摘要:

A synthetic medium for vegetative growth and apothecial formation of 2 compatible strains ofA immersushas been formulated as follows: KH2PO4, 0.5 g; K2HPO4, 0.6 g; MgSO4·7H2O, 0.5 g; micronutrients, 0.1 ml (Vogel's); asparagine, 5 g (for vegetative growth), or urea, 1 g (for apothecial formation); dextrin (Merck), 20 g; biotin, 5 μg; thiamine, 100 μg; and distilled water, 1 liter. This medium had a pH of 6.2 to 6.7 without adjustment and was satisfactory. For apothecial formation, 20 g Noble agar (Difco) and 2 g cellulose powder (Whatman) were added to the above medium. Apothecial formation was better at 23–24 than at 25–26 C. Light was necessary for apothecial formation. Dextrin, soluble starch, glucose and mannose were satisfactory carbon sources for both vegetative growth and apothecial formation. This fungus could not use lactose, sucrose, sorbose, mannitol, sorbitol or insulin as carbon sources. It could assimilate nitrate in the form of KNO3. Optimum yields were obtained with asparagine, aspartic acid, or glutamic acid as the source of nitrogen. The optimum nitrogen‐carbon ratio for apothecial formation was about 2% dextrin and 0.1% urea. This ratio was given the highest apothecial rating 10.Ascobolus immersuswas deficient in the ability to synthesize biotin and thiamine.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06625.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The origin of morphological differences attributable to mutant genes can be identified at certain switch points in the developmental pathway. The effect of thePolytypic (Pt)gene is a stimulus to meristems in the developing inflorescence to continuous initiation of differentiating structures. The most severe expression is a suppression of meristematic activity. The action of the gene is a superimposition of its effect on the normal developmental pathway. Theramosa‐1 (ra1) gene interrupts the normal sequence of events, at the switch point, which would normally result in spikelet formation, and there is produced instead a lateral branch. The response of numerous switch points in the developmental pathway of the maize inflorescence supports the conclusion that meristems are a plastic system genetically programmed at successive intervals.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06626.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

A mutant of strain 69–1113a ofNeurospora crassa,which shows periodic growth upon both complete and minimal media, was named “clock,” and some of the morphological and genetic differences between this mutant and the “patch” and “wild” strains were investigated. In contrast to the uniform growth of “wild,” the “clock” mutant produces a series of bands formed by cymelike aggregations of hyphae which become progressively more dense and finally mark the end (front) of a growth band. A new growth band is formed by a number of hyphae which grow out as in “wild” strains and dichotomize and form new cymes which again become progressively more dense and finally form a new front. It is shown that “clock” continues its rhythmic growth when cultured in continuous darkness. Some “wild” strains were induced to grow periodically on appropriate media. A medium containing equal quantities of sorbose and sucrose caused strain 65–811A (a “wild”) to produce the “patch” type growth. Random isolation, as well as ordered isolation, of ascospores following a cross between “wild” and “clock” show a 1: 1 segregation indicating that “clock” differs from “wild” by a single gene.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06627.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

In contrast to the odd‐pinnately compound leaf of the normal (+/+) tomato plant(Lycopersicon esculentum), the single‐gene mutantlanceolate (La/+) generally has a simple leaf.Lanceolateplants, also, have small fruits and flowers, weak apical dominance, and exhibit variation in the position and fusion of cotyledons. Homozygous mutants(La/La)appear in 3 different phenotypes, 1 of which,narrow,has narrow simple leaves, sterile inflorescences, and extremely weak apical dominance. The other 2,modified,andreduced,lack an organized shoot. After selfingLa/ +plants for 9 generations, autotetraploids were produced with the aid of colchicine. In addition, several triploid plants arose spontaneously. The study of diploid, triploid, and tetraploid material with various proportions of theLaallele revealed in many characters a graded series as a function of theLadosage. With increasingLadose, there was a gradual reduction in: (1) total leaf length; (2) the number and size of primary and secondary lateral leaflets; (3) the number and size of marginal lobes of the terminal leaflet, associated with an increase in the proportional length of the terminal leaflet. Many leaves were found with the basal lobes of the terminal leaflet resembling incompletely separated lateral leaflets. The differences in leaf shape between different genotypes came about before the leaf primordium was 3 mm long. There was a progressive delay in the initiation of lateral primordia with increasingLadosage. It is proposed that the gradual changes from compound to simple leaves with increasingLadosage are produced by successively greater restrictions of meristematic activity after the terminal leaflet is formed. With increasing proportion ofLaalleles, the reproductive structures showed: (1) a decrease in the number of flowers per inflorescence; (2) a decrease in the length of the sepals; (3) an increase in the proportion of flowers with dialytic anthers. Dialytic anthers had narrow adaxial lobes and were frequently twisted along their main axes. The common denominator for most trends affected by theLaallele seems to be a general reduction of growth, but more so in lateral than in longitudinal growth. Histological data suggest that the reduction in lateral growth is mainly brought about by a reduction of cell division in lateral meristems.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06628.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

When grown in vitro in a medium containing NH4NO3as the sole source of nitrogen, seeds ro the orchid,Cattleya (C. labiata‘Wonder’ XC. labiata‘Treasure'), germinated readily and proceeded to form small plantlets. Development of the embryos was accompanied by an increase in their total nitrogen and a decline in the percent dry weight. Growth responses of the seedlings in other ammonium salts like (NH4)2SO4, (NH4)2HPO4, NH4Cl, ammonium acetate and ammonium oxalate were similar to that in NH4NO3. However, when grown in a medium containing NaNO3, development of the seedlings was drastically inhibited; KNO3, Ca(NO3)2, KNO2and NaNO2also were poor nitrogen sources. Attempts to grow the seedlings in NaNO3by changing the pH or by addition of kinetin, molybdenum or ascorbic acid as supplements were completely unsuccessful. When seedlings growing in NH4NO3for varying periods were transferred to NaNO3, it was found that those plants allowed to grow for 60 or more days in NH4NO3could resume normal growth thereafter in NaNO3. Determination of the nitrate reductase activity in seedlings of different ages grown in NaNO3, after NH4NO3, showed that the ability of the seedlings to assimilate inorganic nitrogen was paralleled by the appearance of the enzyme.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06629.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Cultures of callus tissue derived from roots, petioles, or umbellet peduncles of the wild carrot have been observed to form large numbers of adventive embryos which closely resemble ovular embryos of the same species. In the presence of cocoanut milk, which is not otherwise required in the nutrient medium, these embryos germinate and produce plants which may be normal in all respects. The sequence of forms in embryogenesis has been traced back to embryos of fewer than 10 cells, and the pattern of development has been found in many cases to correspond closely to that of ovular embryos, especially with respect to the early filamentous stages. The accumulation of granular starch in both the parenchymatous cells of the callus and in the embryos at certain stages of their development is a marked characteristic of differentiating callus. Investigation of the nutrient requirements of the callus tissue undergoing differentiation of embryos reveals that a wide latitude is possible in the composition of the basal medium, consisting of mineral salts, vitamins, and sucrose. Embryos form readily in tissue which has been extensively subcultured on a simple defined medium which consists of the basal medium plus adenine and 2,4‐D. Tissues cultured on cocoanut milk and 2,4‐D, or kinetin and 2,4‐D, are more heterogeneous in composition and may contain, in addition to embryos, idioblastic tracheids, anthocyanin‐pigmented cells, and complex vascularized nodules. Chemical control of alternative morphogenetic pathways, and of embryogenesis itself, is partially demonstrable.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06630.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Two clones of tissue of single‐cell origin isolated from crown gall callus ofNicotiana tabacumwere examined cytologically. Both clones had been grown on the same medium under the same conditions for 8 years. Chromosome counts of 110 polar views of metaphase plates revealed chromosome numbers of 48, 96, and 192 in both clones, the majority having 48. The nucleus of the original cell from which each clone was grown must have possessed 48 chromosomes. The polyploidy which developed may be ascribed to wounding, to the constituents of the culture medium, and/or to abnormal mitoses.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06631.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The potential for the production of abundant conidia was suggested when an essentially non‐conidial isolate ofAspergillus rugulosus,obtained from dune sand, was grown at 25 C rather than at the usual 37 C. Ultraviolet‐light‐induced conidial strains were obtained from the original non‐conidial isolate. Evidence is presented which suggests that the production of conidia is under the control of a single nuclear gene. The data, with a single exception, suggest that induced conidial mutations represent alterations at the same locus. Crosses with isolates from various localities indicate that the genes controlling conidiation in these strains may be linked to or independent of the genes studied in the original dune‐sand isolate. No evidence has been obtained which would suggest involvement of a diffusible substance in the control of conidiation.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06632.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

Experiments concerning the effects of benzyladenine applications on the growth and senescence of leaves have been carried out with cuttings of bean seedlings. By measuring the interactions between leaves, it was found that this kinin not only can stimulate the growth of a treated whole leaf, but it can bring about the inhibition of growth in other untreated leaves on the same plant. Consistent, with the apparent mobilizing actions of this chemical, it was found that applications to one or more leaves would induce the senescence of untreated leaves in a manner similar to the senescence‐inducing effects of stem apices and flowers and fruits. The experiments suggest that the mobilization effects due to natural kinins in such centers in the intact plant may provide endogenous stimuli of leaf senescence.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06633.x

出版商:Wiley    

年代:1964

数据来源: WILEY

摘要:

The seedlings ofPisum sativumvar. ‘Alaska’ grown either in complete darkness or in partial red light are often afflicted by a plasmodial parasite, which either partially or completely destroys the tracheids. The vegetative stage of the organism consists of small cells connected with each other by hyaline filaments. These cells are seen inside the tracheids, where they presumably hydrolyze cellulose to separate the lignified helical wall thickenings from the cell wall. The spirals are then incorporated into a plasmodium. The plasmodia are found both inside and outside the plant tissue. The younger portions of the seedlings often contain large plasmodia with engulfed helical wall thickenings, which are gradually dissolved, presumably by means of a peetinolytic enzyme, at the time of sporulation. The spores (4–5μ) are borne in small numbers, ca. 10–16 per well‐defined oval or elongate sporangium. The pitted vessels are not destroyed by the organism. Pea seedlings can be badly infected without showing externally visible pathology. Unless the xylem is destroyed and the plant tissues are filled with plasmodia, recovery from the infection is possible.Pisum sativum,a homozygous variety ‘L’ grown aseptically in light on an agar medium, also contained all the stages in the development of this organism.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1964.tb06634.x

出版商:Wiley    

年代:1964

数据来源: WILEY