Spore morphology and wall ultrastructure of Trachypteris species (Pteridaceae)

Trachypteris is a small genus consisting of four species native to America and Madagascar: Trachypteris induta, T.?pinnata, T.?gilliana, and T.?drakeana. The spores of the genus were studied using light microscopy and scanning and transmission electron microscopy. They are trilete, triangular to globose, with equatorial diameter of 29?C58???m and polar diameter of 26?C53???m. The exospore is 0.5?C1.1???m thick, plane, and two-layered. The perispore is 0.3?C6.8???m thick and two-layered. Depending on the species, two different ornamentations were observed: cristated with partially fused cristae, and ridged with partially fused ridges, forming an incomplete reticulum. Globules immersed in the perispore were occasionally observed. The systematic value of the Trachypteris spores is discussed, and their morphology and ultrastructure are compared with those of other related cheilanthoid ferns. The palynological characteristics presented here may be useful for phylogenetic studies within the Pteridaceae, and particularly within the cheilanthoid ferns.     

The spores of Pteris cretica complex (Pteridaceae-Pteridophyta) in America

Spore morphology in the Pteris cretica complex, including Pteris brasiliensis, P. ciliaris, P. cretica, P. denticulata var. denticulata, P. denticulata var. tristicula, P. ensiformis, P. multifida and P. mutilata was examined using light and scanning electron microscope. The spores are trilete, triangular to circular in shape, with an equatorial thickening (= cingulum). Equatorial diameter ranges from 29 to 69 μm, and polar diameter from 18 to 53 μm. Exospore is proximally verrucate and distally rugate, with the exception of Pteris ensiformis, which has cones on both polar faces. Perispore is generally less than 1 μm thick, apparently single-layered in section, and translucent under light microscope. Spheroids were frequently observed on the surfaces of both perispore and exospore. Hyaline spores lacking cingulum were found in all specimens. Pteris brasiliensis, P. cretica and P. denticulata exhibit pronounced polymorphism and, in addition to trilete spores these taxa also produce atypical spores such as tetralete, monolete and intermediate types.     

Morphological characteristics of sporangiospores of the tempe fungus Rhizopus oligosporus differentiate it from other taxa of the R. microsporus group

The fungus Rhizopus oligosporus (R. microsporus var. oligosporus) is traditionally used to make tempe, a fermented food based on soybeans. Interest in the fungus has steadily increased, as it can also ferment other substrates, produce enzymes, and treat waste material. R. oligosporus belongs to the R. microsporus group consisting of morphologically similar taxa, which are associated with food fermentation, pathogenesis, or unwanted metabolite production (rhizonins and rhizoxins). The ornamentation pattern, shape, and size of sporangiospores of 26 R. microsporus group strains and two R. oryzae strains were studied using low-temperature SEM (LT-SEM) and LM. This study has shown that: (1) LT-SEM generates images from well-conserved sporangiophores, sporangia, and spores. (2) Robust spore ornamentation patterns can be linked to all different taxa of the R. microsporus group, some previously incorrectly characterized as smooth. Ornamentation included valleys and ridges running in parallel, granular plateaus, or smooth polar areas. Distribution of ornamentation patterns was related to spore shape, which either was regular, ranging from globose to ellipsoidal, or irregular. Specific differences in spore shape, size, and ornamentation were observed between Rhizopus taxa, and sometimes between strains. (3) R. oligosporus has a defect in the spore formation process, which may be related to the domesticated nature of this taxon. It had a high proportion, 10–31 %, of large and irregular spores, and was significantly differentiated from other, natural Rhizopus taxa as evaluated with partial least squares discriminant analysis. It is remarkable that the vehicle of distribution, the sporangiospore, is affected in the strains that are distributed by human activity. This provides information about the specificity and speed of changes that occur in fungal strains because of their use in (food) industry.     

蕨配子体发育及卵发生的显微结构观察

运用显微观察技术对蕨(Pteridium aquilinum var. latiusculum)配子体发育和卵发生进行了研究。结果表明：(1)蕨孢子黄褐色,四面体形,具三裂缝,接种后3～7 d萌发,经丝状体和片状体阶段发育成原叶体,成熟原叶体雌雄异株或同株。(2)蕨颈卵器产生于生长点下方的表面细胞(颈卵器原始细胞),该细胞经2次分裂形成3层细胞,其上层和下层细胞发育为颈卵器壁细胞,中间细胞为初生细胞,它经2次不等分裂产生3个细胞,分别为卵细胞、腹沟细胞和颈沟细胞;刚产生时,此3个细胞紧贴颈卵器壁,细胞质内液泡较多,随着发育,卵细胞和腹沟细胞之间产生了分离腔,但二者通过孔区相连,在卵细胞上表面可观察到卵膜;此后,颈沟细胞和腹沟细胞逐渐退化,颈卵器壁细胞内具有黑色颗粒物质。连续切片观察发现,成熟卵细胞上表面中央具有受精孔。卵发生的细节尚需超微结构的研究。     

Guaianolide-type sesquiterpene lactones of Montanoa tomentosa subsp. xanthiifolia and M. tomentosa subsp. rosei and the molecular structures of two pumilin analogs

Montanoa tomentosa subsp. xanthiifolia and M. tomentosa subsp. rosei produce guaianolides which are very similar to those previously reported from Berlandiera pumila, B. texana and B. lyatra. The molecular structures of 3α-epoxypumilin and 8-acetyl-9-desacylpumilin-9-methacrylate were determined by single crystal X-ray diffraction.     

Meiotic chromosome pairing in Actinidia chinensis var. deliciosa

Polyploids are defined as either autopolyploids or allopolyploids, depending on their mode of origin and/or chromosome pairing behaviour. Autopolyploids have chromosome sets that are the result of the duplication or combination of related genomes (e.g., AAAA), while allopolyploids result from the combination of sets of chromosomes from two or more different taxa (e.g., AABB, AABBCC). Allopolyploids are expected to show preferential pairing of homologous chromosomes from within each parental sub-genome, leading to disomic inheritance. In contrast, autopolyploids are expected to show random pairing of chromosomes (non-preferential pairing), potentially leading to polysomic inheritance. The two main cultivated taxa of Actinidia (kiwifruit) are A. chinensis (2x and 4x) and A. chinensis var. deliciosa (6x). There is debate whether A. chinensis var. deliciosa is an autopolyploid derived solely from A. chinensis or whether it is an allopolyploid derived from A. chinensis and one or two other Actinidia taxa. To investigate whether preferential or non-preferential chromosome pairing occurs in A. chinensis var. deliciosa, the inheritance of microsatellite alleles was analysed in the tetraploid progeny of a cross between A. chinensis var. deliciosa and the distantly related Actinidia eriantha Benth. (2x). The frequencies of inherited microsatellite allelic combinations in the hybrids suggested that non-preferential chromosome pairing had occurred in the A. chinensis var. deliciosa parent. Meiotic chromosome analysis showed predominantly bivalent formation in A. chinensis var. deliciosa, but a low frequency of quadrivalent chromosome formations was observed (1 observed in 20 pollen mother cells).     

THE SPORE PATTERN IN SOME SPECIES OF CHEILANTHES

Of the 32 taxa examined, 13 contained 32 spores in each sporangium and are considered apo-gamous, 14 were sexual species with 64 spores per sporangium, and 5 had 32 spores in some sporangia and 64 in others. When considered as a whole, the spores ranged in size from 29.9 to 74.88μ. Most species had oval or globose spores but several had tetrahedral spores. The spores of all were radially symmetrical. Almost all of the species possessed a crassimarginate type of laesura and all except C. cooperae and C. viscida had a perispore. The ornamentation of the perispore showed the following patterns: napate, granulate, psilate, lobate, foveate, and echinate. The exine pattern was predominantly psilate but foveate, rugulate, napate, and granulate conditions were observed. Seventeen taxa were found to have some degree of spore abortion.     

Pollen morphology of Hosta Tratt. in China and its taxonomic significance

In this study, pollen morphology of 11 taxa of Hosta in China, three Chinese species, five introduced species, and three cultivars, was observed by scanning electron microscopy (SEM) and compared with that of related genera (Hemerocallis, Agave, and Yucca). Pollen grains of Hosta were long-ellipsoidal or ellipsoidal, 20?C65?×?52.5?C142.5???m in size, bilaterally symmetrical, and monosulcate on the distal face. Reticulate and rugulate exine ornamentation was observed in different taxa, and the rugulate type can be further divided into rugulate, rugulate?Cbaculate, and rugulate?Cgranulate subtypes. The exine ornamentation may have evolved in the order: reticulate????rugulate????rugulate?Cbaculate????rugulate?Cgranulate. Furthermore, the rugulate exine ornamentation was the predominant ornamental type in Hosta except for one species with the reticulate type; this is markedly different from that of Hemerocallis, Agave and Yucca. Thus, our data support the proposal by Dahlgren and Clifford (The Monocotyledons: a comparative study. Academic Press, London, 1982) that these Hosta species constitute an independent family?CHostaceae.     

Seed Surface Architecture and Random Amplified Polymorphic DNA Profiles of Paulownia fortunei, P. tomentosa and their Hybrid

The surface patterns of winged seeds of Paulownia fortunei,P. tomentosa and P. fortuneixP. tomentosa were examined by scanningelectron microscopy. The pattern of reticulation on the wingsand seed coat of P. fortunei and the hybrid are comparable,while that on P. tomentosa is different and more elongated.Also, the wings are more extended at the oblong ends of theseeds in the former when compared to the wings of P. tomentosa.Distinct random amplified polymorphic DNA (RAPD) patterns wereobtained for the three taxa and P. kawakamii with five differentrandom oligonucleotide primers, suggesting that the method canyield genetic markers for differentiating the taxa. Also, Southernblot analyses of the RAPD products of the hybrid and the twoparent species revealed shared (inherited) genetic polymorphisms.Copyright 1999 Annals of Botany Company Paulownia species and hybrid, seed surface architecture, reticulated thickening, RAPD markers, Scrophulariaceae.     

Some notes on Marattia anglica from the Jurassic of Yorkshire

In this paper the spores of the Jurassic fern Marattia anglica are redescribed. It appeared that at least 30% of the spores have a more or less trilete, instead of the usual monolete, laesura. In Marattia muensteri, M. hoerensis and M. crenulata (three species from the Jurassic), trilete spores also appeared to occur, although in much lower percentages than in M. anglica. The spores of M. anglica are compared with recent Marattia spores and with Jurassic dispersed spores.Furthermore, the systematic position of M. anglica and other Jurassic Marattia species is discussed.     

Sesquiterpene lactones of Montanoa guatemalensis and Montanoa tomentosa subsp. Xanthiifolia

New 4,5-epoxygermacra-12,6β-olides from Montanoa guatemalensis and a Guatemalan disjunct collection of M. tomentosa subsp. xanthiifolia are reported. These compounds were unlike those from the 10 other Mexican collections of M. tomentosa previous investigated.     

Spore morphology of Serpocaulon A.R.Sm. and related taxa from Brazil (Polypodiaceae)

The epiphytic fern genus Serpocaulon (Polypodiaceae) comprises 42 species nested within the neotropical clade of the family together with genera such as Campyloneurum, Grammitis, Microgramma, Niphidium, Pleopeltis, Pecluma, Polypodium and Terpsichore. Although Serpocaulon is a well-supported genus, its intra-specific relationships are still not completely resolved. The morphological dataset for Serpocaulon and related genera is therefore expanded here with information on spore morphology to provide additional information for phylogenetic consideration. Spores have been collected from herbarium vouchers and acetolysed for light and scanning electron microscopy. All members of the neotropical clade have monolete spores, except for Grammitis and Terpsichore, which have trilete spores. Both verrucate and papillate ornamentation types are recognised. The palynological analysis shows close similarity between spores of Serpocaulon, Campyloneurum, Pleopeltis and Polypodium and supports close phylogenetic relationships between these taxa. Species of the grammitid clade, although nested within the Polypodiaceae, have spore morphology that supports a separate position.     

Seed morphology under SEM and light microscopy in Kansas Juncus (Juncaceae)

Seed morphology was studied in 15 species of four subgenera ofJuncus occurring in Kansas, to determine if seeds provide traits useful in assessing systematic relations within the genus. In this study seed size and shape were of limited value, while surface ornamentation of the hard inner seed coat provided encouraging results. SubgenusPoiophylli showed little variation in surface ornamentation among taxa; similar ornamentation was observed in subgenusGenuini. SubgeneraGraminifolii andSeptati were separately distinct with the taxa in theSeptati forming a continuum of variation.     

The in vivo production of Bacillus popilliae var. rhopaea spores

The effect of various factors on the yield of Bacillus popilliae var. rhopaea spores formed in Rhopaea verreauxi larvae have been studied. Lack of adequate food, temperatures above and below 23°C, and infecting doses above 10⁶ spore larva, all significantly lowered spore yield per larva. Larval age had a pronounced effect; second-instar and young third-instar larvae produ ed about 1 × 10¹⁰ spores while old third-instar larvae produced about 4 × 10¹⁰ spores. Incubation of larvae for longer than 4 weeks did not increase spore yield per larva. Yields were similar whether larvae were infected by injection or per os. Three other host species could be used to mass-produce B. popilliae var. rhopaea spores but all were less efficient than R. verreauxi. Milky third-instar R. verreauxi larvae, which were field collected, yielded 1.57 × 10¹⁰ spores per larva.     

Rosularia globulariifolia var. pallidiflora comb. et stat. nov. (Crassulaceae)

Rosularia globulariifolia (Fenzl) A. Berger and R. pallidiflora (Holmboe) Meikle were originally described as species in Umbilicus DC. in 1842 and 1914, respectively. In the present study, morphological and palynological features were examined in detail to determine the status of these taxa. The general characteristics, seed structure and micromorphology, pollen measurements and pollen characteristics were established. Morphologically, the two taxa cannot easily be distinguished. Pollen grains of both species are tricolporate, subspheroidal and eutectate, ornamentation is psilate and exine structures are similar. Based on morphological and palynological similarities, and the fact that both taxa are found in the same habitats, we propose that R. pallidiflora should be reduced to the rank of variety as Rosularia globulariifolia (Fenzl) A. Berger var. pallidiflora (Meikle) Minareci & K. Yildiz comb. et stat. nov.     

Morphological and molecular (RAPD) analyses confirm the hybrid origin of the diploid grassCalamagrostis longiseta var.longe-aristata (Gramineae)

To examine the hybrid origin of the diploid grassCalamagrostis longiseta var.longe-aristata, we performed morphometric and genetic analyses of this taxon and its putative parental taxa. The morphometric analyses revealed that, in general,C. longiseta var.longe-aristata is morphologically intermediate betweenC. longiseta var.longiseta andC. fauriei. Previous studies have reported that some hybrids exhibit transgressive characters but others do not; the latter is the case forC. longiseta var.longe-aristata. Their absence may be due to the ecological adaptation to environments intermediate between those inhabited by the putative parental taxa, and therefore the transgressive characters have not been selected. Nevertheless, there is no direct evidence for adaptive value of the characters examined in this study and only a small part of all characters potentially responsible for adaptation was investigated. An alternative hypothesis about the absence of transgressive characters inC. longiseta var.longe-aristata is that it is at an early stage of hybrid speciation. Random amplified polymorphic DNA (RAPD) analyses showed that individuals ofC. longiseta var.longe-aristata were placed in both of the clusters formed by each putative parental taxon. Greater genetic diversity was observed inC. longiseta var.longe-aristata than in its putative parental taxa. All here reported findings support the scenario thatC. longiseta var.longe-aristata is of hybrid origin, having evolved fromC. longiseta var.longiseta andC. fauriei.     

SPORE MORPHOLOGY IN THE GENUS BRUCHIA SCHWAEGR. (MUSCI)

Scanning electron microscopy observations of the spores of Bruchia have resulted in the recognition of four spore types based on the ornamentation of the distal spore surface: warty or verrucate, pitted, reticulate, and spinose. The proximal surface of the spores of all species, except B. brevipes, is characterized by a central aperture region surrounded by a triangular murus or rows of spinae forming a triangle and 1 or 2 smooth or verrucate collars. The ornamentation patterns observed are considered to be characteristic for the genus. Spore morphology alone can rarely be used to distinguish species but in conjunction with certain other characteristics, it is an important taxonomic feature. Spore morphology is a major characteristic used to define the limits of the highly variable species B. flexuosa (spinose spores) and to distinguish it from the closely related species B. texana (reticulate spores). Variations in ornamentation patterns within the genus support the recognition of two subgenera (subgenus Bruchia and subgenus Sporledera). Spore morphology also supports the close relationship between Bruchia and Trematodon and is sufficient to eliminate several questionable taxa from the genus.     

团扇蕨孢子发生和发育的显微观察

利用光学显微镜对膜蕨科（Hymenophyllaceae）团扇蕨(Gonocormus minutus(Blume) Bosch)孢子的发生和发育进行了观察。研究结果表明：团扇蕨孢子为多边圆形,三裂缝不明显,外壁表面光滑,周壁薄,紧贴外壁表面,由周壁形成乳头状或颗粒状纹饰。在外壁形成后期,孢子表面和囊腔中出现大量小球;在周壁形成时期,孢子表面和周围出现较多小球体;小球和小球体参与孢子壁的形成。团扇蕨绒毡层为混合型,内层为周原质团绒毡层;外层为腺质型绒毡层。本文为膜蕨科系统演化和发育生物学研究提供依据。