摘要:

Towner, JosephW. (U. California, Los Angeles.)Cytogenetic studies on the origin of Tagetes patula. I. Meiosis and morphology of diploid and allotetraploid T. erecta × T. tenuifolia.Amer. Jour. Bot. 48 (9): 743–751. Illus. 1961.—Cytological and morphological evidence is presented to show thatTagetes patulaL. is an allotetraploid species (2n= 48) which probably originated by hybridization between the diploidsT. erectaL. andT. tenuifoliaCav., or species closely related to them. The putative parent species are separated by strong reproductive isolation barriers, and controlled crosses between them yielded very few good seed. Most of the hybrid seedlings died before reproductive age, and the few survivors were sterile and extremely weak. At meiosis in the diploid hybrid, bivalent frequency per cell was 0–11 and averaged 4.4. Although 43.6% of the quartet stage consisted of restitution dyads, pollen was essentially all non‐viable and seed set was less than 1%. A true‐breeding, fertile, allotetraploidT. erecta‐tenuifoliawas synthesized by colchicine‐doubling of the chromosome number of the F1hybrid. In the synthetic allotetraploid, average chromosomal association was 23.97 bivalents plus 0.05 univalents, and 97.4% of MI cells had 24 bivalents; there were no multivalents, bridges, or fragments.Tagetes erecta‐tenuifoliashowed a striking morphological similarity toT. patula.Both the natural and synthetic allotetraploids were intermediate betweenT. erectaandT. tenuifoliafor nearly every character. Of 10 species ofTageteswhose chromosome numbers are known, 5 are tetraploid (2n= 48).

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11706.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Raghavan, V., and W. P. Jacobs. (Princeton U., Princeton, N. J.)Studies on the floral histogenesis and physiology of Perilla. II. Floral induction in cultured apical buds of P. frutescens.Amer. Jour. Bot. 48(9): 751–760. Illus. 1961.—The morphological and histological changes induced in apical buds and explants ofP. frutescens(L.) Britt. var. ‘Tall Late’ in short days and long days when cultured in White's medium have been followed. When photoinduced in culture, apical buds showed visible signs of changes in 30.9 days, and produced normal flowers in 81.6 days. Apical buds in LD showed similar transformations at the apices, but with continued LD treatment, they elongated to form sterile structures, superficially resemblingSelaginellacones. The normal flowers formed in culture were similar to those formed on the intact plant, while the individual florets of the LD‐cone differentiated only the non‐sporogenous tissues in them. A less pronounced sequence of changes resulted when apical buds stripped of their older pairs of apical leaves were LD‐ or SD‐treated. When explants with the 1st pair of unfolded leaves or with the 1st and 2nd pairs of unfolded leaves were photoinduced in vitro, the responses were relatively fast. However, explants with the 1st and 2nd pairs of unfolded leaves in LD remained entirely vegetative. When unfolded leaves were implanted in the same medium separated from the buds and both were photoinduced or given LD, the buds formed the typical 1st signs, but did not differentiate into normal flowers. This inhibition of flowering resulted in the formation of sterile cones, consisting of florets with non‐sporogenous tissues only. The results have suggested the possibility of the sterile cone‐like structures being an intermediate stage in the flowering ofPerilla.The role of a possible inhibitor produced by mature leaves of SD plants in LD is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11707.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Shatkin, A. J., and E. L. Tatum. (The Rockefeller Institute, New York 21, New York.) The relationship of m‐inositol to morphology in Neurospora crassa. Amer. Jour. Bot. 48(9): 760–771. Illus. 1961.—The role of m‐inositol and its relationship to morphology inNeurospora crassahave been examined. The growth pattern of the inositolless mutant has been found to be a function of concentration of carbon and nitrogen sources and m‐inositol, utilizability of carbon source, ratio of concentrations of sugar to m‐inositol, and size of conidial inoculum. Inhibition of mycelial m‐inositol uptake has been demonstrated for a number of carbon sources, and the ability of a particular compound to inhibit m‐inositol uptake found to be directly related to both its effectiveness as an energy source and its effect on the morphology of the inositol‐requirer. Results of cell‐fractionation experiments and autoradiography have shown that phospholipid inositol is widely distributed in the hyphae and not bound in a single subcellular organelle. Electron micrographs of cell fractions indicate that inositol is a structural constituent ofN. crassalipoprotein membranes, including plasmalemma, nuclear envelope, mitchondrial membranes, and endoplasmic reticulum. Normal inositol‐requiring and wild‐type hyphae are similar in ultrastructure. However, sub‐optimally cultured, colonial, inositolless hyphae contain large lipid droplets, and the cellular membranes are in various stages of degeneration. Chemical evidence indicates that colonial hyphae do not synthesize more fat than normal hyphae, suggesting that the lipid droplets are products of membrane catabolism. It is proposed that the colonial morphology of the inositol‐requiring mutant ofN. crassais due to a metabolic imbalance between membrane synthesis and the synthesis of other cellular constituents.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11708.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Nath, J., and E. L. Nielsen. (U. Wisconsin, Madison.)Cytology of plants from self‐ and open‐pollination of Phleum pratense.Amer. Jour. Bot. 48(9): 772–777. Illus. 1961.—Conventional cytological disturbances and several anomalous behaviors such as heavy‐walled coenocytes, uncoiled chromosomes, supernumerary chromosomes, production of cross‐bridges at second division, and the occurrence of globular structures in the microsporocytes were associated with sterility in timothy. These anomalies have not been described previously as contributory to reduced seed set in timothy.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11709.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

McMillan, Calvin. (U. Texas, Austin.)Nature of the plant community. VI. Texas grassland communities under transplanted conditions.Amer. Jour. Bot. 48(9): 778–785. Illus. 1961.—Clones of 7 grass taxa,Bouteloua gracilis(H. B. K.) Lag.,B. eriopoda(Torr.) Torr.,B. curtipendula(Michx.) Torr.,Panicum virgatumL., theAndropogon scopariusMichx. complex, theAndropogon gerardiVitman‐halliiHack. complex, andSorghastrum nutans(L.) Nash, were transplanted from throughout their distribution in Texas and studied in an experimental garden at Austin. Restricted to western Texas and Panhandle areas,Bouteloua gracilisandB. eriopodacontained similar early‐flowering clones throughout their distribution. Less restricted to western sites,B. curtipendulacontained later‐flowering types from eastern and central areas. In the 4 remaining, widespread taxa, early‐flowering potential characterized clones from western sites. These 4 widespread taxa contain the latest‐flowering clones from the coast of southern Texas. Clones ofStipa leucotrichaTrin. and Rupr. from a broad area in Texas lacked a flowering gradient. Grassland communities of western Texas and the Panhandle, attuned to short growing seasons and low rainfall, were composed of opportunists, theBoutelouaspecies, and early‐flowering variants within the widespread species. Communities of central Texas in habitats of highly unpredictable moisture pattern and a relatively long growing season contained later‐flowering variants. Coastal communities attuned to a long growing season contained the latest‐flowering variants.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11710.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Koch, WilliamJ. (U. North Carolina, Chapel Hill.)Studies of the motile cells of chytrids, III. Major types.Amer. Jour. Bot. 48(9): 786–788. Illus. 1961.—Six major types of chytrid motile cells are recognized on the basis of the internal parts present and their appearances and arrangements. Eighteen species are placed in these 6 types.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11711.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Garrison, Rhoda(Wheaton Coll., Norton, Mass.), and RalphH. Wetmore.Studies in shoot‐tip abortion: Syringa vulgaris.Amer. Jour. Bot. 48(9): 789–795. Illus. 1961.—The growth of shoots ofSyringa vulgarisis described with special reference to the sequence of events in the abortion of the tip. Early in the growing season, as the shoot begins to elongate, the terminal part, 4–7 mm in length and bearing 3 or 4 pairs of young leaves, ceases growth; then after 2 or 3 wk in which there is no change in form, the tip becomes yellow and disintegrates. Diffusible auxin is present in the terminal region as a shoot begins to elongate, but after the abortive phase is initiated, auxin can no longer be detected in that part. Young shoots and tips of shoots when cultured in nutrient media ultimately abort in the normal manner. Shoot tips in the early stages of abortion can be stimulated to resume growth and development if the axillary buds just subjacent to the tip are destroyed; this response is, however, limited to vigorously growing shoots.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11712.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

O'Kelley, JosephC., and WalterR. Herndon. (U. Alabama, University.)Alkaline earth elements and zoospore release and development in Protosiphon botryoides. Amer. Jour. Bot. 48(9): 796–802. Illus. 1961.—Cells ofProtosiphon botryoidesKlebs from depleted nutrient medium containing Ca were washed and resuspended in fresh complete medium with Ca; or in media with a Sr, Ba or Na replacement, respectively, for Ca; or in an equivalent CaCl2solution or deionized water. Zoospore release was observed in these media upon illumination following a 12‐hr dark period. Free zoospores were less abundant in Sr‐, Ba‐ and Na‐replacement media than in the Ca medium. Zoospore production and release also were depressed in solutions of only CaCl2and in deionized water. In the Sr and Ba media, zoospores were formed but not released from the parent cell, as a rule; some zoospores were released in mass within a gelatinous vesicle which did not liquefy and set the zoospores free; these zoospores lost motility and continued development in Sr, producing characteristic, spheroidal clusters of aplanospores. In the Na medium, protoplasmic cleavage preceding zoospore formation was severely inhibited. A study of the reversibility of Sr inhibition of the zoospore‐release mechanism revealed evidence of reversion 12 hr after replacement of Sr by Ca. Walls of cells produced in Ca are rich in ruthenium red‐positive materials, whereas cells produced under conditions of Sr replacement lack these materials. The significance of these findings in relation to the Ca requirement of other algal species is discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11713.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Hall, MarionTrufant. (Butler U., Indianapolis, Ind.)Teratology in Trillium grandiflorum.Amer. Jour. Bot. 48(9): 803–811. Illus. 1961.—Attempts were made to determine the causes of persistent but seasonally variable abnormalities in both vegetative and floral organs of an assemblage of plants grouped under the nameTrillium grandiflorumvar.variegatumSmith. Comparative studies of vegetative and floral morphology between normal and abnormal plants are presented and illustrated. Normal shoots of the same rhizome vary but little from season to season. Abnormal shoots of the same rhizome vary markedly in some instances and very little in others from season to season. In the abnormal shoots, leaves and petals vary most, then stamens, ovaries, and sepals, in that order. In the populations observed, abnormal plants did not mature seed even though only a few specimens were seen which had no viable pollen. A comparative study of leaf and flower proteins of normal (var.grandiflorum) and abnormal (var.variegatum) plants was made. Electrophoretic analysis showed no virus but showed leaf protein abundant in the floral organs, particularly in the petals. It is suggested that the presence of these extra leaf proteins is sufficient to increase variability in the floral organs and in most cases to prevent the normal development of the sporophylls.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11714.x

出版商:Wiley    

年代:1961

数据来源: WILEY

摘要:

Melchior, RobertC., and JohnW. Hall. (U. Minnesota, Minneapolis.)A calamitean shoot apex from the Pennsylvanian of Iowa.Amer. Jour. Bot. 48(9): 811–815. Illus. 1961.—A shoot apex of a calamitean stem is described from the Des Moines Series, Middle Pennsylvanian. Internodal elongation of the 7 preserved internodes follows a sigmoid curve. A large apical cell has produced derivatives in a fashion apparently comparable to those inEquisetum arvense, except for the number of cells in the first leaf primordium ring and, possibly, the intercalary meristem. Pith meristem developed close to the apical cell. Data from internodal cell elongation of hypodermal cells of the cortex are presented which demonstrate intercalary internodal growth; no intercalary meristems are preserved and the existence of intercalary meristems which might have produced a jointed stem like that ofEquisetumis only inferred.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1961.tb11715.x

出版商:Wiley    

年代:1961

数据来源: WILEY