Chromosomal distribution of rRNA genes in the karyotypes of two dioicous liverwort species from the genus Pellia Raddi

Over one hundred years have passed since the first cytogenetic studies were made on the liverwort genus Pellia Raddi. The karyotype of Pellia is characterised by large chromosomes, a varying heterochromatin content and the presence of sex chromosomes in the dioicous species. Most of the Pellia species are diploids with n?=?9, but one of them, Pellia borealis Lorb., has been described as an example of allopolyploidy in liverworts. Although the localisation of rRNA genes, which are essential components of the nuclear genome, remains a challenge in bryophytes, data on the number and chromosomal localisation of 35S and 5S rDNA in all of the Pellia species are now available. Previously, fluorescence in situ hybridisation using rDNA probes was performed on the mitotic chromosomes of 2 monoicous species. The aim of this study was to establish the number and chromosomal distribution of rRNA genes in 2 dioicous diploid species—Pellia endiviifolia (Dicks.) Dumort. and Pellia neesiana (Gottsche) Limpr. The relationships between the species within the genus Pellia can now be discussed in the context of the localisation of the rDNA sites and the range in the number of rDNA loci among bryophytes can also be verified.     

Evolution and speciation in Pellia,with special reference to the Pellia megaspora-endiviifolia complex (Metzgeriales), II. Cytology

Abstract

A unique karyotype within the genus Pellia, both in terms of chromosome structure and in the distribution of heterochromatin as defined by Giemsa C-banding, supports the taxonomic recognition of P. megaspora. Resembling P. endiviifolia more closely than P. epiphylla or P. neesiana in its heterochromatin content, the species differs significantly in karyotype symmetry and the absence of an m-chromosome. Comparison of P. endiviifolia from Britain, Japan and Canada has identified clear and extensive evidence of cytological polymorphism.     

Le diterpenoid du gout piquant de Pellia endiviaefolia

A unique pungent component of the new buds of Pellia endiviaefolia is due to a diterpene dialdehyde 2, which was recently isolated from another liverwort, Trichocoleopsis sacculata.     

Evolution and speciation in Pellia,with special reference to the Pellia megaspora-endiviifolia complex (Metzgeriales), I. Taxonomy and distribution

Abstract

The genus Pellia, with three currently recognised species, includes a relatively primitive taxon, P. endiviifolia, in which the perichaetium is high and incised, with an enclosed calyptra. It is dioecious, produces anthocyanin wall pigments in exposed sites, reproduces asexually by repeatedly furcate, narrow fragmenting ‘autumnal innovations’, is freely branched and has relatively small spores. A species previously confused with this taxon, and here described as P. megaspora, is an endemic boreal American species, found from New York, Connecticut and Massachusetts north to Newfoundland and west to Minnesota. The plant has a tall perichaetium that is strikingly incised-ciliate to lacerate. It is dioecious but does not produce wall pigments and autumnal innovations, is simple or oncefurcate and has extremely large spores. Cytological and biochemical data support the specific recognition of P. megaspora. Biochemical data also suggest that Japanese populations currently assigned to P. endiviifolia are distinct and field observation suggests that these plants may represent an autonomous subspecies.     

Spirocyclopropane-type sesquiterpene hydrocarbons from Schinus terebinthifolius Raddi

The essential oil of Schinus terebinthifolius fruits was reinvestigated using GC and GC–MS techniques. Apart from several known compounds three sesquiterpene hydrocarbons with a carbon skeleton exhibiting the rare spiro(cyclopropane) moiety could be isolated by a combination of column chromatography and GLC. Structure assignments were carried out by NMR spectroscopy. These natural products are 9-spiro(cyclopropa)-4,4,8-trimethyl-2-methylenbicyclo[4.3.0]non-1(6)-ene (terebanene), 9-spiro(cyclopropa)-2,4,4,8-tetramethylbicyclo[4.3.0]nona-1,5-diene (teredenene), and (6R1,8R1)-9-spiro(cyclopropa)-2,4,4,8-tetramethylbicyclo[4.3.0]non-1-ene (terebinthene).     

The hybrid origin of the polyploid liverwort Pellia borealis

Isozyme markers were used to investigate the origin of the polyploid liverwort, Pellia borealis (gametophytic n=18), which was believed to represent an autopolyploid form of Pellia epiphylla (n=9). Enzyme variation was studied in four taxa: polyploid P. borealis, two recently discovered sibling species of P. epiphylla complex, and the closely related P. neesiana (n=9). Gametophytes of the polyploid showed a complex electrophoretic phenotype for three diagnostic enzymes (DIA1, MPI1 and ACO) in contrast to simple pattern in all haploid taxa. It was postulated that the pattern found in the polyploid represents a fixed heterozygous phenotype resulting from allopolyploidy. Alleles present in the polyploid were found (with only one exception) in the two sibling species of the P. epiphylla complex, suggesting that they are the parents of the allopolyploid. Pellia neesiana was excluded as a donor of either of the genomes. Variation in the polyploid suggests at least three separate origins of P. borealis.     

A cytological study of Pellia epiphylla (L.) Corda in Britain with reference to the status of Pellia borealis Lorbeer

Abstract

The history of Pellia borealis is outlined and its morphology compared with that of P. epiphylla. The techniques for preparing material for chromosome counts are described. Several gatherings of monoecious Pellia with large epidermal cells (P. borealis) were found to be haploid, n = 9. The size of the epidermal cells is shown to be valueless as a character for distinguishing the two species. It is concluded that only P. epiphylla should be retained as a species.

We wish to record our thanks to Dr S. Arnell for examining British material and for helpful correspondence; to Dr A. J. E. Smith for his valuable advice and criticism, and for the use of cytological facilities; and to all those who have contributed material of possible P. borealis.     

Cytological diversity in Pellia endiviifolia (Dicks.) Dum

Abstract

Extensive cytological variation between British populations of Pellia endiviifolia (Dicks.) Dum. (n = 8+x/y) permits the recognition of six distinct karyotypes; one of them found also in Greece and another in the U.S.S.R. Although based on typically small amounts of constitutive heterochromatin, Giemsa C-banding patterns serve to identify each of three chromosomes, 1, 6 and 9, as dimorphic or polymorphic. Relative proportions of chromosomes differ between karyotypes and further variation relates toa nucleolar organiser region (NOR) on chromosome 6 of one population in addition to the NOR generally located in chromosome 7. These findings have repercussions intaxonomy and reproductive behaviour that are discussed in detail.     

Effects of Chilling on the Ultrastructure and Net Photosynthesis of Pellia epiphylla

Thalli of Pellia epiphylla were collected frozen from natureand chilled artificially for varying lengths of time at –22°C. The survival and recovery of this material was comparedwith that of the non-chilled material by performing CO₂ exchangeexperiments. Electron microscopy was done from the chilled andhardened thalli, and clear differences were observed in theultrastructure of these materials. The vacuoles of the hardenedtissue contained fine granular material but those of the chilledtissue had large electrondense particles embedded in finer granularsubstance. Oil bodies had greatly changed. In the cytoplasmthere were abundant lipid-like bodies resembling oil globulesof oil bodies and particularly in the vacuoles there were oily-lookingflecks. Chloroplasts had large starch grains and the lamellarsystem was somewhat disorganized. Net photosynthesis was highestwith material stored for the longest time at –22 °C. Pellia epiphylla, ultrastructure, net photosynthesis, chilling     

Agrobacterium tumefaciens-mediated transformation of Solanum gilo Raddi as influenced by explant type

An efficient system for Agrobacterium tumefaciens-mediated transformation of Solanum gilo was established. The marker genes for kanamycin resistance and ß-glucuronidase expression were introduced. A comparison between cotyledon and hypocotyl explants showed that while regeneration was better from hypocotyl explants, cotyledon explants gave better transformation efficiency (46% vs. 32%). Four levels of kanamycin selection (100, 150, 200 and 250 mg/l) were tested for effect on transformation efficiency with each type of explant. Lower levels of kanamycin worked better using cotyledon explants, while higher levels of kanamycin worked better for hypocotyl explants. All nine t₀ plants tested for expression of the kan ^r gene were positive. The progeny of three of these plants showed a pattern of classical Mendelian inheritance (3 to 1) for both the kan ^r and the ß-glucuronidase genes.Abbreviations MS Murashige and Skoog (1962) medium - 2,4-D 2,4-Dichlorophenoxyacetic acid - NPTII neomycin phosphotransferase - GUS ß-glucuronidase     

Effects of auxin on wall polysaccharide composition and enzyme activity during extension-growth of Pellia (Bryophyta)

Auxin-induced changes in cell wall polysaccharide composition and enzyme activity of seta segments from the liverwort Pellia epiphylla (L.) Corda were studied using colorimetric, gas chromatographic, radioactive tracer, and viscometric techniques. Extension-growth of segments doubled in the presence of aqueous 10 μ M indole-3-acctic acid (IAA) ± 50 m M glucose. IAA-enhanced growth was accompanied by (1) enhanced synthesis of all wall polysaccharides but cellulose, (2) increase in the relative glucose content of neutral wall sugars, and (3) change in the activity of wall-bound glycosidase relative to controls, but no change in the activity of cellulase. Galactose and mannose (50 m M ) suppressed auxin enhancement of both growth and wall synthesis. These findings suggest that auxin-mediated extension-growth of Pellia setae is dependent upon the maintenance of non-cellulosic cell-wall synthesis.