Retardation of tree growth by injection of plant growth regulators

Previously topped American sycamore (Platanus occidentalis L.), cottonwood (Populus deltoides Bartr. ex Marsh), water oak (Quercus nigra L.), and bigleaf maple (Acer macrophyllum Pursh) trees were injected with aqueous solutions of maleic hydrazide or dikegulac-sodium in April-June, 1979 at various locations around the United States. Measurements made later in the autumn showed that dikegulac-sodium reduced sprout regrowth in all four species, whereas maleic hydrazide was only effective in controlling regrowth of American sycamore and cottonwood. The effects of dikegulac persisted through the second growing season. Significant variability was observed among treated trees and must be reduced in order to achieve consistent growth responses from an application of growth retardants.This paper reports the results of research only. Mention of a growth regulator does not consitute a recommendation for use by the U.S. Department of Agriculture nor does it imply registration under FIFRA as amended. Mention of a trademark or propriety product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Cellular basis for dimethipin-induced loss of leaf turgor and desiccation

Dimethipin-induced increase in transpiration from kidney bean leaves (Phaseolus vulgaris L. cv. Black Valentine) was not correlated with stomatal aperture. From analysis of the kinetics of water loss from excised kidney bean leaves, it was concluded that the increase in transpiration was due almost entirely to an increase in the cuticular component. Both light and scanning electron microscopic analysis of dimethipin-treated leaves indicated that the first cells to be affected by dimethipin were the epidermal cells. These results suggest that dimethipin causes a loss of leaf turgor and desiccation by disrupting epidermal cells, thereby removing a major barrier for water loss from the leaf.Mention of trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Successive changes in the ultrastructure ofOryza sativa L. cells during growth and aging

Summary The ultrastructure ofOryza sativa L. cells in suspension was determined as cells developed, matured and senesced at 3, 10, and 17 days, respectively, after transfer to fresh medium. Although cultures of 3-day-old cells contained some senescent cells, the symptoms of cell aging were very conspicuous at 10 days and were most pronounced at 17 days. The amount of cytoplasm decreased as the number of lytic areas, myelin figures and vesicle bodies increased. Other noticeable subcellular changes observed were ultrastructural modifications of mitochondria, proplastids, amyloplasts, and nuclei. Such changes were associated with a general deterioration of the lipoprotein complex of the cell during its growth. A fibrous structure without an external membrane was observed and its reported for the first time for cells grown in suspension culture.Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Morphological changes incitrus associated with relatively high concentrations of paclobutrazol

Progressively higher concentrations of Paclobutrazol-markedly reduced germination of Valencia sweet orange (Citrus sinensis (L.) Osbeck) seed and induced significant changes in the morphology, growth, and development of roots of Valencia seedlings and rough lemon (C. limon (L.) Burm. f.) leaves. Threshold concentrations for significant visible effect to radical change ranged from 10³ to 10⁵ ppm (2.84×10^–4 to 2.84×10^–2 M) (ai). Initial change was readily evident in reduced lateral and fibrous root development at the lower concentrations (10³ ppm). Higher concentrations (10⁵ ppm) resulted in no secondary root formation and progressive basal enlargement terminating in a bulbouslike apex of the primary root. Lack of secondary roots suggests disruption in the pericycle or severe inhibition of meristematic initial cells. Root system changes were not visibly indicated in shoot growth other than strong inhibition of extensions.Mention of a trademark, warranty, proprietary product, or vendor does not constitute a guarantee by the U.S. Department of Agriculture and does not imply USDA approval to the exclusion of other products or vendors that may also be suitable.     

Identification of cytokinins in young wheat spikes (Triticum aestivum cv. Chinese spring)

Cytokinins in young wheat (Triticum aestivum cv. Chinese spring) spikes (2–15 mm) were isolated by immunoaffinity chromatography. High-performance liquid chromatography-radioimmunoassay and gas chromatography-mass spectrometry indicated that major cytokinins present weretrans-zeatin, ribosyl-trans-zeatin, ribosyldihydrozeatintrans-zeatin-9-glucoside, and the glucosides oftrans-zeatin, ribosyl-trans-zeatin, andtrans-zeatin-9-glucoside. Dihydrozeatin,iso-pentenyladenosine, andiso-pentenyladenine were also present but at lower concentrations.Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be suitable. R. C. Durley's present address is Biological Sciences, Monsanto Company, St. Louis, Missouri 63167.     

Influence of selected pesticides onGlomus species and their infection in citrus

Summary Four sterol inhibiting fungicides, two general biocides, and three nonfumigant nematicides were tested for their activity against the mycorrhizal fungi,Glomus intraradicas orG. mosseae. Of the four fungicides, propiconazole was the most inhibitory and triforine the least. These fungicides act systemically, and directly on the fungus in soil. One of the biocides, methylenebis-thiocyanate was toxic toG. mosseae, the other Bis-bromoacetoxy-2-Butene was not. All nematicides, aldicarb, fenamiphos and fensulfothion, had little or no inhibitory effect on the fungi.This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation by the U.S. Department of Agriculture nor does it imply registration under FIFRA.     

Positive identification of a lambda gt11 clone containing a region of fungal phytase gene by immunoprobe and sequence verification

Summary As the initial step in a project to provide a more cost-effective source of the phytase enzyme, this paper reports on the use of a polyclonal antibody raised to phytase purified from an isolate of Aspergillus niger (A. ficuum) to screen an A. niger lambda gt11 expression library and the use of amino acid sequencing to identify a clone containing part of the fungal phytase gene. The described use of amino acid sequence fragments to verify the cloning of a gene has potential applications in other cloning projects.Mention of a trademark or proprietary product does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be suitable Offprint requests to: E. Mullaney     

Direct screening for acid phosphatase production on bcip-agar plates

Summary A direct screening procedure for detection of acid phosphatase activity was established using medium containing 5-bromo-4-chloro-3-indolyl phosphate. Production of acid phosphatase could be suppressed by adding phosphate. This acid phosphatase activity as well as studying its regulation.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U. S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Response ofCitrus aurantium toGlomus etunicatus andG. Mosseae after soil treatment with selected fumigants

Summary In the test withGlomus mosseae and four fumigants, plant height in the SMD, NaN₃, and two highest rates of EDB was significantly less than height in the inoculated control. Vesicle formation was low but chlamydospore production suggested thatG. mosseae was least affected by EDB and DBCP. In the test withG. etunicatus and these fumigants, plant height was significantly less in the SMD treatments than in the inoculated check. Sporulation occured in all treatments; highestG. etunicatus chlamydospore numbers were in all EDB rates and the low rate of NaN₃. Significantly more vesicles formed in roots at the high DBCP rate, and significantly fewer formed in the SMD treatments and at the high rate of NaN₃ than the inoculated control. When DBCP and EDB-VAM tests were reexamined, neither EDB nor DBCP caused enhanced growth.This paper reports the results of research only. Mention of a pesticide, trade mark, proprietary product or vendor in this paper does not constitute a recommendation for use by the U.S. Department of Agriculture nor does it imply registration under FIFRA.     

Morphogenetic responses obtained from a variety of somatic explant tissues of data palm

Shoot tip, bud, leaf, stem and root explants from bearing trees, offshoots, seedlings, and asexual plantlets ofPhoenix dactylifera L. were cultured on modified Murashige and Skoog nutrient media containing 3 g/l activated charcoal, 100 mg/l 2,4-dichlorophenoxyacetic acid, 3 mg/l N ⁶-(Δ²-isopentyl)adenine to obtain callus. Differential morphogenetic responses were obtained from calli dependent on the explant type and parent source. Subcultured shoot tips and leafy lateral buds callus on nutrient media devoid of charcoal and supplemented with 0.1 mg/l α-naphthaleneacetic acid (NAA) produced adventitious plantlets. Subcultured leaf calli produced roots only. Root callus failed to exhibit any morphogenetic response upon subculturing. Undifferentiated non-leafy buds and stem tissues did not give rise to callus, regardless of the parent source. Generally, the best callus and embryogenetic responses from explants were obtained from seedling and plantlet parent sources. Similarly, organogenetic responses such as root formation and shoot development from shoot tips cultured on media containing 10 mg/l NAA were also related to the parent explant source. Mention of a trademark or proprietary product in the paper does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be available.     

Some effects of tentoxin on mature and developing chloroplasts

Tentoxin affected chloroplasts of all stages of development; it caused chlorosis of expanded and developing bean and lettuce leaves when introduced through the stem or roots and inhibited greening of etiolated lettuce seedlings. Cotyledons from 6-day-old lettuce seedlings grown in 10ug/ml tentoxin bad 50–68% of the monogalactosyldiglyceride and digalactosyldiglyceride content of healthy tissue whereas the sulfolipid, phospatidyl-glycerol, -ethanolamine, -choline and -inosrtol levels were unchanged. Toxin-treated tissue also showed selective increases in C-16 and C-18 saturated fatty acids.Research cooperative with the College of Agricultural and Life Sciences, University of Wisconsin, Madison, and the Agricultural Research Service, U.S. Department of Agriculture.Mention of companies or commercial products does not imply recommendation or endorsement by the U.S. Department of Agriculture over others not mentioned.     

Interstrain spheroplast fusion of Alternaria alternata

Summary Auxotrophic and drug resistant colonies of Alternaria alternata were selected following UV mutagenesis of spheroplasts and genetic transformation with pDH25. Intrastrain cell fusion of certain A. alternata parental strains induced by polyethylene glycol occurred at an average rate of 0.35%; interstrain fusions occurred at a rate of 0.08%. Mitotic recombination resulted from UV mutagenesis of spheroplasts from several fusants from 6hy1 × 1ar1. Fusants synthesized different levels of the cyclic tetrapeptide, tentoxin; some colonies produced higher levels than either parent. These results demonstrate that spheroplast fusion may have a potential application for genetic analysis of secondary metabolite production and for strain improvement in A. alternata.Mention of a trademark of proprietary product does not constitute a guarantee or warranty by the U. S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be suitable.     

Control of <Emphasis Type="Italic">In vitro</Emphasis> contamination of explants from greenhouse- and field-grown trees

Summary Controlling fungal and bacterial contamination of woody plant material can be extremely difficult. Isothiazolone biocides and sodium dichloroisocyanurate have been used singly and in combination to reduce microbial contamination in bud explants derived from greenhouse- and field-grown citrus trees. Explants from greenhouse-grown trees were effectively disinfested (<5% vs. 85% contamination) using a ‘standard’ disinfestation (SD) procedure followed by culture on medium containing 5 ml l⁻¹ Plant Preservative Mixture, or by the SD procedure but substituting 300 ppm sodium dichloroisocyanurate for 48 h for the treatment with 1.05% NaOCl in the SD procedure. Disinfestation of explants from field-grown trees was less effective than explants from the greenhouse, but was improved (10% vs. 47% contamination) by using a combination of the SD procedure with 1.05% NaOCl, or 100 or 300 ppm sodium dichloroisocyanurate followed by culture onto medium containing 5 ml l⁻¹ Plant Preservative Mixture. Mention of a trademark, warranty, proprietary product, or vendor does not constitute a guarantee by the US Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Callus formation from protoplasts of a maize cell culture

Summary A finely dispersed cell suspension culture from the friable callus of the Black Mexican Sweet line of maize was obtained. Protoplasts from this cell culture, when grown in a simplified medium described here, showed sustained cell divisions and gave rise to callus.Abbreviations 2,4-D 2,4-dichlorophenoxyaceticacid - SDS sodium dodecyl sulfate Cooperative Investigation, United States Department of Agriculture and Institute of Food and Agricultural Sciences, University of Florida, Florida Agricultural Experiment Station Journal Series No. 2453. Mention of a trademark, proprietary, product, or vendor does not constitute a guarantee or warrantly of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable     

Terpenoid precursors of strigol as seed germination stimulants of broomrape (Orobanche ramosa) and witchweed (Striga asiatica)

Strigol and some of its synthetic precursors and analogs are known to be germination stimulants for broomrape (Orobanche ramosa) and witchweed (Striga asiatica). Fifteen synthetic terpenoids, similar in structure to one of the four rings of the strigol molecule, were evaluated in two bioassays as seed germination stimulants with broomrape, and nine were found to be active. Five of the more active compounds contained ester groups. Whereas the study was intended primarily to evaluate forced germination of broomrape by aqueous solutions, the results are almost qualitatively identical for broomrape and witchweed. Monocyclic compounds with chemical structures similar to two of the rings of strigol have now been shown to possess significant bioactivity as germination stimulants.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Effect of EDTA on two RNases from wheat leaves

Two RNases, designated WL-RNase I and II, were separated fromextracts of senescing wheat leaves. WL-RNase II, but not WL-RNaseI, was inhibited by EDTA. A period of time was necessary forthe full effect of EDTA to be observed. Zinc ions abolishedthe EDTA effect. ¹Most of the data are taken from a Ph. D. Thesis submitted tothe University of London by L. SODEK. A portion of the workwas cooperative between the University of Illinois and the U.S.Dept. of Agriculture. Mention of a trademark or proprietaryproduct does not constitute a guarantee or warranty of the productby the U.S. Dept. of Agriculture, and does not imply its approvalto the exclusion of other products that may also be suitable ²Research Chemist, Crops Research Division, Agricultural ResearchService, United States Department of Agriculture (Received October 3, 1969; )     

Effect of paclobutrazol on accumulation of organic acids and total phenols in apple wood

Apple trees (Malus domestica Borkh Spartan grafted on MM 106 rootstock) planted in 1976 in an orchard at Beltsville, Maryland, were treated with paclobutrazol (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazol-1-yl-pentan-3-ol) using a foliage spray in 1982 and by trunk banding in 1983. Paclobutrazol did not inhibit shoot growth in 1983; however, shoot growth was significantly retarded in 1984. Increases in organic acids, including succinic, malic, citric, and quinic, and also in total phenols, occurred in wood produced in 1983 on paclobutrazol-treated trees when growth was not inhibited and in wood produced in 1984 when growth was inhibited. The organic acid content of both paclobutrazol-treated and untreated wood tended to decrease from the winter dormant period through growth resumption in the spring. However, the content of total phenols remained nearly the same throughout this sampling period.Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Phytotoxicity and transport of clopyralid from three formulations in honey mesquite

Foliar sprays of the monoethanolamine salt, oleylamine salt, and 1-decyl ester of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) were about equally effective in killing greenhouse-grown honey mesquite (Prosopis glandulosa Torr.). Treated leaves absorbed more clopyralid within 15 min after pipet application of the oleylamine salt compared to the other formulations. After 24 h, treated leaves absorbed and transported more clopyralid into the plant after application of the salt formulations compared to that of the 1-decyl ester. There were no consistent differences among clopyralid formulations in transport of clopyralid from foliar sprays at 4 h or 1, 3, or 8 days after treatment. Only the acid form of clopyralid was transported from the site of application of either ester or the amine formulation.This paper reports results of research only. Mention of trademark name of proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply their approval to the exclusion of other products that may also be suitable.     

Ultrastructure of primary sporidia of a wheat-bunt fungus,Tilletia caries,during ontogeny and mating

Summary Primary sporidia ofTilletia caries (DC.) Tul. are borne on denticles at the tips of promycelia. The promycelia contain many small vacuoles and mitochondria and numerous lipid bodies. As the primary sporidia develop, the promycelial cytoplasm passes into the nascent cells. Septa develop between the bases of mature sporidia and the tips of the denticles. Sporidia that abscise from the denticles commonly have prominent birth scars at their bases. The sporidia have very thin walls, few vacuoles, attenuated mitochondria, and numerous lipid bodies. Conjugation pegs are generally produced by both members of a conjugating pair of sporidia and there are bud scars where they emerge from the sporidia. The sporidial walls are apparently hydrolyzed during emergence of the pegs. Vesicles are sometimes present at the tips of the conjugation pegs and, before fusion, electron-dense accumulations are sometimes observed between the tips of adjacent pegs. The approaching conjugation pegs are precisely aligned prior to fusion, suggesting polar communication. The walls of the conjugation pegs fuse and then are hydrolyzed. Fused sporidia are relatively homogeneous in content. The nucleus in a sporidum is often close to the conjugation tube and occasionally is partly within the fusion tube.Cooperative investigations of the Oregon Agricultural Experiment Station, Brigham Young University, and Science and Education Administration-Agricultural Research, U.S. Department of Agriculture. Technical Paper No. 4,934 of the Oregon Agricultural Experiment Station. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.     

A new fumonisin from solid cultures of Fusarium moniliforme

A new fumonisin has been isolated from Fusarium moniliforme isolate MRC826 grown on corn. It was shown by NMR and mass spectrometry to be an isomer of fumonisin B₂ that has free hydroxyl groups at C-3 and C-10 instead of the normal C-3 and C-5. This new fumonisin was detected in cultures of most isolates of F. moniliforme that were examined and was usually present at concentrations similar to those of fumonisin B₂. Two isolates of F. moniliforme that produce significantly higher levels of this new isomer were identified.Abbreviations ELEM equine leukoencephalomalacia Mention of companies or products by name does not imply their endorsement by the US Department of Agriculture over others not cited.