摘要:

Matchett, WilliamH., and J. F. Nance. (U. Illinois, Urbana.)Cell wall breakdown and growth in pea seedling stems.Amer. Jour. Bot. 49(4): 311–319. Illus. 1962.—Carbon‐14 introduced into cell‐wall constituents of pea stems is subject to metabolic turnover. Turnover is increased when test tissues are supplied with growth‐promoting levels of indoleacetic acid and decreased by growth‐inhibiting levels of mannitol and galactose. Studies on uptake of calcium‐45 confirm earlier work by showing that treatment of pea‐stem slices with growth‐promoting levels of indoleacetic acid results in an increased capacity for rapid uptake of calcium ion. Studies on loss of calcium‐45 by previously labeled pea‐stem slices confirm earlier observations by showing that this loss is greatly enhanced by the presence of indoleacetic acid. Experiments designed to test the effects of various exchangeably bound ions upon the extent of carbon‐14 turnover reveal that turnover is increased by the presence of potassium ion or magnesium ion and that in each case calcium ion reverses the effect. Studies on the tip‐burst response exhibited by growing pollen tubes reveal that either anaerobiosis or the presence of potassium ion increases the frequency of bursting. The results of this investigation are discussed with reference to several hypotheses concerning plasticization of the primary cell wall.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14943.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

McClendon, JohnH. (U. Delaware, Newark.)The relationship between the thickness of deciduous leaves and their maximum photosynthetie rate.Amer. Jour. Bot. 49(4): 320–322. Illus. 1962.—Data of Willstätter and Stoll (25°, saturating light and CO2) are used to show that it is useful to plot photosynthetie rate per unit area as a function of the density thickness (g/cm2; fresh wt) of the leaves. Data for 23 species were plotted together. If P is photosynthetie rate, T the total density thickness, E the density thickness of the epidermis, a linear relation is found using themaximumvalues of P, such that P = R (T ‐ E), where R is about 30 (mg CO2) (hr)‐1(g F.W.)‐1. Using this expression, 15 species were represented by values of R over 23, while very young leaves, aurea2leaves and a few others fell in the range 8–16. A mean value of E was taken, from other data, to be about 3 × 10‐3g/cm2, while T ranged from 10 to 40 × 10‐3g/cm2, and P ranged from 0.2 to 0.8 (mg CO2) hr‐1cm‐2for “normal” leaves.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14944.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Klein, RichardM., EmeritaM. Caputo, and BarbaraA. Witterholt. (New York Bot. Gard., N. Y., N. Y.) The role of zinc in the growth of plant tissue cultures. Amer, Jour. Bot. 49(4): 323–327. Illus. 1962.—Zinc‐sufficient and zinc‐deficient auxin‐auxotrophic callus and auxin‐prototrophic crown‐gall cultures ofParthenocissus tricuspidatuswere examined for their growth capacity and ability to synthesize tryptophan. Growth capacity decreased rapidly when zinc ion was withheld and tryptophan synthetase activity in vitro was reduced. Growth of –Zn crown‐gall tissues was stimulated by either auxin or tryptophan and growth of –Zn callus cultures was stimulated by tryptophan.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14945.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Berlyn, GraemeP. (Yale U., New Haven, Conn.)Developmental patterns in pine polyembryony.Amer. Jour. Bot. 49(4): 327–333. Illus. 1962.—An investigation of multiple‐embryo development in pine was undertaken. The occurrence of 4 embryos per mature seed was found in approximately one third of the seeds ofPinus lambertianaandPinus cembraexamined and in a few seeds ofPinus strobus.These embryos were derivatives of the 4 embryo‐initial cells of the apical tier of the proembryo. There was a progressive reduction in size and development of embryos in a given seed, the embryo furthest from the micropyle being the largest and most differentiated. However, in many cases, histogenesis proceed even when embryo size was significantly arrested. All 4 embryos in some seeds were viable in vitro, but rarely did more than one embryo germinate in vivo. This may be associated with the more rapid reactivation of the largest embryo. Variation in the extent of multiple‐embryo development reflects the apparently indeterminate pattern of competition within an embryo system.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14946.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Nanda, K. K. (Forest Res. Inst., Dehra Dun, India.)The emergence and development of branches in Crotalaria juncea and their relationship to flowering.Amer. Jour. Bot. 49(4): 334–341. Illus. 1962.—Seeds ofCrotalaria junceaL. were sown in pots on March 23, 1959, and records were kept of the dates of emergence of individual branches and the appearance of flower buds on them. Periodical observations were also made of the height of the main shoot as well as its branches and the number of nodes and leaves borne by them throughout the year. The main shoot elongates rapidly and terminates in an inflorescence. Development of lateral buds remains completely arrested during the period of rapid elongation and is initiated only after the appearance of the floral buds when it takes place in basipetal sequence. The flowering of the branches also takes place in a basipetal manner. This mode of emergence of branches and their flowering are exhibited even by secondary and tertiary branches. The length attained by these branches is very small as the flower buds appear soon after their emergence. In contrast, the branches formed towards the middle of May continue to elongate for a considerable period and become many times longer than the main shoot or the branches produced earlier in the season. The vegetative period of these branches is also very much prolonged. These differences in the height attained by branches produced at different times of the year and the basipetal sequence in the emergence of branches and their flowering appear to be under the control of some physio‐chemical changes which cause the transformation of the growing apex from the vegetative to the reproductive state. This holds good irrespective of whether these changes are brought about as a result of a favorable environmental complex, as is the case with the main shoot and late‐formed, much elongated branches, or are due to the favorable internal conditions produced within the plant as a result of the completion of the developmental process of the main shoot, as happens in the case of branches produced earlier in the season.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14947.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Zenkteler, Maciej. (U. Adam Mickiewicz, ul. Stalingradzka 14, Poznan, Poland.)Microsporogenesis and tapetal development in normal and male‐sterile carrots (Daucus carota).Amer. Jour. Bot. 49(4): 341–348. Illus. 1962.—Meiosis and anther development proceed normally in fertile plants. Nine pairs of chromosomes are present at diakinesis and at metaphase I. The mature pollen grains possess 2 male gametes at the time of shedding; 80–92% of the pollen appears normal. A cross‐shaped configuration at pachytene characteristic of a reciprocal translocation is present in the completely pollen‐sterile plants indicating that one of the parents is homozygous for an interchange between 2 members of the chromosome complex. Chromosome bridges with fragments at anaphase I and anaphase II lead to aberrant chromosome distribution during meiosis. Complete microspore abortion is associated with a periplasmodium formation of the tapetum and anther wall deterioration.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14948.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Shaver, DonaldL. (Brookhaven Natl. Lab., Upton, New York.)Cytogenetic studies of allotetraploid hybrids of maize and perennial teosinte.Amer. Jour. Bot. 49(4): 348–354. Illus. 1962.—Euchlaena perennis(4n), “perennial teosinte,” was less fertile when pollinated with 4n Zea maysthan when selfed. Cross fertility between the 2 genera was influenced by the particular maize stock involved. Chromosome numbers varied from 36 to 43 in a population of 4nmaize maintained by interpollination without regard to chromosome number. In the 4nintergeneric hybrid, nearly every chromosome number from 29 to 44 was found. The expression of the perennial growth habit varied with the proportion of perennial teosinte germ plasm present. Triploid hybrids with 2 perennial teosinte genomes and 1 maize genome were usually perennial. Tetraploid hybrids having 2 genomes of each parent were usually not fully perennial. Tetraploid hybrids with only 1 perennial teosinte genome had no perennial tendency but had a strong tendency to tiller. As compared with autotetraploids of maize having the same genetic markers, intergeneric hybrids showed a highly significant degree of preferential segregation for each of the 12 marker genes studied. In the opinion of the author, these data may represent the best available measure of the relationship of maize to teosinte, and are considered to support the proposal of Reeves and Mangelsdorf that maize and teosinte are congeneric.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14949.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Wheeler, GeorgeE. (Brooklyn Coll., Brooklyn, New York.)Polygonal aspects of cell faces. II. Quadrilaterals as the prevailing type.Amer. Jour. Bot. 49(4): 355–362. Illus. 1962.—Quadrilateral faces are abundant and even predominant among the faces of certain types of cells. Data taken from the literature and several original samples were studied to define the conditions which foster large numbers of quadrilaterals. The presence of free faces (cells on air spaces) profoundly affects cell‐face distributions. There is a great excess of quadrilaterals on cells with 2 free faces on opposite sides (cells of single layers). Among cells with 1 free face (cells of epidermises), pentagonal faces usually surpass quadrilateral faces, although they are just about equal in a few samples. Intermediate ratios of the 2 face types occur in samples which include cells having faces touching 1 free face, mixed with cells having faces between 2 free faces. The “competition” for numerical superiority shifts to pentagons vs. hexagons, among cells comprising internal tissues (cells in contact on all sides with other cells). With respect to epidermises, the relative size of epidermal and of subepidermal cells strongly influences the relative numbers of quadrilaterals and pentagons. A marked trend toward quadrilaterals may also be found in connection with a quite different set of cell relationships: if 2 layers of elongated cells occur together, and if their long axes are mutually perpendicular, then a “checkerboard” pattern may result. This arrangement favors large numbers of quadrilateral faces; in some samples, they may even dominate. It is suggested that certain modifications of this pattern may generate large numbers of triangular and of lenticular (lens‐shaped) faces. Varying patterns of cell division are considered to be primarily responsible for changes in cell‐face distributions and for changes in predominating face types.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14950.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Stern, KingsleyR. (Chico State Coll., Chico, Calif.)The use of pollen morphology in the taxonomy of Dicentra.Amer. Jour. Bot. 49(4): 362–368. Illus. 1962.—The pollen morphology ofDicentrahas proved to be of great interest because of interspecific differences in surface character istics of pollen grains in all but 2 instances within the genus. Descriptions of the pollen of the 19 species and a key based on pollen morphology are given. Correlations between pollen morphology and gross morphology and anatomy are discussed, and phylogenetic trends are indicated.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14951.x

出版商:Wiley    

年代:1962

数据来源: WILEY

摘要:

Arya, H. C., A. C. Hildebrandt, and A. J. Riker. (University of Wisconsin, Madison, Wisconsin.)Clonal variation of grape‐stem and Phylloxera‐gall callus growing in vitro in different concentrations of sugars.Amer. Jour. Bot. 49(4): 368–372. Illus. 1962.—The original callus grown from normal tissue and that grown from gall tissue contained mixtures of different kinds of cells. To study the variability, a large number of clones were developed by single‐cell technique. From these, 6 clones were selected for detailed study. Growth was compared of 6 single‐cell clones established in vitro; 3 from normal grape stem and 3 from gall tissues incited byPhylloxera vastatrixPlanch. The clones were stable in growth rate (fast, medium, and slow) when grown on modified White's basal medium supplemented with coconut milk, α‐naphthaleneacetic acid (NAA), and calcium pantothenate. Growth was measured after 6 weeks as the average wet weight on concentrations from 0.06–4.0% of sucrose, d(+) dextrose, d(‐) levulose, d(+) mannose, d(+) galactose, and d(+) lactose, respectively. Every sugar, except mannose, was a suitable source of carbon. The cells were not all alike in their growth response to different sugars. Gall‐ and normal‐tissue clones grew best with 0.125% sucrose, levulose, and galactose. With dextrose and lactose, optimum yields were obtained at the 1.0% sugar level. Growth of fast‐, medium‐, and slow‐growing clones was altered with the type of sugar. Gall and normal tissues were differentiated from each other when grown on mannose in which gall tissues grew best at 0.125% and normal at 1.0% levels. Gall tissues as a group were able to grow better with mannose than the corresponding normal ones. Levulose, on the other hand, favored growth of normal clones in comparison to that of diseased ones. Sugars varied in their inhibitory influence at the 4.0% level. Dextrose, levulose, and lactose at 1.0% proved better than sucrose for the growth of all except one fast‐growing gall clone which grew best with sucrose. However, at 0.125% sugar levels, even in cases where high yields were obtained, the physical character of the tissues changed to dry, brownish, and very friable. Thus, the original callus from normal and gall tissues contained cells with diverse characteristics. The various clones developed used the same sugars but varied strikingly in the rate and type of growth on certain sugars.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1962.tb14952.x

出版商:Wiley    

年代:1962

数据来源: WILEY