Peripheral reticulum in chloroplasts of plants differing in CO2 fixation pathways and photorespiration

Summary The development of peripheral reticulum (PR) in chloroplasts varies in C₃ and C₄ plants. In general, PR is more extensive in C₄ plants, but PR is also seen in the chloroplasts of some C₃ plants. Within some C₄ plants, PR is seen in the bundle sheath cells which predominantly use the C₃ pathway. Thus, PR is not associated directly with the presence of the C₄ pathway on a cellular basis. Its predominance in C₄ plants must be related to some characteristic other than the method of CO₂ fixation. Ultrastructural evidence suggests that PR is associated with the rapid transfer of substances into and out of chloroplasts and from mesophyll to bundle sheath cells.Cooperative investigations of the Department of Agronomy, University of Georgia, Athens, Georgia; Department of Agronomy, University of Florida, Gainesville, Florida; and the Plant Science Research Division, Agricultural Research Service, USDA, Gainesville, Florida. The mention of specific products is for the purpose of clarity and does not imply endorsement by the USDA. Journal Series No. 977 of the Georgia Agricultural Experiment Station, and Journal Series No. 3870 of the Florida Agricultural Experiment Station.     

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.     

Plasmid-like DNAs associated with mitochondria of cytoplasmic male-sterile Sorghum

Summary Plasmid-like, linear DNAs were detected in preparations of mitochondrial DNA from cytoplasmic male-sterile sorghum. Designated N-1 and N-2, the DNAs exhibited molecular sizes of ca. 5,700 and 5,300 bp, respectively. The DNAs occurred in only the IS1112C entry among 24 entries examined. Electron microscopy of the DNAs indicated that the molecules were linear as isolated. Nick translation of N-1 and N-2 followed by membrane hybridization indicated substantial homology between the two DNAs, and some homology to the S-1 and S-2 maize plasmid-like DNAs. At least four additional DNA species, ranging from ca. 1,000–4,000 bp if linear, were also detected in sorghum mitochondrial DNA. The detection of plasmid-like DNAs in sorghum, with homology to the plasmid-like DNAs of maize, suggests an etiological relationship of the molecules to the inheritance and expression of cytoplasmic male sterility in sorghum, perhaps in a manner analogous to the postulated role of these elements in maize.Cooperative Investigations of Agricultural Research Service, U.S. Department of Agriculture, Institute of Food and Agricultural Sciences, University of Florida, Texas Agricultural Experiment Station, and Department of Genetics, North Carolina State University. Florida Experiment Stations Journal Series No. 3578     

Interspecific hybrids between kenaf ( Hibiscus cannabinus ) and roselle ( H. sabdariffa )

The successful interspecific cross is reported for the first time between kenaf (Hibiscus cannabinus L.), a diploid species (2n=36) and roselle (Hibiscus sabdariffa L.), a tetraploid species (2n=72). Kenaf, grown for its bast fiber and also under investigation as a source of paper pulp, is fast-growing and well adapted to mechanical harvesting, but susceptible to root-knot nematodes. Roselle, also grown for its bast fiber, is slower growing, not well adapted to mechanical harvesting, but certain varieties are resistant to root-knot nematodes. Five hybrid plants were produced from the pollination of 4,445 flowers of kenaf with pollen from roselle; no hybrid plants were produced from 2,655 pollinations made in the reciprocal direction. One line of roselle was the parent of 3 of the 5 hybrids; one line of kenaf was the parent of 2 of these 3. The F₁ hybrids were triploid, and varied in vigor, growth habit and vegetative morphology, but had similar flowers. Two of the F₁ hybrids showed high pollen fertility, apparently as a result of restitution at first meiotic division leading to unreduced spores. These two hybrids each produced a small amount of seed, which gave rise to an F₂ population of 22 plants. The F₂ plants vary in vigor but are morphologically uniform, have thick leaves with mosaic sectors, and are presumably spontaneous allohexaploids. The theoretical possibilities of increasing the percentage of recovery of the F₁ interspecific hybrids and of developing a synthesized hybrid variety useful for bast fiber and paper pulp are discussed. Research done cooperatively by Crops Research Division and Agricultural Engineering Research Division, Agricultural Research Service, U.S. Department of Agriculture (USDA), and the University of Florida Agricultural Experiment Station. Cytological investigations were carried out at the Department of Biological Sciences, Florida State University. Thanks are extended to the many individuals and organizations who supplied material for this study, and to M. Griffin Bell and E. Otho Richey, Agricultural Research Technicians, for their enthusiastic assistance.     

Isolation of viridicatin from Penicillium palitans

Summary Viridicatin, C₁₅H₁₁O₂N, has been shown to be a metabolic product of several fungi including P. palitans, P. olivino-viride, P. puberulum, P. martensii, P. crustosum, P. granulatum, and P. cyclopium. Although these strains also produce the tremorgenic mycotoxin, tremortin, no toxicity could be shown for viridicatin. Viridicatin does not appear to be a component of the tremortin molecule. A quantitative colorimetric assay has been developed for viridicatin.This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture. Mention of firm names or trade products does not imply that they are endorsed or recommended by the Department of Agriculture over other firms or similar products not mentioned.     

Plant nucleases. IV. Genetic control of ribonuclease activity in corn endosperm

Ribonuclease activity in the endosperms of 14 corn (Zea mays L.) inbreds ranged from 285 to 1305 units/g fresh weight 50 days after pollination. Activity is low in the inbred M14 and high in the inbred WF9. Hybrid endosperms contain intermediate levels of ribonuclease, and segregation occurs in the F₂ generation. The ribonuclease contents of the opaque-2 versions of nine inbred lines ranged from 1288 to 5110 units/g. The floury-2 mutation apparently does not affect ribonuclease content. Two or more genes may be involved in the control of ribonuclease content of developing endosperms.Cooperative investigations of the Plant Science Research Division, Agricultural Research Service, U.S. Department of Agriculture, and the Illinois Agricultural Experiment Station, Urbana, Illinois.     

The allotetraploidization of maize

Summary Allotetraploidization is the creation of synthetic allotetraploids. The allotetraploidization of maize can be accomplished by concentrating DPA (differential pairing affinity) factors into stocks by a recurrent selection breeding system. Selection is based on pairing configuration frequencies and altered genetic ratios that reflect DPA. Both an observed decline in the quadrivalent frequency per meiocyte from 8.10 to 7.31 and genetic data disclosing a reduction in the average frequency of recessive waxy (wx wx) pollen from Wx Wx wx wx plants from 17.48% to 13.35%, indicate considerable progress has been made toward allotetraploidization. A simple model for the effect of DPA on chromosome pairing and genetic ratios is presented.Contribution from the Agricultural Research Service, U.S. Department of Agriculture, University of Missouri, Missouri Agricultural Experiment Station, Journal Series No. 9806     

The physical location of fourteen RFLP markers in rice (Oryza sativa L.)

A biotin-labeled in situ hybridization technique was used in order to physically map RFLP markers to the chromosomes of rice (Oryza sativa L.). Fourteen RFLP markers, associated with the ends of the linkage groups on rice chromosomes 7, 8, 11, 12, were physically mapped onto specific regions of the chromosomes. The average detection rate of in situ hybridization was 5.91%. The markers were located on seven different chromosome arms. Ten of the fourteen markers were distributed near the chromosome ends. This demonstrated that the RFLP linkage groups involved covered a wide physical distance and that the centromeric region was bisected by all but one linkage group. Two markers covered a short genetic distance but were physically distant, while two covering a longer genetic distance were physically closer together. This indicates that considerable variation can, and does, exist between genetic and physical maps.This paper is a contribution of the U.S. Department of Agriculture, Agricultural Research Service, and Missouri Agricultural Experiment Station, Journal Series No. 11 882All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, or handicapThis paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the U.S. Department of Agriculture or the University of Missouri     

Linkages among zein genes determined by isoelectric focusing

Summary Genetic control of the major zein polypeptides in maize (Zea mays L.) was studied by isoelectric focusing (IEF) in agarose. Linkage relationships were determined by making a number of crosses, then determining the expression of zein polypeptides in backcross seeds. Chromosome linkages were determined by using the markers sugary-1 (for chromosome 4), yellow-8, and a waxy 7–9 translocation (for chromosome 7). Nine zeins were in one linkage group on chromosome 4, six in another linkage group on chromosome 4, and four zeins were in one linkage group on chromosome 7. Some IEF single bands consisted of at least two polypeptides, which were detected by subsequent sodium dodecyl sulfate polyacrylamide gel electrophoresis, by aberrant ratios in backcrosses, or by differing recombination percentages. One zein occurred only in homozygous sugary-1 seeds. Three sets of closely-linked zeins were noted that occurred together almost exclusively in certain inbreds.Cooperative investigations of the U.S. Department of Agriculture, Agricultural Research Service, and the Illinois Agricultural Experiment Station, Department of Agronomy, University of Illinois, Urbana, USAMention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned     

The aggregation states of spinach phosphoribulokinase

Phosphoribulokinase (PRK; EC 2.1.7.19) is active in illuminated chloroplasts and inactive in darkened chloroplasts. This regulatory mechanism is mediated by thioredoxin-dependent reduction of a kinase disulfide in vivo. Extracts of spinach (Spinacia oleracea L.) leaves in the presence of 10 mM dithiothreitol contain a single 80-kDa form of PRK as judged by gel filtration. Gel filtration of thiol-free extracts of light-harvested tissue shows the presence of two inactive forms of PRK, the 80-kDa form and an aggregate (> 550 kDa) form, but treatment of both forms with dithiothreitol restores kinase activity. Gel filtration following extraction of dark-harvested tissue in the absence of dithiotreitol demonstrates the presence of only the heavier form. Inclusion of 400 mM (NH₄)₂SO₄ in the homogenization buffer during extraction of light-harvested tissue suppresses the formation of the high-M _r form of PRK, but does not eliminate the aggregate form observed in extracts of dark-harvested leaves. However, prolonged treatment of extracts from dark-harvested tissue with 400 mM (NH₄)₂SO₄ results in conversion of the high-M _r form of phosphoribulokinase to the low-M _r form. The data are consistent with the heavier form of phosphoribulokinase being the normal in-vivo aggregation state in the dark, while the lighter form is the normal aggregation state in the light.This research was sponsored jointly by the science and education administration of the U.S. Department of Agriculture under Grant No. 88-37130-3722 from the Competitive Research Grants Office and by the Office of Health and Environmental Research, U.S. Department of Energy under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems Inc., Oak Ridge, Tenn., USA. The author is Postdoctoral Investigator supported by the U.S. Department of Agriculture through Subcontract No. 88-37130-3722 from the Biology Division of Oak Ridge National Laboratory to the University of Tennessee.     

Combined S2 and crossbred family selection in full-sib reciprocal recurrent selection

Summary A method (CRRS) that combines S₂ and crossbred family selection in full-sib reciprocal recurrent selection (FSRRS) is proposed. The method requires four generations per cycle in single-eared maize populations. Selection is based on performance of S₂ and full-sib families by applying selection index theory. Equations to estimate the coefficients included in the index are given. These estimates are functions of the genetic and phenotypic variances and covariances among and between the two kinds of families. Comparisons of FSRRS and CRRS under equivalent amount of effort show that CRRS has some advantage over FSRRS for low heritability of the trait being selected (e.g., maize yield) and when only one or two locations with two replications are involved in the selection experiment.Joint contribution: Institute Nacional de Investigaciones Agrarias, La Coruna, Spain; and Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, and Journal Paper No. J-10118 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA 50011. Project 2194     

Copper as essential to wheat reproduction

Summary The role of Cu in promoting the reproductive phase of growth was examined using Thatcher spring wheat (Triticum aestivum L.). Plants were grown in limed Bladen soil (pH 5.3) in a controlled growth room. The plants were first harvested when five leaves had developed (day 23) and some top leaves of Cu-deficient (-Cu) plants had rolled (withertip) indicating a Cu deficiency. The leaves were shorter on Cu than Cu-sufficient (+Cu) plants, and fewer leaves developed. As they entered the reproductive growth phase, +Cu plants accumulated reducing sugars and reduced 2, 3, 5- triphenyltetrazolium chloride (TTC) in their stems, while Cu plants had lower concentration of the reducing sugars and very little TTC was reduced indicating a reduction in energy and in reducing capacity. Thin-layer-chromatography showed that top leaves of Cu plants contained higher concentrations of aspartic acid, alanine, and serine; and less aminobutyric acid than +Cu plants. Nitrate, P, and K concentrations were higher, and Ca and Cu were lower in Cu than in +Cu plants.Contribution of U.S. Department of Agriculture, Agricultural Research Service, Plant Stress Laboratory, Northeast Region, Beltsville, MD 20705 and North Central Region, Department of Agronomy, University of Nebraska, Lincoln, NE 68583 as Paper No.5187, Journal Series, Nebraska Agricultural Experiment Station.Contribution of U.S. Department of Agriculture, Agricultural Research Service, Plant Stress Laboratory, Northeast Region, Beltsville, MD 20705 and North Central Region, Department of Agronomy, University of Nebraska, Lincoln, NE 68583 as Paper No.5187, Journal Series, Nebraska Agricultural Experiment Station.     

Growth characteristics of a continuous cell line from the velvetbean caterpillar,Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)

Summary The cell line UFL-AG-286 was established from the embryos ofAnticarsia gemmatalis (Lepidoptera: Noctuidae). The cell line was characterized by isozyme analysis and from molecular weight determination of the restriction endonuclease bands of the mitochondrial DNA. Cells seeded in 24-cluster wells had a doubling time of 5.9 d when seeded at 2×10⁵ cells ml and 6.7 d when seeded at 3×10⁵ cells/ml. This work was funded by U.S. Department of Agriculture grant 84-CRCR-1-1431. Florida Agricultural Experiment Station Journal Series, no. 8181.     

Effects ofFusarium solani naphthazarin toxins on the cytology and ultrastructure of rough lemon seedlings

Two naphthazarin phytotoxins (dihydrofusarubin and isomarticin) produced byFusarium solani were used to determine their effects on the cytology of leaves of rough lemon (Citrus jambhiri Lush) seedlings maintained in a dilute solution of the toxins. Dihydrofusarubin alone or in combination with isomarticin (80:20, v/v) caused cell necrosis above the midveins and lateral veins, plasmolysis or collapse of spongy mesophyll cells, collapse of phloem, depletion of starch, swelling of chloroplasts and disruption of cellular organization. At the ultrastructural level, the toxins affected chloroplast membranes by causing swelling, breaks in outer membranes, granal stack disorganization and swelling of intergranal membranes. The interstromal lamellae appeared as vesicles and sometimes as peripheral reticulum, with an increase in plastoglobuli. The tonoplast was broken or vesiculated. The only membranes not affected by the toxins were those of the nucleus and the mitochondria. This study establishes that the initial toxin effects of these fungal phytotoxins are on organellar membranes, primarily those of the chloroplasts, plasmalemma and tonoplast.Florida Agricultural Experiment Station Journal Series No. R-00648. This paper reports the results of research only. 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.     

Desiccated quiescent somatic embryos of orchardgrass for use assynthetic seeds

Summary Somatic embryos of orchardgrass became quiesent when desiccated to 13% water. Twelve percent germinated after 21 d of desiccated storage at 23° C and 4% developed into green plants. During desiccation, embryos decreased in size, became yellowish and brittle, and their outer walls collapsed. Within 15 min after imbibition, they rapidly enlarged and were indistinguishalbe from nondesiccated embryos. These results suggest that somatic embryos may be engineered to function as synthetic seeds for mass propagation. This research represents a collaborative effort between the Agricultural Experiment Stations of the University of Florida and the University of Tennessee. Research was supported in part by the Competitive Research Grants Office of the U.S. Department of Agriculture, grant 82-CRCR-1-1086, awarded to the University of Tennessee. Florida Agricultural Experiment Station Journal Series No. 7173.     

In-vitro induction of vegetative buds by benz(a)anthracene in tobacco callus

Summary Benz(a)anthracene induced vegetative buds on callus derived from stem tissue of haploid plants of Nicotiana tabacum a response similar to that obtained by a combination of kinetin and IAA.This study was carried out under Contract No. 12-14-100-10278 (5) with the Agricultural Research Service, U.S. Department of Agriculture, administered by the Eastern Utilization Research and Development Division, Philadelphia.     

Lipoxidase in early growth of wheat

Lipoxidase activity in etiolated wheat seedlings grown for 3.5days was localized primarily in the coleoptile and first leafof the seedling with moderate activity in the germinated seedand root. After 7 days growth, the distribution of lipoxidasewithin the plant did not change markedly while the total activitydecreased. The dormant wheat seed exhibited 2 major and 2 minor bands oflipoxidase activity on polyacrylamide gel zymograms. After germination,there was a marked change in the relative intensities of the4 lipoxidase bands depending on the part of the seedling assayed. ¹ Supported in part by funds from the Agricultural ResearchService, U. S. Department of Agriculture Grant No. 12-14-100-7654(74)administered by the Western Utilization Research and DevelopmentDivision, Albany, California. Published with the approval ofthe Director of the Wisconsin Agricultural Experiment Station. ² Present address: U. S. Department of Agriculture, NorthernGrain Insects Research Laboratory, Brookings, South Dakota 57006,U.S.A. ³ Present address: Institute of Experimental Phytopathologyand Entomology, Ivanka Pri Dunaji, Czechoslovakia.     

Libri novi

Summary The biological activity of sterigmatocystin towards mice, ducklings, and some microorganisms was determined. The LD₅₀ of sterigmatocystin for mice was in excess of 800 mg/kg. Aflatoxin B₁ was 125 times more toxic in the ducklings tests than was sterigmatocystin. The antibiotic disc assay demonstrated that 100 µg of sterigmatocystin did not inhibit any of the microorganisms tested.This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture.     

Effects of pH and other factors on the phosphate dependence of photosynthesis in spinach chloroplasts

Chloroplast stromal volume and pH influenced the phosphate (Pi)-dependence of photosynthesis of spinach (Spinacia oleracea L.) chloroplasts. Decreasing the sorbitol concentration in the reaction mixture from 0.35 to 0.25 M, or decreasing the external pH from 8.3 to 7.3, extended the induction period of photosynthesis and decreased both the optimal [Pi] and the minimal [Pi] required to inhibit O₂ evolution completely. At least part of the effect of external pH was attributable to changes in stromal pH on the basis of effects of NH₄Cl and sodium acetate at a constant external pH. When the external pH was increased from 7.3 to 8.3, the stromal pH changed only about 0.6 pH units. Hence, the pH gradient across the envelope was diminished and the efflux of phosphoglycerate relative to dihydroxyacetone phosphate was enhanced.Calvin-cycle activity, varied with light intesity or electron transport inhibitors, affected the rate of photosynthesis but not the induction period or the Pi optimum for photosynthesis. Relatively low Calvin-cycle activity was apparently sufficient to fill metabolite pools and thus terminate the induction period. The results indicate that pH does not affect the Pi dependence of photosynthesis by reducing Calvin-cycle activity. Rather, it is postulated that at low stromal pH, larger metabolic pools are required to maintain maximum rates of photosynthesis because of changes in substrate affinity of some Calvin-cycle enzymes. Consequently, chloroplast photosynthesis would be more sensitive to exogenous Pi.Abbreviations DHAP dihydroxyacetone phosphate - PGA 3-phosphoglycerate - Pi inorganic phosphate Cooperative investigations of the North Carolina Agricultural Research Service and Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Raleigh, N.C. Paper No. 6391 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, N.C., USA     

Genetic control of sucrose synthetase in maize endosperm

Summary Sucrose synthetase activity in endosperm extracts of seven shrunken(sh) mutants of spontaneous origin and three similar mutants due to the association of the controlling element Ds with the Sh locus is examined. A residual level of 3 to 5% as compared to the normal (Sh) endosperm is seen in all the mutants. The residual activity is similar to that of the Sh locus encoded endosperm sucrose synthetase by several criteria including an identical size of polypeptides and a similarity in antigenic properties. These two enzymes are, however, distinguishable by a slight difference in electrophoretic mobility in native gels and a difference in the relative abundance of enzyme molecules. The latter property is a reflection of a marked difference seen in the developmental profile of enzyme activity in the two genotypes. The earlier hypothesis (Chourey and Nelson 1976) that these two sucrose synthetases are encoded by two separate genes is strengthened by: (a) the presence of the residual enzyme in a sh deletion mutant and (b) an electrophoretic demonstration of two proteins, corresponding to the major and minor sucrose synthetase proteins, in the wild type (Sh) genotype. The two sucrose synthetase genes seem to provide a model system in plants for studying the molecular basis of temporal specificity of genes.Cooperative Investigation, United States Department of Agriculture and Institute of Food and Agricultural Sciences, University of Florida, Florida Agricultural Experiment Station Journal Series No. 3288. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty 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