Anther Cuticle Research Articles

Embryology of theaceae — Anther and ovule development ofAdinandra, Cleyera andEurya

Anther and ovule development of the theaceous Ternstroemioideae is reported for the first time on the basis of eight specles of three generaAdinandra, Cleyera andEurya. Anthers of these three genera are similar and can be characterized by the following traits: tapetum of glandular type, anther dehiscing latrorse-introrse, both connective and anther epidermis heavily tanniniferous, and connective and even anther wall layers having abundant druses. Their ovules are also very similar in being bitegmic and tenuinucellate, and in having a micropyle formed by the inner integument only, three cell-layered integuments, a raphe bundle terminating at chalaza, usually amphitropous or less often campylotropous ovule, embryo sac formation of Polygonum type, ephemeral antipodal cells, and tanniniferous ovule epidermis. Such ovules are readily distinguishable from those of Camellioideae and all other families. It is suggested that the three genera studied are closely related, and that the degree of embryological specialization is highest inAdinandra and lowest inEurya. On the basis of the significant embryological discrepacies, the Ternstroemioideae seem to have diverged rather distantly from the other core-subfamily Camellioideae of the Theaceae.

Anther-specific, developmentally regulated expression of genes encoding a new class of proline-rich proteins in sunflower

We have used RNA gel blot analysis to demonstrate the anther-specific expression of three genes in sunflower. Expression of these genes was first detected shortly before flower opening, which occurs sequentially on the sunflower inflorescence, and continues during pollination. In contrast, these genes are not expressed (or only weakly expressed) in a male-sterile line in which anther development aborts. In situ hybridization experiments showed that these genes are only expressed in the single cell layer of the sunflower anther epidermis. In the case of one of these genes, which codes for an abundant mRNA, we report the peptide sequences deduced from the sequence of two similar but non identical cDNAs. These proteins contain a potential signal peptide and are characterized by the presence of a proline-rich region which reads KPSTPAPPPPPP(PP)K. Our results also suggest that several proline-rich proteins of unknown functions are specifically synthesized during the maturation of anthers in sunflower.

Scanning electron microscopic observations on morphogenesis of the panicle and spikelet in rice plants.

Morphogenesis of panicle and spikelet in paddy rice, cultivars Yuhkara and Fujihikari was studied by SEM. Germinated seeds planted in containers with submerged soil were cultured under natural conditions. The young panicle and spikelet were dissected and fixed every day until heading with modified Karnovsky's solution with 5% aclorein, dehydrated with acetone, and were dried at critical point, and then coated with gold for investigation. At the panicle primordium differentiation stage (PDS), the ratio of height to width (H/W) in the apical meristem (AM) decreased from one to 0.4 and 0.2 at the palea and stamen PDS respectively. Before the lemma and palea completely covered the inside floral organs, the stamen primordium differentiated to the anther and filament, and pistil primordium to ovule and ovary wall. A central stamen in the lemma side was located at the lowest position among all stamens. This indicated that the three stamens located in the lemma side may be situated at lower positions than the palea-sided organs. When the ridged cuticle (RC) in the anther epidermis began to develop at the meiotic stage of pollen mother cell (PMC), stigma cell started to differentiate, forming stigma hairs when RC covered the anther epidermis. RC changed to a more complicated structure almost at the same time as xylem vessel differentiated in stigma vascular bundles. Therefore, this structural change was considered to have some correlation with sclerification or shrinking of inner anther wall cells. Development of orbicules on the surface of pollen and tapetum cells was discussed.

Reproductive Anatomy and Morphology of Myrtales in Relation to Systematics

Evidence from reproductive morphology and anatomy (excluding palynology) favors an inclusive Myrtales of 11 core families (see below) over either a much broader Myrtales, as advocated, for example, by the Englerian school (most recently Melchior, 1964) or a narrower Myrtales and accompanying Lythrales, as advocated by Novak (1961, 1972) and more recently and in a rather different manner by Briggs and Johnson (1979), who, however, withdrew their concept in this symposium (Johnson & Briggs, 1984; see also argumentation in the appendix in Schmid, 1980). Embryology provides the best evidence for a concept of core Myrtales consisting of Combretaceae, Crypteroniaceae, Lythraceae, Melastomataceae sensu lato, Myrtaceae (including Psiloxylaceae3 and Heteropyxidaceae; Schmid, 1980), Oliniaceae, Onagraceae, Penaeaceae, Punicaceae, Sonneratiaceae, and Trapaceae (familial arrangement strictly alphabetical; see also Tobe & Raven, 1983a). The following embryological traits unite core Myrtales: anthers tetrasporangiate*, with conspicuous endothecium*, glandular tapetum, simultaneous cytokinesis; ovules anatropous*, bitegmic*, crassinucellate; antipodals ephemeral or absent*; endosperm nuclear*; seeds exalbuminous*. The asterisks indicate that exceptions are known. Table 1 (pp. 834-835) lists such exceptions, which in some cases are known for only one family or even only one species, for example, the trisporangiate anther of Corynanthera flava of Myrtaceae (Green, 1979). Other embryological features such as nuclear condition of pollen at time of shedding, persistence of anther epidermis, and types of anther wall development, embryo sac, and embryogeny vary appreciably (see Table 1). Significantly, Dahlgren and Thorne (1984) and Tobe and Raven (1983a) independently arrived at a very similar complex of embryological characters unifying core Myrtales. Reproductive anatomy, that is, histology and vasculature, gives no special aid in resolving the makeup of Myrtales. Features such as bicollateral bundles (internal or intraxylary phloem) occur in peduncles, inflorescence axes, pedicels, flowers, and fruits of most myrtalean taxa (Schmid, 1972b, 1980, for Myrtaceae and Lythraceae; Schmid, unpubl. data and literature survey for other families). However, bicollateral bundles are really histological markers first described for vegetative parts of Myrtales and other orders (Cronquist, 1981; Dahlgren & Thorn, 1984; Metcalfe & Chalk, 1983; van Vliet & Baas, 1984) and then applied to their reproductive parts. The same pertains to vestured pits, which are unreported for myrtalean reproductive structures, but which occur in Lythraceae, Melastomataceae, Myrtaceae, Alzatea (Schmid, unpubl. data). In Myrtales, amphicribral bundles are common, especially in androecia and placentae (Schmid, 1972b, 1980, for Myrtaceae and Lythraceae; Schmid, unpubl. data and literature survey for other families). However, amphicribral bundles seem related to functional, nutritional factors for reasons elaborated elsewhere (Schmid, 1976, 1978). There are no unifying features of floral vasculature for Myrtales (nor for other orders), let alone Myrtaceae. An axile ovular supply (Schmid, 1972a) is most common and clearly basic; the derived transeptal ovular supply (Schmid, 1972a) occurs variously in Myrtaceae, Oliniaceae, Onagraceae, Punicaceae, and Rhynchocalyx of core Myrtales (Eyde, 1981; Schmid, 1972a, 1972b, 1980, unpubl. data and literature survey), as well as in Lecythidaceae sensu lato, Rhizophoraceae

Immunocytochemical localization of water-soluble glycoproteins, including Group 1 allergen, in pollen of ryegrass,Lolium perenne, using ferritin-labelled antibody

The cellular sites of the glycoproteins Group 1 allergen (glycoprotein 1) and Antigen A (glycoprotein 2) in mature ryegrass pollen have been investigated by immunoelectron microscopy. Radioimmunoassays confirm previous findings of cross-reactivity between the purified glycoprotein antigens at the high immunoglobulin G (IgG) concentrations used for localization. Freeze-drying of anthers followed by anhydrous processing has been employed because of the water solubility and mobility of the glycoproteins. A double-embedding technique has been developed. This involves, first, embedding anthers in the water-soluble plastic resin JB-4, sectioning and incubating in ferritin-labelled antisera by the indirect method. The sections are then embedded in Spurr's resin for ultra-thin sectioning. Both glycoproteins are found in the following sites: (1) exine and intine wall layers; (2) pollen cytoplasm; (3) the orbicules and anther loculus; and (4) the anther cuticle. In the exine arcades and surface and in the anther loculus, the ferritin label is bound to pollenkitt. The finding that the glycoproteins are in similar sites is predictable in view of the cross-specificity of the antisera. The extent of antibody penetration of the plastic sections has been examined; labelling is confined to cut grains and absent from intact grains.

Comparison of anther development in genic male-sterile (ms10) and in male-fertile corn (Zea mays) from light microscopy and scanning electron microscopy

Anther ontogeny of a genic male-sterile mutant (ms 10/ms 10) and a related fertile cultivar of Zea was studied from the primordial stage through to tassel maturity. From material glutaraldehyde–formalin fixed, OsO4 postfixed, and plastic embedded, light microscopy of 0.7-μm sections revealed no developmental differences between the two until the young microspore stage. Vacuolation or cytoplasmic disintegration of tapetal cells was detected in male-sterile anthers at this stage. Disintegration of microspores was not detected until the intermediate microspore stage. By the young pollen stage, tapetal cells were highly disorganized and degeneration of the middle layer and endothecium was apparent. No endothecial wall thickenings developed in male-sterile anthers.In normal anther development in Zea, endothecial thickenings are found only at the anterior and posterior ends of the anther. A highly ridged anther cuticle, which is essentially absent in male-sterile anthers, is a common feature of fertile flowers. Anther dehiscence involves a separation of the epidermis from the underlying parenchyma of the connective to form a large pollen cavity from the two microsporangial locules. This process does not involve endothecial fibrous wall thickenings as they are not present over the bulk of the anther. Formation of the anterior pore is a separate process which involves changes in the endothecium wall thickenings.During normal anther development starch accumulates in the endothecium and epidermis at the precallose stage and disappears during the young microspore stage. No differences were noted in the male-sterile anthers. During the formation of normal pollen, considerable starch accumulation is evident. However, none is deposited at this late stage in the male-sterile anther.