Mating system and stigmatic behaviour during flowering of Alpinia kwangsiensis (Zingiberaceae)

 Little is known about the breeding systems of tropical perennial ginger species. In this paper, we provide information about the breeding system of Alpinia kwangsiensis in Yunnan, Southwest China, specifically self-compatibility, mechanisms promoting outcrossing, and the visitation characteristics of pollinators. Populations of A. kwangsiensis have two specific phenotypes that differ in flowering behaviour: 1) “cataflexistyle” individuals in which the stigma is held erect above the dehiscent anther when anthesis begins in the morning and becomes decurved under the anther at noon and 2) “anaflexistyle” individuals in which the receptive stigma is decurved under the indehiscent anther first and moves into a reflexed superior position above the anther as it begins to shed pollen at mid-day. The stigmatic movements in the two floral phenotypes, which occur in a ratio of 1:1 in natural populations, are synchronous and correlate with the foraging behaviour of floral visitors; pollination is effected only between floral forms. Field experiments indicate that A. kwangsiensis is self-compatible and dependent upon insects for fertilization. This newly reported floral mechanism, which we have named “flexistyly,” adds to the repertoire of devices that have evolved in flowering plants to insure outcrossing. Received November 29, 2001 Accepted January 8, 2002     

Embryology of <Emphasis Type="Italic">Petrosavia</Emphasis> (Petrosaviaceae,Petrosaviales): evidence for the distinctness of the family from other monocots

The affinities of Petrosavia, a rare, leafless, mycoheterotrophic genus composed of two species indigenous to East to Southeast Asia, have long been uncertain. However, recent molecular analyses show that the genus is sister to Japonolirion osense. Japonolirion and Petrosavia comprise the Petrosaviaceae, which are now placed in its own order, Petrosaviales, distinct from other monocots based on molecular analyses. We conducted an embryological study of Petrosavia, comparing it to Japonolirion, as well as to basal monocots (Acorus and Araceae) and more derived monocots (Nartheciaceae, Velloziaceae, and Triuridaceae). Our results showed that Petrosavia is very similar in embryology to Japonolirion, with both genera sharing a glandular anther tapetum, simultaneous cytokinesis in microspore mother cells, anatropous and crassinucellate ovules, T-shaped tetrads of megaspores, ab initio Cellular-type endosperm, and a mature seed coat composed of the exotesta, endotesta, and endotegmen. The two genera of Petrosaviaceae are clearly distinct from Acorus, and all Araceae, Nartheciaceae, Velloziaceae, and Triuridaceae genera in various combinations of characters. Thus, both molecular and embryological evidence support the distinctness of the Petrosaviaceae from other monocots and its placement in its own order, Petrosaviales.     

The tapetum and systematics in monocotyledons

This paper critically reviews the homologies and distribution of tapetum types in monocotyledons, in relation to their systematics. Two main types of tapetum are widely recognised: secretory and plasmodial, although intermediate types occur, such as the “invasive” tapetum described inCanna. In secretory tapeta, a layer of cells remains intact around the anther locule, whereas in the plasmodial type a multinucleate tapetal plasmodium is formed in the anther locule by fusion of tapetal protoplasts. In invasive tapeta, the cell walls break down and tapetal protoplasts invade the locule without fusing to form a plasmodium. When examining tapetum type, it is often necessary to dissect several developmental stages of the anthers. Secretory and plasmodial tapeta are both widely distributed in monocotyledons and have probably evolved several times, although there may be some systematic significance within certain groups. Among early branching taxa,Acorus andTofieldia have secretory tapeta, whereas Araceae and Alismatales are uniformly plasmodial. The tapetum is most diverse within Commelinanae, with both secretory and plasmodial types, and some Zingiberales have an invasive tapetum. Lilianae (Dioscoreales, Liliales, and Asparagales) are almost uniformly secretory.     

Sucrose and starch catabolism in the anther of <Emphasis Type="Italic">Lilium</Emphasis> during its development: a comparative study among the anther wall,locular fluid and microspore/pollen fractions

In order to better understand the various pathways of sucrose and starch catabolism in the anther of lily (Lilium hybrida var. “Enchantment”), invertase (EC 3.2.1.26) and amylase (EC 3.2.1.1, EC 3.2.1.2) activities were measured separately in different fractions (anther wall, locular fluid and microspore/pollen) and correlated with the sugar content during anther development. Our findings showed significant differences among the fractions analyzed, suggesting that the regulation of sucrose and starch catabolism could follow distinct pathways in each fraction. Glucose and fructose amounts progressively decreased from anther wall to fluid and from fluid to microspore/pollen. Thus, the developing pollen could act as a sink for the carbohydrates that reach the anther. In this sense, cell wall-bound invertases seem to play a major role in soluble sugar partitioning in the different fractions of the anther. Sucrose concentration was found to be substantially higher in the locular fluid than in the other fractions, indicating a probable site for storage. On the other hand, the anther wall tissues could have a buffering function, storing nutrient surplus in starch grains and thus regulating the availability of soluble sugars in the whole anther. All these results proved the advantages of the experimental model proposed here, as well as its usefulness to investigate sugar metabolism in Lilium anthers.     

Encystment Processes and the “Matrioshka-like Stage” in a Moss-dwelling and in a Limnic Species of Eutardigrades (Tardigrada)

Tardigrades have two forms of dormancy, namely cryptobiosis and encystment. The encystment is a form of diapause known for a limited number of species of tardigrades and still little studied. To increase the knowledge on encystment, two species of eutardigrades from Italy have been considered: the moss-dwelling Amphibolus volubilis (Eohypsibiidae), and the limnic Dactylobiotus parthenogeneticus (Murrayidae). Cysts have been collected in nature, or induced under laboratory conditions. In the latter case, it was possible to follow the several steps of encystment processes. Two different types of cyst (“type 1” and “type 2”) have been found in A. volubilis, while in D. parthenogeneticus only one type has been found. In general, the ovoid-shaped cysts are constituted by a series of cuticles surrounding the animals and resemble an onion or a Matrioshka Russian doll. In all three types of cyst, the encystment processes show both common and peculiar traits. Encystment begins with the discharging of the sclerified parts of the buccal-pharyngeal apparatus, as in the molting process, but without the loss of the old cuticle. Then, two or three new cuticles are serially synthesized, according to cyst type. In A. volubilis, the ultrastructure of these new cuticular involucra is similar to that of non-encysted animal cuticles, while in D. parthenogeneticus the ultrastructure of the new cuticular involucra differs from that of non-encysted animal cuticle. A modified buccal-pharyngeal apparatus has been observed both in “type 2” cyst of A. volubilis and in the D. parthenogeneticus cyst.     

Flowering response oflemna paucicostata in japan

Twenty-two strains ofLemna paucicostata collected from various districts in Japan are classified into 4 types having different morphological features and photoperiodic behaviors. (I) The “N-1” type, widely distributed in north and middle Japan, consists of many short-day strains with similar morphological characteristics. The strain of northern origin, however, has a shorter critical dark period than that of southern origin, and most of the strains flower in response to a single short day though some from middle Japan require 2 short days. (2) The “N-2” type, found in a limited area of northern Japan, is also a short-day type, but has very long critical dark periods and requires 3–5 short-day cycles for flowering. (3) The “S” type, distributed in southern Japan, never flowered in any photoperiod or culture conditions tested. (4) The “K” type, strain 351, collected at the experimental farm of Kyoto University, is a day-neutral type and flowers independently of photoperiod. Application of some SH inhibitors, tungstate or EDTA, or exposure to blue, far-red or low-intensity light caused daylength-independent flowering in short-day strain 6746 (California origin), but none of these treatments caused flowering in any short-day strain collected in Japan.     

Structure peculiarities of cell walls of <Emphasis Type="Italic">Acremonium chrysogenum</Emphasis>—an autotroph of cephalosporin C

Alterations of cell walls of Acremonium chrysogenum occurring at intensive synthesis of cephalosporin C has been studied. It is shown, using electron microscopy, that the cell wall of the cells of ATCC 11550 strain (“wild” type) became looser and thicker during growth. The cell wall of the cells of strain 26/8 (hyperautotroph of cephalosporin C) considerably degraded by the end of the stationary phase. Biochemical analysis has shown that these alterations entailed decrease of the proteins’ content covalently or noncovalently linked with the polysaccharides of cell walls of both strains. An increase of sensitivity of cell walls of the strain-hyperautotroph to an activity of lytic enzymes of chitinase, laminarinase, proteinase K, and lyticase preparation has been observed during the growth, but this increase has not been found in the case of “wild” type strain. The obtained results evidence to the structure failure of the cell wall of A. chrysogenum entailing the intensive creation of antibiotic.     

Variation in stigma morphology – How does it contribute¶to pollination adaptation in Pedicularis (Orobanchaceae)?

 Stigma morphology in Pedicularis and its role in pollination have not been evaluated. This paper reports for the first time the relationship between stigma morphology and other aspects of floral design. 17 species of Pedicularis representing all the different types of corolla structure in the genus were studied in the field and in the laboratory. Results indicate that the stigmatic surface morphology of Pedicularis species is related to the type of corolla structure occurring in the species. Pollination studies in eight Pedicularis species demonstrated adaptation between stigmatic surface morphology and other aspects of floral biology. Species with larger, more corrugated stigmatic surfaces always possess a subsidiary construction (“tooth” or “beak”) on the galea. In addition, they have relatively longer flower tubes, higher stigmatic pollen loads, bigger pollen size and a shorter blooming period for individual flowers. Finally, the authors discuss the evolutionary significance of floral design in genus Pedicularis. Received April 8, 2002; accepted June 11, 2002 Published online: December 11, 2002     

Age-biased parasitism and density-dependent distribution of fleas (Siphonaptera) on a desert rodent

Parasites often confront conflicting demands when evaluating and distributing themselves among host individuals, in order to attain maximum reproductive success. We tested two alternative hypotheses about host preference by fleas in relation to the age of their rodent host. The first hypothesis suggests that fleas select adult over juvenile rodents because the latter represent a better nutritional resource (the “well-fed host” hypothesis), whereas the second hypothesis suggests that fleas prefer the weaker and less resistant juveniles because they are easier to colonise and exploit (“poorly fed host” hypothesis). We sampled fleas (Synosternus cleopatrae) on the gerbil (Gerbillus andersoni) in 23 different plots in the Negev desert and found an unequal distribution of fleas between adult and juvenile hosts. Furthermore, flea distribution changed as a function of flea density—from juvenile-biased flea parasitism (the “poorly fed host” hypothesis) at low densities to adult-biased flea parasitism (the “well-fed host” hypothesis) at high densities. Other factors that influenced flea preference were soil temperature and the presence of ticks. These results suggest that host selection is not an explicit alternative choice between adults and juveniles (“well-fed host” versus “poorly fed host” hypotheses), but rather a continuum where the distribution between adults and juveniles depends on host, parasite, and environmentally related factors.     

Primary culture and characteristic morphologies of neurons from the cerebral ganglion of the mud crab, <Emphasis Type="Italic">Scylla paramamosain</Emphasis>

Crustacean neurons, obtained from the cerebral ganglion of the mud crab Scylla paramamosain, were successfully cultured in vitro. They maintained typical morphological characteristics and showed better outgrowth in modified Medium 199 (M199) medium than that in Liebowitz’s L-15 medium. Fetal bovine serum (FBS), muscle extracts, and hemolymph of the mud crab S. paramamosain were added as supplements. Only 20% FBS could promote neuron outgrowth, while muscle extracts and hemolymph of S. paramamosain did not improve neuron outgrowth. For cell dissociation, both collagenase type I and trypsin worked well as determined by initial cell viability and following cell outgrowth potential. More than six kinds of cells with different morphological characteristics were identified in the neuron outgrowth. They were “small cells”, “veilers”, “branchers”, “multipolar cells”, “super-large cell”, and “bipolar cells”. Among all of the cells, bipolar cells were identified for the first time in crustacean neurons culture and they could live longer than other cells. The neurons could grow for more than a week before retraction and eventual degradation.     

Basidiocarp development inCoprinus macrorhizus

The dikaryon #5026 (A2B2)+#5132 (A7B7) of the basidiomyceteCoprinus macrorhizus was treated with ultraviolet light (UV),N-methyl-N′-nitro-N-nitrosoguanidine (NG), and 5-bromouracil (BU) in order to induced developmental variations in fruiting. Among a total of 11,383 isolates, 742 were homokaryons. Fruiting test was made with the remaining 10,641 dikaryotic isolates, of which 1,594 showed abnormality in basidiocarp development. Both UV and NG were very efficient in inducing such variations, but BU was not. The induced variations were classified into seven basic types as follows: 1) “knotless”, in which hyphal knots, the first sign of fruiting, do not differentiate; 2) “primordiumless,” in which hyphal knots are formed, but no further development occurs; 3) “maturationles”, in which primordia are formed, but the maturation of primordia into adult fruit bodies does not occur; 4) “elongationless”, in which the elongation of stipe is blocked, and a basidiocarp with a very short stipe is produced; 5) “expansionless,” in which pilei do not expand normally; 6) “sporeless,” in which the formation of basidiospores is blocked and albinic pilei bearing none or only a small amount of spores are produced; and 7) “autolysisless,” in which the autolysis of pilei does not appear to occur. It has been noticed that the four steps of maturation, i.e. stipe elongation, pileus expansion, spore formation, and perhaps pileus autolysis, can proceed independently. Compound types of variations such as “elongation-expansionless,” “elongation-sporeless,” “expansion-sporeless,” and “elongation-expansion-sporeless” were also induced. UV treatment induced maturationless at the highest rate, while NG treatment sporeless. Contributions from the Division of Plant Morphology, Department of Biology, Faculty of Science, Okayama University. No. 117.     

Genetic diversity and relationship of clonal tea (<Emphasis Type="Italic">Camellia sinensis</Emphasis>) cultivars in China as revealed by SSR markers

Tea plant [Camellia sinensis (L.) O.Kuntze)] is one of the most popular non-alcoholic beverage crops in the world today. In recent years, many clonal tea cultivars have been developed and widely planted to replace the diverse traditional tea populations. In this article, we study the relationships between classifications based on simple sequence repeat (SSR) markers and on morphological traits for 185 tea plant cultivars. Results show that the genetic diversity index (H) is between 0.229 and 0.803, and the mean value is 0.543; the observed heterozygosity (H _o) ranges from 0.103 to 0.683, with an average of 0.340, while the genetic identity varies from 0.267 to 0.984. Based on tea-making properties, the genetic diversity in the “black-green tea” group is much higher than in the “Oolong tea” group. Based on morphological traits, cluster analysis classifies the 185 cultivars into three groups, “group I,” “group II” and “group III.” Most cultivars are related based on the geographical origin and their genetic backgrounds.     

Systematics and genetic variation in commercial shape Kappaphycus and shape Eucheuma (Solieriaceae, Rhodophyta)

The systematics and taxonomy of Kappaphycus and Eucheuma (Solieriaceae) is confused and difficult due to morphological plasticity, lack of adequate characters to identify species and commercial names of convenience. These taxa are geographically widely dispersed through cultivation. Commercial, wild and herbarium sources were analysed; molecular markers provided insights into taxonomy and genetic variation, and where sources of genetic variation may be located. The mitochondrial cox2-3 and plastidal RuBisCo spacers were sequenced. There is a clear genetic distinction between K. alvarezii (“cottonii”) and K. striatum (“sacol”) samples. Kappaphycus alvarezii from Hawaii and some samples from Africa are also genetically distinct. Our data also show that all currently cultivated K. alvarezii from all over the world have a similar mitochondrial haplotype. Within Eucheuma denticulatum (“spinosum”) most African samples are again genetically distinct. Our data also suggest that currently cultivated E. denticulatum may have been “domesticated” several times, whereas this is not evident for the cultivated K. alvarezii. The present markers used do not distinguish all the morpho-types known in cultivation (e.g. var. tambalang, “giant” type) but do suggest that these markers may be useful to assess introductions and species identification in samples.     

毛竹的花药发育研究

竹类植物因有着较长的开花周期,其生殖生物学研究的报道相对较少。该研究采用石蜡切片与野外观察的方法,对毛竹花药的发育以及花药发育与花序的关系进行了研究。结果表明:毛竹的花药壁结构包括4层细胞:表皮细胞、药室内壁细胞、中层细胞和绒毡层细胞。药室内壁和中层都只有一层细胞,而且细胞形状较扁,花药发育后期药室内壁会逐渐降解,而中层则会完全解体消失。花药壁的发育为单子叶型,绒毡层为腺质型,而且只有一层,细胞径向较长,最后也会消失。小孢子母细胞减数分裂时,胞质分裂方式为连续型。形成的小孢子经一次有丝分裂后逐渐形成成熟花粉粒,大多为二细胞型,很少产生三细胞型。此外,还发现毛竹花药的发育与花序形态变化存在着相对应的关系。野外连续观察和切片发现,随着花序形态的不断发育变化,首先花药开始形成并不断分化,药壁备层也逐渐形成;接着小孢子逐渐成熟,备层也慢慢随之解体、消失;最后花药逐渐开裂并开始散粉。该研究结果不仅丰富了毛竹和竹类生殖生物学的研究内容,而且对毛竹种质的研究也具有重要意义。     

Chaos in abstract kinetics: Two prototypes

“Spiral-type chaos” and “screw-type chaos” constitute two simple types of nonperiodic oscillatory flow in 3-variable continuous systems. The former type is exhibited, for example, by auniversal system in the switching mode, when the regimens of flow on the two stable branches of the slow manifold in state space are made to differ in an appropriate manner. Screw-type chaos occurs in ahysteresis oscillator between two stable limit cycles, if the rotation gain is positive. For either case, an analogous 2-dimensional “branched papersheet flow” exists. Both flows are determined by a single-variable discrete dynamical system of the Lorenz-Li-Yorke type (as a cross-section), as well as by an equivalent new map. Numerical simulations of two abstract reaction systems giving rise to non-idealized (that is, truly 3-dimensional) flows of either type are presented. The corresponding discrete dynamical systems (Poincaré maps) are 2-dimensional now, having the form of a flattened hairpin (“horseshoe”) in the simplest case. Thus, two actual examples for 3-dimensional flows suspended by a horseshoe diffeomorphism seem to have been found. One contains just a single functionally effective nonlinearity. Real systems of either type may be found in physics, chemistry, biochemistry, biophysics and economy.     

Morphological characterization of single fan-shaped body neurons in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

The fan-shaped body is the largest substructure of the central complex in Drosophila melanogaster. Two groups of large-field neurons that innervate the fan-shaped body, viz., F1 and F5 neurons, have recently been found to be involved in visual pattern memory for “contour orientation” and “elevation” in a rut-dependent manner. The F5 neurons have been found to be responsible for the parameter “elevation” in a for-dependent manner. We have shown here that the F1 neuron also affects visual memory for “contour orientation” in a for-dependent way. With the help of Gal4/UAS and FLP-out techniques, we have characterized the morphological features of these two groups of neurons at single neuron resolution. We have observed that F1 or F5 neurons are groups of isomorphic individual neurons. Single F1 neurons have three main arborization regions: one in the first layer of the fan-shaped body, one in the ventral body, and another in the inferior medial protocerebrum. Single F5 neurons have two arborization regions: one in the fifth layer of the fan-shaped body and the other in the superior medial protocerebrum. The polarity of the F1 and F5 neurons has been studied with the Syt-GFP marker. Our results indicate the existence of presynaptic sites of both F1 and F5 neurons located in the fan-shaped body and postsynaptic sites outside of the fan-shaped body. This work was supported by the “973 Program” (2005CB522804 and 2009CB918702), the National Natural Sciences Foundation of China (30621004, 30625022, and 30770682), and the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-YW-R-28).     

The evolution of pyrroline-5-carboxylate synthase in plants: a key enzyme in proline synthesis

Many plants synthesize and accumulate proline in response to osmotic stress conditions. A central enzyme in the proline biosynthesis is the bifunctional enzyme Δ¹-pyrroline-5-carboxylate synthase (P5CS) that includes two functional catalytic domains: the γ-glutamyl kinase and the glutamic-γ-semialdehyde dehydrogenase. This enzyme catalyzes the first two steps of the proline biosynthetic pathway and plays a central role in the regulation of this process in plants. To determine the evolutionary events that occurred in P5CS genes, partial sequences from four Neotropical trees were cloned and compared to those of other plant taxa. Molecular phylogenetic analysis indicated that P5CS duplication events have occurred several times following the emergence of flowering plants and at different frequencies throughout the evolution of monocots and dicots. Despite the high number of conserved residues in plant P5CS sequences, positive selection was observed at different regions of P5CS paralogous genes and also when dicots and monocots were contrasted.     

Genetic relatedness and genetic diversity of ornamental mei (Prunus mume Sieb. et Zucc.) as analysed by AFLP markers

The genetic diversity and genetic relatedness of mei (Prunus mume; 2n = 16) were studied using amplified fragment length polymorphism (AFLP) markers. Eight EcoRI–PstI AFLP primer combinations were applied to 121 distinct genotypes of mei cultivars and related species. A total of 508 AFLP product bands were produced, of which 382 were polymorphic. The unweighted pair group method with arithmetic averages analysis was carried out based on these AFLP markers. From this analysis, “Qugeng Mei,” “Yan Mei,” “Chaodou Mei,” and mei cultivars were seen to share the same P. mume genetic stem. The AFLP data were able to clearly discriminate P. mume from other species in the genus Prunus, with P. armeniaca aligning as its closest related species. Two major groups and nine subgroups of mei flower were identified, and there was a strong coincidence of these AFLP-based groupings with the respective morphological characters of the accessions. The genetic diversity of mei accessions was greatest in the Yunnan Province and decreased toward Eastern China and Japan, so supporting the hypothesis that the southwest of China represents the genetic diversity center of the species.     

The Au family, a novel short interspersed element (SINE) from Aegilops umbellulata

A novel plant short interspersed nuclear element (SINE) was identified in the second intron of the acetyl CoA carboxylase gene of Aegilops umbellulata which has been designated ”Au”, for the host species in which it was discovered. Au elements have a tRNA-related region, direct flanking repeats, and a short stretch of T at the 3′ end, which are features common to Au and previously characterized SINEs. Au elements are detected in the genomes of several monocots and dicots by DNA dot hybridization and are also found in the tobacco genome by database searching. Au elements are present at an especially high copy number (approximately 10⁴ copies per haploid genome) in wheat and Ae. umbellulata. This suggests a recent amplification of Au in the Triticum and Aegilops species. In situ hybridization revealed a dispersed distribution of Au elements on wheat chromosomes. Au elements were amplified by PCR from monocot and dicot species and the phylogenetic relationships among Au elements were inferred. This phylogenetic analysis suggests amplification of Au elements in a manner consistent with the retrotransposon model for SINE dispersion. The high copy number of Au elements and their dispersed distribution in wheat are desirable characteristics for a molecular marker system in this important species. Received: 15 April 2000 / Accepted: 24 August 2000