The effect of nitrogen on the coumarin-induced tuberization of potato axillary shoots culturedin vitro

Coumarin-induced tuberization was studied on axillary shoots excised from etiolated potato sprouts each of which was cultured in vitro. Sprouts grown on culture medium with high nitrogen concentrations produced axillary shoots which elongated and would not readily tuberize. Sprouts cultured on medium low in nitrogen produced axillary shoots which tuberized with limited elongation. Carbohydrate concentration of the culture medium for the excised axillary shoot could significantly modify the nitrogen effect of the potato sprout medium. Axillary shoots growing on high nitrogen medium did not tuberize except in cases where the carbohydrate concentration was increased.     

An efficient technique for prolonged storage ofPhytophthora infestans

A decoction containing ‘Golden Bantam’ sweet corn is a suitable medium fqr prolonged maintance of the late blight organismPhytophthora infestons. Using this procedure, cultures of P.infestons were maintained up to 12 months without transferring. These isolates exhibited no variation in virulence or race.     

Norchief,a new smooth type,high total solids,red-skinned potato variety

Norchief is a medium late maturing, red variety with high total solids. In yield, the new variety is quite comparable to Red Pontiac and La Rouge but higher than Norland. Norchief has shown a certain degree of field tolerance to potato flea beetle,Epitrix cucumeris.     

Redsen: A new bright red-skinned potato cultivar

Redsen is a smooth, round, bright red-skinned potato cultivar with medium to high yield potential. It has resistance to race 0 of late blight (Phytophthora infestons) and is moderately resistant to some strains of silver scurf (Helminthosporium solanum) and common scab (Streptomyces scabies). The red color resists fading during storage and Redsen retains excellent marketability during storage.     

General characteristics of coumarin-induced tuberization of axillary shoots ofSolanum tuberosum L. culturedin vitro

Coumarin readily stimulates tuberization of cultured axillary shoots obtained from etiolated potato sprouts. Adequate concentrations of coumarin must be continuously present in the medium to effect tuber initiation. High nitrogen, gibberellic acid, abscisic acid, indole acetic acid, or naphthalene acetic acid reduced or inhibited coumarin-induced tuberization. Gibberellic acid and high concentrations of nitrogen in medium inhibited the uptake of coumarin-3-14C by the. axillary shoot. Based on the data of physiological activities by coumarin in other plant species and our data on tuberization, we propose that coumarin may represent in part the unknown inhibitor responsible for tuber initiation with reference to the inhibitor/gibberellic acid ratio theory of tuberization.     

Bison,a new red-skinned potato variety

Bison, a new red potato, was introduced by North Dakota State University. This new red variety has smooth tuber type and bright red skin color. Bison yields somewhat less than Norland and Red Pontiac but the advantage of Bison over these two varieties is its uniformity and bright red color. Bison is about medium in total solids and makes chips comparable in color to Norchip but lighter in color than Kennebec. Bison is resistant to race 0 of the late blight organismPhytophthora infestans, but susceptible to race 1–4.     

Mechanical and rheological properties of calcium carbonate-filled ethylene propylene diene elastomer reinforced by metallic acrylate salt

High performance ethylene propylene diene methylene elastomer (EPDM)/calcium carbonate (CaCO₃)/aluminum triacrylate (ALTA) hybrids have been prepared by a melt compounding process. The mechanical properties of the peroxide cured EPDM/CaCO₃/ALTA vulcanizates were investigated by tensile, hardness, resilience, abrasion and fatigue life tests. The results showed that the ALTA can greatly improve the modulus at 100 %, tensile strength, abrasion resistance and fatigue life of the EPDM/CaCO₃/ALTA vulcanizates, while retaining their high elongation at break. ALTA as a reactive filler had accelerating effect on the vulcanization reaction of and increased the crosslink density of the EPDM/CaCO₃ composites. This phenomenon is due to increasing the ionic bonds arise from both homo-polymerization of ALTA and graft co-polymerization of it onto the EPDM. Scanning electron microscopy (SEM) revealed the presence of ALTA causes to the roughness of the fracture surface of CaCO₃-filled EPDM compounds demonstrating high interaction between the fillers and EPDM improved by introduction of ALTA. Dynamic mechanical analysis revealed that the glass transition temperature (T _g ) and dissipation peak (tan δ) of EPDM composites decreases with increasing ALTA content. Decrease in tan δ value and inward shifting of T _g were related to improved interaction of filler and EPDM.     

Eradication of potato virus X from potato by ribavirin treatment of cultured potato shoot tips

Ribavirin treatment of cultured potato shoot tips was tested as a means of eradicating potato virus X (PVX) from two potato cultivars. Shoot tips were cultured on liquid medium containing 0, 1, 10 or 100μg/ml ribavirin. Cultures were evaluated periodically for viability, and scored for vigor on a relative growth scale. Developed plantlets were assayed for PVX by transmission tests toGomphrena globosa. Ribavirin treatment was phytotoxic at all tested concentrations, and lethal to all cultivars treated at 100 μg/ml. Treatment also delayed plantlet development by up to 2 months at 1 and 10 μg/ml as compared with nontreated controls. PVX assays indicated that 80 and 83% of the plantlets were free of PVX following treatment with 10 μg/ml for cultivars Russet Burbank and Red McClure, respectively. Five and 6% of the plantlets developed from the 1 μg/ml treatment were PVX-free, whereas 0 and 2% of the controls were PVX-free for the same cultivars. Six to 8 months were required to develop plants from shoot-tip cultures treated with 10 μg/ml ribavirin.     

Evaluation of Different Cooking Conditions on Broccoli (Brassica oleracea var. italica) to Improve the Nutritional Value and Consumer Acceptance

The objective of this study was to gain insights into the effect of the cooking method on the liking as well as the retention of glucosinolates in broccoli. With this knowledge it can be concluded whether the health aspects of broccoli be improved by the cooking method without deteriorating sensory perception. For this, broccoli was cooked by methods commonly applied by consumers: boiling with a cold (water) start; boiling with a hot (water) start; and steaming. Firmness, greenness and amount of total glucosinolates in cooked broccoli were instrumentally determined. Sensory evaluation by untrained consumers (n?=?99) for liking and sensory attributes intensity rating were performed on broccoli cooked by steaming and boiling-cold start at three time points, which resulted in ‘high’, ‘medium’, ‘low’ firm broccoli samples. At the end of cooking, steaming showed an increase in the amount of total glucosinolates (+17 %). Boiling-hot start (?41 %) and boiling-cold start (?50 %) showed a decrease in amount of total glucosinolates. Sensory evaluation did not show statistically significant differences between steaming and boiling-cold start in liking at ‘high’ and ‘medium’ firmness; and in the attribute intensity ratings (except for juiciness at ‘medium’ firmness, and flavour at ‘medium’ and ‘low’ firmness). This study demonstrates that medium firm broccoli showed optimum liking and that steaming compared to boiled-cold start showed higher amount of glucosinolates. It is concluded that the health aspects of broccoli can be improved without reducing the sensory aspects by optimising the cooking method.     

Phytophthora erythroseptica in Peru: Its identification and pathogenesis

EightPhytophthora isolates cultured from diseased potato plants and tubers in Peru were identified asPhytophthora erythroseptica Pethyb. var.erythroseptica. This pathogen was not previously reported from South America. The isolates were pathogenic to potato plants but they differed in virulence. Injuring roots prior to inoculation enhanced infection and disease development but all isolates infected noninjured roots. Continuous high soil moisture during incubation favored disease development. Under these conditions, disease developed at soil temperatures from 10 C to 30 C, but most rapidly at 25 C and 30 C. Plants grown 60 days before inoculation developed symptoms earlier and more rapidly than plants grown 15-, 30-, and 45 days. Four concentrations of mycelial-suspension inocula did not alter disease development, but zoospore inoculum induced symptoms and plant death more rapidly than mycelial suspensions at 25 C.     

Manufacture and performance of O-carboxymethyl chitosan sodium salt/cellulose fibers in N-methylmorpholine-N-oxide system

A series of O-carboxymethyl chitosan sodium salt (NaCMCh) with different degree of substitution (DS) of -CH₂COONa agent were successfully prepared by altering the reaction temperature and time. Both fourier transform infrared spectroscopy (FTIR) and ¹³C-Nuclear Magnetic Resonance (¹³C-NMR) were used to study the structure of NaCMCh. And the impact of DS on the antibacterial activity of NaCMCh was investigated. Then, the NaCMCh with optimal antibacterial activity was selected to prepare NaCMCh/cellulose fibers in N-methylmorpholine-N-oxide (NMMO) system. The structure, crystallization behavior, thermal property and morphology of obtained fibers were carefully studied with FTIR, Wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermal gravimetric (TG) and scanning electron microscope (SEM), respectively. Meanwhile, the antibacterial activity as well as mechanical properties of resultant fibers was also investigated. The results demonstrated that the fibers had strong antibacterial activity against Escherichia coli (E. coli), acceptable mechanical properties and good water retention.     

S-methyl-L-cysteine content of various legume meals

Total nitrogen, total sulphur and S-methyl-L-cysteine content of seed meals ofPhaseolus vulgaris, Vigna aureus, Vigna unguiculata, Phaseolus lunatus, Pisum sativum, Cajanus cajan, Vicia faba major,Vicia faba minor,Glycine max, Lupinus albus andSphenostylis stenocarpa, have been determined. The nutritional significance of the presence of S-methyl-L-cysteine is discussed, together with the role that this amino acid may play in interfering with the determination of methionine by cleavage with cyanogen bromide and subsequent gas-chromatographic identification of methyl thiocyanate.     

Purification of potato virus A and its detection in potato by enzyme-linked immunosorbent assay (ELISA)

Potato virus A (PVA) was purified fromNicandra physaloides by a simple method that omitted organic solvent clarification and consisted of differential centrifugation followed by equilibrium centrifugation in CsCl. An antiserum was produced that specifically detected PVA in potato leaf sap using either the SDS-agar test or enzyme-linked immunosorbent assay (ELISA). No heterlogous reaction of the antiserum with potato virus Y was detected. Purified PVA was highly infectious; it had an A 258/280 nm absorbance ratio of 1.28. The particles had a normal intact appearance in the electron microscope. Detection of PVA in potato sprouts and foliage by ELISA was compared with the local lesion assay onPhysalis angulata L. plants. ELISA was superior over an indicator plant test when sprout tissue was used. PVA antiserum reacted similarly with mild and crinkle isolates.     

Response of selectedSolanum species to virus eradication therapy

Thirty-fourSolanum genotypes infected with one or more potato viruses were evaluated in anin vitro virus eradication system combining heat therapy and the antiviral chemical ribavirin. This system was compared within vitro heat therapy or ribavirin treatment alone. The effect of expiant size on virus eradication following therapy was also evaluated. Infected plantlets were established in ribavirin lacking and amended medium; half of the plantlets in each medium were subjected to a 30-day heat treatment (35 C/31 C, 4-hr alternating periods), while the remaining plantlets were kept at room temperature (23 C). Following therapy, plantlets were tested quantitatively (OD at A₄₀₅) for the appropriate virus by enzyme linked immunosorbent assay (ELISA) and divided into 3 categories: low(< -0.05 OD), medium (> 0.05 to < 1.0 OD) and high (> -1.0 OD). Three plantlets were selected per group and further propagated as nodal cuttings or meristemtips. Regenerants which tested negative (< -0.05 OD) were transplanted to plug trays in a greenhouse and were retested after a 30-day grow-out period. Seventy-four and 91% of the genotypes yielded virus-free (VF) plants following propagation as nodal cuttings and meristem-tips, respectively. The combined therapies generated twice as many VF plants as thermotherapy alone and 5% and 15% more VF plants for nodal cutting and meristemtip derived plantlets, respectively, than for chemotherapy alone. Eleven of the 34 genotypes exhibited susceptibility to heat, but VF plants were obtained from survivors or by shortening the thermotherapy period. The efficiency of the system was enhanced by selecting plantlets for propagation which tested < -0.05 OD after treatment with 92%, 93%, 71%, and 100% of them remaining VF from potato viruses S, X, Y and leafroll, respectively. Twice as many VF plantlets were produced when treated plantlets were then propagated from meristem-tips than from nodal cuttings, but the rapid regeneration rate of plantlets from nodal cuttings makes it an attractive propagation method. Plantlet evaluation by ELISA after therapy to select plantlets with a high probability of producing VF plantlets and after further propagation to assure virus freedom are strongly recommended.     

Fungi associated with Collembola and mites isolated from scabby potatoes

Collembola and mites from the lesions of tubers infected with the acid scab organism were tested for the presence of fungal potato pathogens.Streptomyces spp. were found on and in the bodies of these arthropods.Verticillium albo-atrum was present on the external surface and in the body of the Collembola. Various other soil-inhabiting fungi which are not known to be potato pathogens and which were found on and in the bodies of these arthropods are noted.     

Reaction of potato tuber slices toPhytophthora infestans in relation to physiological age

Tuber resistance toPhytophthora infestans was studied in relation to physiological age in tubers of the cultivars Atzimba, Katahdin, Kennebec, and Sebago. Resistance to race1,2,3,4 was evaluated in freshly harvested tubers, and tubers stored at 5 C for up to 215 days. Atzimba tubers were highly resistant when freshly harvested but became increasingly susceptible as they aged physiologically. Tubers of the other three cultivars were susceptible when freshly harvested and also when aged. Further, 57 tuber selections from among 11 crosses initially gave resistant reactions. However, after storage for six months at 5 C, 26.3% of the selections remained resistant, 22.8% were moderately resistant, 31.6% moderately susceptible, and 19.3% fully susceptible.     

Enzymatic grafting of lactoferrin onto silk fibroins for antibacterial functionalization

Enzymatic oxidation of tyrosine side-chains in proteins could produce reactive o-quinones that might subsequently react with the primary amino groups of functional compounds, which provided a worthwhile reference for functionalization of fibrion materials. In the present work the potential for using tyrosinase to graft the bovine lactoferrin onto Bombyx mori silk fibroin was examined. Lactoferrin could adsorb onto silk fibers and covalently bind to the previous enzymatically oxidized fibroin surface. The enzyme-generated quinones in silk fibers also might cause self-crosslinking of fibroin peptides, which led to beneficial changes of silk properties. For the fabric treated with tyrosinase and lactoferrin slight improvements of dyeability and strength were obtained in comparison to the control. The combinedly treated fabric showed encouraging resistance to S. aureus and E. coli, the antibacterial activities reached to 87.0 % and 76.4 %, respectively. The durability of the antibacterial silk was noticeably higher than that of the sample treated with lactoferrin alone.     

Effect of inoculum concentration ofPhytophthora infestans on potato late blight

Zoospore suspensions ofPhytophthora infestans applied to potato cultivars in the field with an exponential inoculum sprayer resulted in defoliation within a range of severity that was log-normal with respect to inoculum concentration. Regression lines for different cultivars differed in position and, depending upon moisture conditions, slope, indicating that the cultivars differed in resistance to penetration and to invasion of tissue by the pathogen.     

Preparation and antibacterial properties of nanocomposite fibers made of polyamide 6 and silver-doped hydroxyapatite

Nanocomposite fibers of polyamide 6 (PA6) and hydroxyapatite (HA) were prepared and doped with silver to investigate antibacterial activities due to good potential for textile modification. Nano-sized HA could be synthesized using agarose and ethanol as thickener and washing medium, respectively. The PA6/HA nanocomposite fibers could be doped with silver by dipping the fibers having HA in aqueous AgNO₃ solution containing 300 ppm of Ag ion for 1 min utilizing HA as a carrier to load silver through ion-exchange mechanism. It was found that silver was successfully doped to PA6/HA nanocomposite fibers from the EDS spectra. The nanocomposite fibers containing 3.3 wt% of HA after silver doping demonstrated such excellent antibacterial activities against K. pneumonia and E. coli that they are expected to serve as functional antibacterial materials in various application fields.