Folke Skoog

Bio: Folke Skoog is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Callus & Kinetin. The author has an hindex of 47, co-authored 141 publications receiving 71619 citations. Previous affiliations of Folke Skoog include California Institute of Technology & Johns Hopkins University.

A revised medium for rapid growth and bio assays with tobacco tissue cultures

Abstract: In experiments with tobacco tissue cultured on White's modified medium (basal meditmi hi Tnhles 1 and 2) supplemenk'd with kiticthi and hidoleacctic acid, a slrikin^' fourlo (ive-told intTease iu yield was ohtaitu-d within a three to Tour week j^rowth period on addition of an aqtteotis exlrarl of tobacco leaves (Fi^'ures 1 and 2). Subse(iueutly it was found Ihiit this jnoniotiou oi' f^rowih was due mainly though nol entirely to inorj^auic rather than organic con.stitttenls in the extract. In the isolation of Rrowth factors from plant tissues and other sources inorj '̂anic salts are fre(|uently carried along with fhe organic fraclioits. When tissue cultures are used for bioassays, therefore, il is necessary lo lake into account increases in growth which may result from nutrient elements or other known constituents of the medium which may he present in the te.st materials. To minimize interference trom rontaminaitis of this type, an altempt has heen made to de\\eh)p a nieditmi with such adequate supplies of all re(iuired tnineral nutrients and cotntnott orgattic cottslitueitls that no apprecial»le change in growth rate or yield will result from the inlroduclion of additional amounts in the range ordinarily expected to be present in tnaterials to be assayed. As a point of referetice for this work some of the culture media in mc)st common current use will he cotisidered briefly. For ease of comparis4)n Iheir mineral compositions are listed in Tables 1 and 2. White's nutrient .solution, designed originally for excised root cultures, was based on Uspeuski and Uspetiskaia's medium for algae and Trelease and Trelease's micronutrieni solution. This medium also was employed successfully in the original cttltivation of callus from the tobacco Iiybrid Nicotiana gtauca x A', tanijadorffii, atitl as further modified by White in 194̂ ^ and by others it has been used for the

On the Inhibition of Bud Development and other Functions of Growth Substance in Vicia Faba

Abstract: It is well known that when the growing point of a young dicotyledonons plant is removed, the axillary buds lower down the stem grow out strongly, and eventually take the place of main stem. The presence of the terminal bud thus exercises an inhibiting action on the development of the lateral buds, causing them to remain dormant. To a smaller extent the leaves also inhibit the development of buds in their axils, as was shown by Dorsal (1909). The phenomenon has been studied by many workers, among others by Snow, who found (1929, a ) that the rapidly growing young leaves in the terminal bud were the most active in inhibiting development of the axilllaries. It appears also, from our experiments, that the rapid growth of a lateral bud is accompanied by inhibition of the bud immediately below it, and a similar behaviour of opposite buds was observed by Dorsal (1926). In a brief preliminary communication (Thimann and Skoog, 1933) it was shown that the inhibiting action of the terminal bud can be imitated by applying the growth substance ("auxin" or "Wuchsstoff") to decapitated plants. These experiments, and others, will now be described more fully; further, the relation between the growth promoting action of growth substance and its effect on bud inhibition will be considered. The first evidence that the inhibition of lateral bud development might be caused by a special substance was brought forward by Snow (1929, b ). The work to be described here proves that inhibition can be caused in this way, and shows that the inhibiting substance is almost certainly identical with the hgrowth substance. Literature on the growth substance need not be discussed here (see Nielsen, 1930; du Buy and Nuernbergk, 1932; Thimann and Bonner , 1933); it is only necessary to mention that the substance promotes growth by cell elongation and not by cell division. On this account it has been principally studied in the Avena coleoptile, in which it is produced in the tip and transported in a polar manner towards the base.

A revised medium for rapid growth and bio assays with tobacco tissue cultures

Abstract: In experiments with tobacco tissue cultured on White's modified medium (basal meditmi hi Tnhles 1 and 2) supplemenk'd with kiticthi and hidoleacctic acid, a slrikin^' fourlo (ive-told intTease iu yield was ohtaitu-d within a three to Tour week j^rowth period on addition of an aqtteotis exlrarl of tobacco leaves (Fi^'ures 1 and 2). Subse(iueutly it was found Ihiit this jnoniotiou oi' f^rowih was due mainly though nol entirely to inorj^auic rather than organic con.stitttenls in the extract. In the isolation of Rrowth factors from plant tissues and other sources inorj '̂anic salts are fre(|uently carried along with fhe organic fraclioits. When tissue cultures are used for bioassays, therefore, il is necessary lo lake into account increases in growth which may result from nutrient elements or other known constituents of the medium which may he present in the te.st materials. To minimize interference trom rontaminaitis of this type, an altempt has heen made to de\\eh)p a nieditmi with such adequate supplies of all re(iuired tnineral nutrients and cotntnott orgattic cottslitueitls that no apprecial»le change in growth rate or yield will result from the inlroduclion of additional amounts in the range ordinarily expected to be present in tnaterials to be assayed. As a point of referetice for this work some of the culture media in mc)st common current use will he cotisidered briefly. For ease of comparis4)n Iheir mineral compositions are listed in Tables 1 and 2. White's nutrient .solution, designed originally for excised root cultures, was based on Uspeuski and Uspetiskaia's medium for algae and Trelease and Trelease's micronutrieni solution. This medium also was employed successfully in the original cttltivation of callus from the tobacco Iiybrid Nicotiana gtauca x A', tanijadorffii, atitl as further modified by White in 194̂ ^ and by others it has been used for the

Nutrient requirements of suspension cultures of soybean root cells.

Abstract: The nutrient requirements of suspension cultures from soybean root have been investigated, and a simple medium consisting of mineral salts, sucrose, vitamins and 2,4-dichlorophenoxyacetic acid (2,4- d ) has been designed. The cells required thiamine, 2,4- d and ammonium in addition to the usual mineral salts and sucrose. Optimum concentrations of nitrate and ammonium were 25 and 2 m M respectively. The highest yield of cells was achieved at an initial pH of 4.5–5.5. During the growth cycle the pH gradually increased to 6.0–6.2.

Generic assignments, strain histories, and properties of pure cultures of cyanobacteria

Abstract: Summary: On the basis of a comparative study of 178 strains of cyanobacteria, representative of this group of prokaryotes, revised definitions of many genera are proposed. Revisions are designed to permit the generic identification of cultures, often difficult through use of the field-based system of phycological classification. The differential characters proposed are both constant and readily determinable in cultured material. The 22 genera recognized are placed in five sections, each distinguished by a particular pattern of structure and development. Generic descriptions are accompanied by strain histories, brief accounts of strain properties, and illustrations; one or more reference strains are proposed for each genus. The collection on which this analysis was based has been deposited in the American Type Culture Collection, where strains will be listed under the generic designations proposed here.

Efficient transformation of rice (Oryza sativa L.) mediated by Agrobacterium and sequence analysis of the boundaries of the T-DNA.

Abstract: Summary A large number of morphologically normal, fertile, transgenic rice plants were obtained by co-cultivation of rice tissues with Agrobacterium tumefaciens The efficiency of transformation was similar to that obtained by the methods used routinely for transformation of dicotyledons with the bacterium Stable integration, expression and inheritance of transgenes were demonstrated by molecular and genetic analysis of transformants in the R0, R1 and R2 generations Sequence analysis revealed that the boundaries of the T-DNA in transgenic rice plants were essentially identical to those in transgenic dicotyledons Calli induced from scutella were very good starting materials A strain of A tumefaciens that carried a so-called ‘super-binary’ vector gave especially high frequencies of transformation of various cultivars of japonica rice that included Koshihikari, which normally shows poor responses in tissue culture