derived callus in Phaseolus vulgaris L. (common bean) and P. acutifolius A. Gray (tepary bean)

Regeneration-competent callus of Phaseolus vulgaris and P. acutifolius was obtained from mature embryo explants on a medium containing thidiazuron and indole-3-acetic acid. For the P. vulgaris genotype Xan-159, regeneration was achieved from cotyledon explants, but not from embryonic axis explants. Both explants could be used for the P. acutifolius genotype NI 574 but embryonic axes gave the best results. In-vitro-rooted plantlets of P. acutifolius could readily be established in the greenhouse. For P. vulgaris hardening problems with in-vitro-rooted plantlets could be overcome by means of in vitro grafting. The potential of the described procedure for obtaining transgenic P. vulgaris plants is discussed. Received: 31 July 1997 / Revision received: 9 September 1997 / Accepted: 22 December 1997     

Effects of ethylene and inhibitors of ethylene synthesis and action on nodulation in common bean (Phaseolus vulgaris L.)

The ethylene releasing compound, 2-chloroethylphosphonic acid (ethephon) inhibited nodule development in common bean (Phaseolus vulgaris L.) plants. In contrast, inhibitors of ethylene synthesis or its physiological activity enhanced nodulation. In a co-culture of bean seeds and rhizobia, ethephon inhibited rhizobial growth while inhibitors of ethylene synthesis or action did not influence the growth and proliferation of rhizobia. These data emphasize the role of ethylene as a regulator of nodulation in determinate nodulators and indicate that the ethylene signaling pathway involved in the nodulation process is not limited to the plant host but also involves the bacterial symbiont.     

Molecular composition and surface properties of storage lipid particles in wax bean (Phaseolus vulgaris)

Lipid particles have been isolated from seeds of wax bean (Phaseolus vulgaris), a species in which starch and protein rather than lipid are the major seed storage reserves. These lipid particles resemble oil bodies present in oil-rich seeds in that > 90% of their lipid is triacylglycerol. Moreover, this triacylglycerol is rapidly metabolized during seed germination indicating that it is a storage reserve. The phospholipid surfaces of oil bodies are known to be completely coated with oleosin which prevents their coalescence, particularly during desiccation of the developing seed. This would appear to be necessary since lipid is the major storage reserve in oil seeds, and there are very few alternate types of storage particles in the cytoplasm of oil seed endosperm to provide a buffer against coalescence of oil bodies by isolating them from one another. The present study indicates that the surfaces of lipid particles from wax bean are not completely coated with oleosin and feature regions of naked phospholipid. This finding has been interpreted as reflecting the fact that lipid particles in wax been seeds are less prone to coalescence than oil bodies of oil-rich seeds. This arises because the individual lipid particles are interspersed in situ among highly abundant protein bodies and starch grains and hence less likely to come in contact with one another, even during desiccation of the developing seed.     

Molecular cloning of the cDNA encoding a stress-inducible protein phosphatase 1 (PP1) catalytic subunit from French bean (Phaseolus vulgaris L.)

A cDNA showing high sequence similarity (>70%) to plant protein phosphatase 1 catalytic subunit variants from other species has been isolated from a cDNA library derived from mRNAs expressed in elicitor-treated suspension-cultured cells. The clone appears to be a near full-length 1431 bp with a 172 bp 5-untranslated region and a 317 bp 3-untranslated region. The open reading frame, determined by sequence similarity, codes for a protein with predicted M _r of 35552. Alternatively an ATG situated to the 5 end of the putative start site would increase the protein size by 6 amino acids.The mRNA for Pvpp1 was shown to be rapidly induced by elicitor treatment of suspension-cultured cells of French bean. The cloned cDNA represents one of the few examples of a gene product that is probably involved in dephosphorylation events arising after the initial responses to biotic stress.Abbreviations PAL phenylalanine ammonia-lyase - PP1 protein phosphatase 1 - Pvpp1 Phaseolus vulgaris protein phosphatase 1     

Effect of seaweed concentrate on hydroponically grown spring barley

Spring barley (Hordeum vulgare cv. Triumph) was grown hydroponically over a 6-week period. Two treatments were incorporated either into the hydroponic solution or sprayed onto the plants at rates of 1 ml per 3 litres. The treatments applied were: (i) a seaweed concentrate prepared fromAscophyllum nodosum (L.) Le Jolis (marketed as Maxicrop Triple), (ii) a ‘Trace element’ treatment incorporating the micro and macro nutrients added to the seaweed extract base to produce the formulated product Maxicrop Triple and (iii) a control treatment. Irrespective of the mode of application, plants treated with Maxicrop Triple grew faster than plants under either of the two other treatments. Elevated growth rates were also found for the ‘Trace element’ treated plants when incorporated into the hydroponic solution. At the final harvest, plants with Maxicrop Triple incorporated into the hydroponic solution showed increases from 56–63% over the control treatment for the growth characteristics measured. ‘Trace element’-treated plants produced increases of between 25–45%. When the treatments were sprayed the effect was less pronounced. Maxicrop Triple increased growth characters by 35–38% and the ‘trace element’ treatment gave increases in the range of 2–13%.     

Susceptibility of dry bean (Phaseolus vulgaris L.) to Agrobacterium infection: Transformation of cotyledonary and hypocotyl tissues

A germinating-seed assay was developed to determine the susceptibility of dry bean (Phaseolus vulgaris L.) to infection by Agrobacterium tumefaciens. Seedlings infected one to three days after germination were more susceptible to A. tumefaciens infection than seedlings germinated for five to seven days and the galls that formed on the one to three day seedlings were significantly larger. Nineteen genotypes of dry bean were screened with this assay and all were equally susceptible to nopaline, octopine and agropine biotypes of A. tumefaciens. In addition, cotyledonary nodes and hypocotyls of P. vulgaris were inoculated with disarmed strain A. tumefaciens strain C58Z707 and the avirulent A. rhizogenes strain A4RS (pRiB278b), respectively. Both strains contain the binary plasmid pGA482 which has the neomycin phosphotransferase II (NPT II) gene nested between T-DNA borders. From these infected tissues, callus and root tissues, respectively capable of growing in the presence of kanamycin were obtained. These tissues displayed NPT II activity and integrated copies of the NPT II gene were detected from putative transformed root cultures by genomic blot hybridization.