摘要:

Cytogenetics and embryological studies of male sterility have been reported for the first time inEupatorium tanacetifoliumGill, ex H. et A. (Gyptis pinnatifidaCass.). This species produces viable seeds but abnormal pollen that is not shed by the anthers. There are great abnormalities in karyokinesis and cytokinesis in microsporogenesis that result in irregular sporads formed by 5–10 cells of variable size, shape, and chromosome number. There is an irregular distribution of chromosomes, due to absence of regular pairing and disjunction, presence of chromatinic bridges in most of telophases, and to succesive aberrant cytokinesis without formation of cell plate and with variably oriented walls. The two chromatids of each chromosome presumably remain joined until the end of the process. Somatic chromosome number of 2n= 30 is reported for one population of this species, an apomict taxon of probable triploid origin. Embryo‐sac ontogeny is of theAntennariatype of diplospory, wherein embryo and endosperm development are parthenogenetic.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13445.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Comparative studies on the ultrastructure and protein composition of the embryo and endosperm of date palm (Phoenix dactyliferaL.) were conducted. Cells of the embryo cotyledon and endosperm function in reserve storage and contained cell walls, nuclei, and cytoplasm rich in lipid and protein bodies. Morphometric analysis from light and electron micrographs showed that the cell walls of the endosperm occupied 65% of the total cell volume, but only 6% in the embryo. The protein bodies of the endosperm accounted for 11%, whereas those of the embryo occupied more than half of the total cell volume. The volume of organelles and organelle‐free cytoplasm in the endosperm was negligible, suggesting that most of the extractable endosperm proteins are localized in the protein bodies. Extractable proteins in the embryo may come from cytoplasm, protein bodies, and other organelles. The endosperm contains relatively lower amounts of proteins than does the embryo. Proteins extracted from both tissues were compared using SDS‐polyacrylamide gel electrophoresis, tube gel isoelectric focusing, and two‐dimensional electrophoresis. Proteins of both the tissues were heterogeneous in molecular mass and charge. The majority of the proteins were similar in molecular mass and charge in the two tissues, suggesting that most of the storage proteins are probably the same. However, there were also several embryo‐ and endosperm‐specific proteins apparent in both the first‐ and second‐dimension gels. The endosperm‐specific proteins may play an important role in germination and seedling development.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13446.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

The seed ofWashingtonia filifera(Lindl.) Wendl. is hemispherical and has a smooth testa. The embryo is located on the rounded side of the seed near the raphe. The embryo consists of a prominent single cotyledon, an epicotyl, and a small root apex. The shoot apex is oriented at a right angle to the long axis of the embryo and possesses 2 to 3 leaf primordia. The cotyledon functions as a storage organ and is composed of three cell types with similar ultrastructure. These three types—the parenchyma, protoderm, and procambium—can be distinguished on the basis of position, size, and shape. The procambial strands in the cotyledon consist of a ring of bundles grouped into two distinct sympodia and extend from beneath the shoot apical meristem to the tip of the cotyledon where they are situated very close to the surface. The most prominent organelles within all cell types are protein bodies, lipid bodies, and crystalline protein fibers. The protein bodies contain small crystalline inclusions which are presumed to be phytin. Protein bodies in the protoderm were smaller, denser‐staining, and contained fewer crystalline inclusions than those in the parenchyma or procambium. On a volume basis, the parenchyma was shown to be 43% protein bodies, 25% lipid bodies, 15% cytoplasm, 7% cell wall, 4% intercellular space, 2% nuclei, and 4% other organelles (mitochondria and plastids).

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13447.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Comparative studies on the protein composition of the endosperm and embryo ofWashingtonia filifera(Lindl.) Wendl. were conducted. On a fresh weight basis, the endosperm contained lower amounts of protein than did the embryo. This correlated well with lower volumes of protein bodies and cytoplasm in the endosperm than in the embryo. Endosperm proteins were derived mainly from the protein bodies because the volume of organelle‐free cytoplasm was negligible, whereas the source of the proteins in the embryo may be the protein bodies, organelles, and the organelle‐free cytoplasm. Proteins of the two tissues were compared using SDS‐polyacrylamide, isoelectric focusing and two‐dimensional gel electrophoresis. In the first‐dimension analysis, proteins of the two tissues were heterogeneous in molecular mass and charge. In the first‐ and second‐dimension gels, the majority of the protein bands were similar in the two tissues, but a few bands were specific to each tissue type. The similarities in the proteins suggest that the storage proteins are probably the same in the two tissues. The embryo‐specific proteins are probably derived from cytoplasm and organelles.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13448.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

A statistical analysis of size for the megasporocyte, functional megaspore, and 2‐, 4‐, 8‐nucleate, and mature female gametophytes forGlycine maxandPhaseolus aureusgrown in the field and greenhouse was accomplished from measurements of the length, width, and length and width intercepts for each stage. The greatest increase in mean length forPhaseolusin the greenhouse andGlycinein the field takes place between the 2‐ and 4‐nucleate stages. In alternate environments, the two genera show the greatest increase between the functional megaspore and 2‐nucleate stage. Greater similarity between the genera than shown by each genus in the two environments was also found for other features, viz., the largest mean length and width attained by each stage, the least increase in mean length and width and the overlap in confidence intervals for length and length intercepts between successive stages, and changes in the width intercept as a percent of total width as the ovule becomes campylotropous.Ttests at the 0.05 level reveal significant differences between greenhouse and field plants inPhaseolusfor length of the megasporocyte and 8‐nucleate stage and length and length intercept of the 2‐ and 4‐nucleate stages. InGlycine, differences appear for the length and both intercepts of the megasporocyte and the length intercepts of the mature stage. The similarity ofGlycinein one environment toPhaseolusin the other coupled with the differences of statistical significance for each genus in the two conditions suggest that environment does have a pronounced effect on female gametophyte development. Statements to the contrary in previous reports to include one on these genera are correct for the qualitative aspects of development investigated, but they cannot be extended in all respects to the quantitative analysis of growth reported here. The differences recorded suggest caution in the choice of material for comparative studies. For embryological data, especially those of a quantitative nature, to be fully useful in taxonomic assessments, material for all taxa should be collected from natural habitats.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13449.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Ecological groups were identified from 34 North American species of pine using multivariate analysis of 18 ecological traits. Five adaptive modes are described: 1) fire‐resistant species that are large, thick‐barked, and have large cones and long needles; 2) tall, fast‐growing mesophytic species with moderately high shade tolerance; 3) stress‐tolerant species with animal‐dispersed seeds, occurring mainly on cold or dry sites where fire is infrequent; 4) fire‐resilient species that are precocious reproducers with small seeds, often in serotinous cones; and 5) species of southern mesic sites with fast growth, strong, heavy wood and short persistence of needles. Intermediates between these modes exist. Convergent evolution has occasionally occurred, as shown by high ecological similarity of species in different taxonomic sections withinPinus.However, the analogies between species are imperfect, suggesting the importance of constraint by shared ancestry and divergence produced by a diversity of environments.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13450.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Infection ofRosa woodsiiby some members of the order Hymenoptera results in neoplasmic outgrowths on the leaves. One type of outgrowth produces a spherical swelling (leaf gall) while the other has extensive hair‐like proliferations (hairy gall). The anatomy and ultrastructure of these galls were examined by light microscopy and transmission electron microscopy. The leaf gall cells were considerably larger than normal cells, lacked well‐developed chloroplasts and were loosely arranged with prominent intercellular spaces. Vascular bundles were scattered throughout the gall tissue. The upper three cell layers of the leaf gall tissue resembles a periderm, having many suberin lamellae. The suberin lamellae were often traversed by pores which may represent incomplete plasmodesmata. Phenolic compounds were commonly seen both in the normal and gall cells. A layer of internal cells of the hairy galls have remarkably thickened cell walls, presumably due to the deposition of cellulosic substances. Unlike leaf galls, the epidermal cells of the hairy galls were not heavily cuticularized and no periderm was found. The hair‐like outgrowths present on the outer surface of these galls had a central vascular bundle. The epidermis of the outgrowths also had thickened cell walls, and trichomes occurred on the outer surface. The structural modifications brought about by the insect invasion in these two galls are compared and their roles in gall formation are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13451.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

The leaf and stem of the potato plant (Solanum tuberosumL. cv. Russet Burbank) were studied by light microscopy to determine their morphology and vasculature; scanning electron microscopy provided supplemental information on the leaf's morphology. The morphology of the basal leaves of the potato shoot is quite variable, ranging from simple to pinnately compound. The upper leaves of the shoot are more uniform, being odd pinnate with three major pairs of lateral leaflets and a number of folioles. The primary vascular system of the stem is comprised of six bundles, three large and three small ones. The three large bundles form a highly interconnected system through a repeated series of branchings and arch‐producing mergers. Two of the three large bundles give rise to short, lateral leaf traces at each node. Each of the small bundles in the stem is actually a median leaf trace which extends three internodes before diverging into a leaf. The three leaf traces enter the petiole through a single gap; thus the nodel anatomy is three‐trace unilacunar. Upon entering the petiole, each of the laterals splits into an upper and a lower lateral. Whereas the upper laterals diverge entirely into the first pair of leaflets, the lower laterals feed all of the lateral leaflets through a series of bifurcations. Prior to their entering the terminal leaflet, the lower laterals converge on the median bundle to form a single vascular crescent which progresses acropetally into the terminal leaflet as the midvein, or primary vein. In the midrib, portions of the midvein diverge outward and continue as secondaries to the margin on either side of the lamina. Near the tip of the terminal leaflet, the midvein consists of a single vascular bundle which is a continuation of the median bundle. Six to seven orders of veins occur in the terminal leaflet.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13452.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

The growth of the tropical treeBrownea arizaBenth. is modular and conforms to Troll's model. Distinctive anatomical features of its shoot development were investigated. Each module consists of from 6–10 compound leaves and terminates its growth by shoot tip abortion. Sympodial branch systems are formed by renewal growth from the most distal (pseudoterminal) 1–2 buds. New modules are wholly preformed within large (15–28 cm) buds. The flush occurs without a resting period and full shoot expansion is completed within one day. A distinct abscission zone develops in the stem just distal to the node of the last expanded leaf. Abortion of the shoot apex and 5–6 embryonic leaves occurs 2–3 days after the flush begins. This tissue vacuolates and begins to become necrotic prior to actual abscission. New flushes are pendent but are reoriented to a plagiotropic or upright position to create an arborescent form. Reorientation begins quickly (10° within 2 days) due to maturation of primary and secondary tissues and continues throughout the life of the branch by means of reaction wood formation on the upper surface.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13453.x

出版商:Wiley    

年代:1988

数据来源: WILEY

摘要:

Phenotypic plasticity and genotypic variation were studied inAgropyron repensL. (Beauv.) collected from populations in two grassland communities which differed in the length of time since the last major disturbance. Twenty genotypes were collected from each population. Each genotype was vegetatively propagated, and subjected to six different treatments in a greenhouse. Phenotypic plasticity and genotypic variability were measured as across‐ and within‐treatment standardized variances respectively. Patterns of plasticity were measured by genotype correlations across treatments. The results were presented graphically by the regression method of Garbutt and Zangerl (1983). Analysis of variance revealed significant population, genotype and treatment effects. Significant positive correlations between magnitude and variability of performance were found for all characters. Phenotypic plasticity and magnitude of performance were generally greater in plants collected from the older established field. Evidence for greater specialization in the older population was suggested by negative correlations between performance in the most favorable and least favorable treatments and by greater dissimilarity of genotype response across treatments. A more variable phenotypic response across treatments (i.e., higher plasticity) for plants from the older population may therefore be a consequence of specialization and not an adaptive trait per se.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1988.tb13454.x

出版商:Wiley    

年代:1988

数据来源: WILEY