摘要:

Three different closed flower types were identified in safflower and were classified as arrowhead, bar, and cage. Histological observations revealed that the closed flower condition is caused by a differentiation of epidermal cells into papillae that become interdigited. The primary difference between the three types is the length of the fused edge along the petal lobe. The papillae are pointed and have thickened walls of cutin. Reduced seed set results from changes in the internal environment during microsporogenesis. The expression of each closed flower type is governed by a single gene; the arrowhead, bar, and cage types have, respectively, the genotypesarar, baba, andcoca.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12345.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Parental crosses, backcrosses, repeated backcrosses, and sib matings with several strains ofAchlya bisexualisCoker and Couch have been made. Progeny were tested for sexual reaction with the parental strains. The distribution of sex observed could not be explained on the basis of any simple gene or chromosomal mechanism. Two factors were suggested which may affect the distribution of sex. They are selfing in the female and the complexity of the hormonal system which controls the expression of sex. The inheritance of a cycloheximide‐resistant mutant argues against selfing; however, further studies with other genetic markers are needed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12346.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Association of potassium ions with stomatal movements is reported here for 22 different plants. These includeOphioglossum engelmanni, Ginkgo biloba, andPinus sylvestris.In all 22 plants potassium migrates into the guard cells when stomata open in response to light. In addition, potassium migration into guard cells also occurs with night opening inCrassula argenteaand with rhythmic opening inMimosa pudica.Potassium inside the guard or subsidiary cells, conventionally detected through light microscopic observations of epidermal peels treated with sodium cobaltinitrite reagent, may also be mapped by x‐ray microanalysis of such histochemically treated peels, as was the case in this study. In addition to the potassium migration, we also show the movement of chloride as an accompanying anion inOphioglossum engelmanni, Ginkgo biloba, Plantago rugelii, Begoniasp., andAvena sativa.Eight plants are shown to accumulate potassium inside the stomatal initials or cells of immature stomatal apparatuses; ordinary, immature epidermal cells do not show such an accumulation of potassium. A list in the discussion indicates all the plants in which potassium fluxes associated with stomatal movements have so far been established, including the new examples reported in this paper.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12347.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The entry of blue‐green algae into an aerial root ofMacrozamia communisvia a break in the dermal layers and leading through a continuous cortical channel into the algal zone is reported. Penetration of the algae appears to be mainly in the form of filaments. Intercellular migration of the algae is found to occur after dissolution of host cell middle lamellae, but host cortical cells are also destroyed near some of the algae. Intracellular migration is also suggested to be a likely pathway for the algae as they proceed to the algal zone.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12348.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Growing on shifting sand dunes in central Utah is a small endemic population of agigasform ofA triplex canescens.Whereas normalA. canescensusually grows to a height of three to four feet and occasionally to five or six feet, thegigasform often reaches ten and sometimes twelve feet. All normalA. canescensso far examined (67 populations) have 2n = 36 chromosomes; thegigasform has 2n = 18 chromosomes. Several lines of evidence suggest that thegigasform is a relic diploid and the normal form is an autotetraploid derived from it. The growth rate of seedlings and new twigs is nearly twice as great in the diploid as in the tetraploid. Seed germination is faster and much better in the diploid. The tetraploid is reproductively isolated from the diploid because of a much earlier flowering period. The diploid plants possess many attributes which make them uniquely adapted to the drifting sand dune habitat.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12349.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The effect of specimen topography on x‐ray microanalysis element mapping was studied with an electron microprobe and a scanning electron microscope equipped for x‐ray detection. Using the lemma and palea of rice inflorescences as models, we determined that specimen topography can physically limit the detection of x‐rays and thus lead to erroneous element mapping data. Any geometrical point on a specimen interfering with a straight line from the point of excitation to the detector will cause an absorptive shadow area on the element map. Electrons impinging on a sample surface cause emissions to occur in all directions. Emissions with sufficient energy (x‐rays and backscattered electrons) can strike a topographical point different from the location of the focused electron beam, causing detectable x‐ray excitation. This phenomenon will also result in erroneous element map data. Methods of recognition of specimen topographical effects on x‐ray microanalysis are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12350.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Comparative disc electrophoresis of acidic proteins, basic proteins, and isozymes of esterase, MDH, and peroxidase were performed with aqueous extracts of seeds from seven cultivars belonging to five races ofSorghum bicolorssp.bicolor:bicolor, caudatum, durra, guinea, and kafir. Two disc electrophoretic systems were employed. Acidic proteins were electrophoresed in an anionic system (tris‐glycine buffer,pH 8.3). Basic proteins were electrophoresed in a cationic system (β‐alanin‐acetate buffer,pH 4.5). Soluble proteins were stained with Coomassie brilliant blue. Isozyme activity was detected by using specific enzyme stains and substrates. Each cultivar yielded reproducible, characteristic patterns of distinct acidic and basic proteins. Cultivars belonging to the same race produced identical protein and isozyme patterns. The degree of electrophoretic similarity among races was estimated by calculating similarity index values for each of the 10 possible pairs of races. Bicolor, caudatum, durra, and guinea produced very similar acidic and basic protein patterns and esterase, MDH, and peroxidase isozyme patterns. Differences, however, were observed among all races. All of kafir patterns were significantly different from the patterns of other races. Comparative electrophoresis may provide a new source of taxonomic characters for investigating phenetic and phylogenetic relationships inSorghum.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12351.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Relative 2C nuclear DNA contents were microphotometrically determined from nuclei isolated from eight species ofMicroseris, four species ofAgoseris, andPhalacroseris Bolanderi.The thirteen species are diploid (2n = 18) western North American members of the subtribe Microseridinae, tribe Cichorieae, of the family Compositae. A 7.7‐fold variation in DNA content was detected.Phalacroserishas the highest DNA content andAgoseris heterophyllahas the lowest. Within the generaMicroserisandAgoseris, a 2.8‐ and 3.1‐fold range in DNA content was detected. The higher values were from perennial species, and the lower values were from annual inbreeding species. Both evolutionary increases and decreases in nuclear DNA content have apparently occurred during the differentiation of the subtribe.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12352.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Comparison of leaves from diploidOenothera hookeriplants with leaves of their monoploid derivatives revealed the following differences: the leaves of the diploids are almost twice as thick as those of the monoploids; the diploids have only one‐fifth as many cells per unit leaf area as do the monoploids; leaf tissue of the diploids has an average of 36.3 chloroplasts per cell compared with 27.4 for the monoploids; chloroplasts of the diploids average 4.68 μm in length, those of the monoploids, 3.74 μm; chloroplasts from the diploids contain about seven times more chlorophyll than those of the monoploids and have an average of seven thylakoids per granum compared with an average of only three for the monoploids; the average chlorophylla/bratio for the diploid chloroplasts is 2.98 compared with 3.48 for the monoploids.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12353.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

In the four species studied,Grindelia strictassp.blakei, G. arizonica, G. lanceolata, andPrionopsis ciliata (Haplopappus ciliatus), the female gametophyte develops according to thePolygonum(normal) type from the chalazal megaspore of a row of four. In most cases only two antipodal cells are formed, the micropylar one originally containing two nuclei. The number of nuclei increases in both cells; one or both antipodal cells typically grow laterally into the integument, often extending to near the surface of the ovule. This resembles the condition previously reported inGrindelia squarrosa.Since the four species ofGrindeliahave similar antipodal outgrowths, such outgrowths may be considered typical for this genus. The fact thatPrionopsisresemblesGrindeliain regard to outgrowths from the antipodal cells and differs in this respect from typicalHaplopappushelps to justify its separation fromHaplopappus, and perhaps its suggested merger withGrindelia.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12354.x

出版商:Wiley    

年代:1975

数据来源: WILEY