Browsing by Author "Barrett, J."
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- Chloroplast phylogeny of asplenioid ferns based on rbcL and trnL-F spacer sequences (Polypodiidae, Aspleniaceae) and its implications for biogeographyPublication . Schneider, H.; Russell, S. J.; Cox, C. J.; Barker, F.; Henderson, S.; Rumsey, F.; Barrett, J.; Gibby, M.; Vogel, J. C.Molecular phylogenies have been generated to investigate relationships among species and putative segregates in Asplenium, one of the largest genera in ferns. Of the ∼700 described taxa, 71 are included in a phylogenetic analysis using the chloroplast rbcL gene and trnL-F spacer. Our results support Hymenasplenium as the sister lineage to all other asplenioid ferns, and all other putative satellite genera are nested within this asplenioid clade. Instead of the classical and well-recognized separation into Old and New World clades, asplenioid ferns reveal a separation of the deeper branches into tropical and temperate clades. Temperate clades have evolved from tropical, more-basal clades and the phylogeny indicates up to six shifts between temperate and tropical preferences in the evolution of this widespread genus. Implications for speciation processes and biogeographic aspects, including the re-colonization of temperate regions after the last glacial period, are discussed and we present a phylogenetic framework from which the historical biogeography of asplenioid ferns can be inferred for Europe and North America.
- Exogenous sucrose effects on carbohydrate level, flower respiration and longevity of potted miniature rose (Rosa hybrida) flowers during postproduction.Publication . Monteiro, José; Nell, Terril A.; Barrett, J.The effect of continuous injection of exogenous sucrose on single flower postproduction longevity of attached flowers of potted ‘Meijikatar’ miniature roses was studied. At bud showing color, with sepals starting to unfold, plants were moved to interior conditions and started being continuously injected with a solution of 3% sucrose or distilled water. Carbohydrate levels, flower respiration and single flower longevity were assessed. The method presented some variability in the amounts of solution supplied to the plants. Infusion of exogenous sucrose increased attached miniature rose flower longevity by 1.5 days and also increased flower respiration rate. The higher the uptake rate of sucrose solution the longer the flowers lasted. Exogenously supplied sucrose was consumed by increased respiration and consequently, at day 6 after anthesis, no differences were found in nonstructural carbohydrate levels between water and sucrose treatments. However, stem percent of soluble sugars was higher in the sucrose infused plants, suggesting that exogenous sucrose supply not only served as an extra source of respirable carbohydrates but also released stored carbohydrates to flower respiration. At flower death, leaf soluble sugars and total non-structural carbohydrates were higher in the sucrose infusion treatment and, independently of infusion treatment flower soluble sugars and total non-structural carbohydrates positively correlated with flower longevity.
- Genetic structure, reproductive biology and ecology of isolated populations of Asplenium csikii (Aspleniaceae, Pteridophyta)Publication . Vogel, J. C.; Rumsey, F.; Russell, S. J.; Cox, C. J.; Holmes, J. S.; Bujnoch, W.; Stark, C.; Barrett, J.; Gibby, M.The potential for environmental heterogeneity to generate spatial structuring of genotypes in seedplant populations that occupy patchy habitats has been demonstrated by several studies, but little is known about the population structure of pteridophytes occupying patchy environments. In this study we have examined the genetic structure of isolated populations of the rock fern Asplenium csikii, an ecological specialist, growing almost exclusively on perpendicular walls of natural rock outcrops. All genetic variation observed in this taxon was partitioned between localities; no allozyme variation was found within a site and each site was colonized by a single multilocus phenotype (MLP). In total, ®ve di erent MLPs were recorded from the nine localities, with two MLPs present at more than one site.
- High production temperature increases postproduction flower longevity and reduces bud drop of potted, miniature roses ‘Meirutral’ and ‘Meidanclar’Publication . Monteiro, José; Nell, Terril A.; Barrett, J.The effect of two temperature regimes (29 °C day/24 °C night and 24 °C day/18 °C night) and of a 4-hour night interruption, during production, was studied on postproduction flower longevity and bud drop of ‘Meirutral’ and ‘Meidanclar’ potted, miniature roses (Rosa L. sp.). High production temperatures increased postproduction flower longevity and decreased postproduction bud drop. In ‘Meidanclar’, the high production temperature increased incidence of malformed flowers. No effects of night interruption could be shown on either postproduction flower longevity or bud drop.
- Phylogenetic and biosystematic relationships in four highly disjunct polyploid complexes in the subgenera Ceterach and Phyllitis in Asplenium (Aspleniaceae)Publication . Pinter, I.; Bakker, F.; Barrett, J.; Cox, C. J.; Gibby, M.; Henderson, S.; Morgan-Richards, M.; Rumsey, F.; Russell, S. J.; Trewick, S.; Schneider, H.; Vogel, J. C.Phylogenetic studies using DNA sequences of two chloroplast regions, rbcL and trnL-F, demonstrate that the proposed genus Ceterach is a small clade within the large genus Asplenium, and sister to the Phyllitis clade. The Ceterach clade is characterised by irregular anastomosing veins and often densely scaled leaf blades. Its taxonomic status as a group nested within Asplenium is confirmed, and it is accepted here as a subgenus with seven species. The Ceterach clade comprises four lineages that correspond to disjunct polyploid complexes: the A. aureum clade forming a polyploid complex (4´, 6´, 8´) in Macaronesia, the A. ceterach clade forming a polyploid complex (2´, 4´, 6´) in the Mediterranean Basin, the A. paucivenosum clade (4´, 6´) in central Asia, and the A. dalhousiae clade (2´) with a disjunct distribution in the Himalaya,Yemen and Eritrea, and southwestern North America. Asplenium paucivenosum is sister to all other members of the Ceterach clade, whereas A. dalhousiae is sister to the A. aureum clade that includes tetraploid A. aureum, hexaploid A. lolegnamense, and octoploid A. parvifolium. Asplenium ceterach and its variations – including the hexaploid A. ceterach subsp. mediterraneum subsp. nov. first described below – form a monophyletic unit, sister to a clade consisting of A. aureum and A. dalhousiae. Asplenium cordatum from Africa and A. haugthonii from the isolated atlantic island of St. Helena are not members of the Ceterach clade, which suggests that leaf blades with dense indumenta have evolved at least twice within asplenioid ferns. The allotetraploid species A. hybridum has the chloroplast DNA from A. ceterach, and therefore the latter species is the maternal ancestor of the former. The other parent of this hybrid species is A. sagittatum that is nested within the sister clade of Ceterach, the Phyllitis clade comprising A. sagittatum and A. scolopendrium. The findings suggest that the current distribution of Ceterach is either the result of long-distance dispersal or represents fragmented relicts of a previously more widely distributed species.
- Postproduction of potted miniature rose: flower respiration and single flower longevityPublication . Monteiro, José; Nell, Terril A.; Barrett, J.Research was conducted to investigate the relationship between flower respiration and flower longevity as well as to assess the possibility of using miniature rose (Rosa hybrida L.) flower respiration as an indicator of potential flower longevity. Using several miniature rose cultivars as a source of variation, four experiments were conducted throughout the year to study flower respiration and flower longevity under interior conditions. For plants under greenhouse as well as interior conditions, flower respiration was assessed on one flower per plant, from end-of-production (sepals beginning to separate) up to 8 days after anthesis. Interior conditions were 21 ± 1 °C and 50 ± 5% relative humidity with a 12-hour photoperiod of 12 μmol.m–2.s–1 (photosynthetically active radiation). Flower respiration was higher if the plants were produced during spring/summer as compared to fall/winter. ‘Meidanclar’, ‘Schobitet’, and ‘Meilarco’ miniature roses had higher flower respiration rates than ‘Meijikatar’ and ‘Meirutral’. These two cultivars with the lowest respiration rates showed much greater flower longevity if grown during spring/summer as compared to fall/winter. The three cultivars with the higher respiration rates did not show differences in flower longevity between seasons. For plants under greenhouse or interior conditions, flower respiration was negatively correlated with longevity in spring/summer but a positive correlation between these parameters was found in fall/winter. During spring/summer, flower respiration rate appears to be a good indicator of potential metabolic rate, and flowers with low respiration rates last longer.