Sex ratio and sex expression in an urban population of the silver moss,Bryum argenteum Hedw.

ABSTRACT

Introduction. A well-supported pattern among dioicous bryophytes is male rarity. However, few assessments of bryophyte sex ratios have been made across environmental gradients to assess the role of environment in shaping population sex ratios.

Methods. We systematically surveyed 200 shoots from a 20?m² urban population of Bryum argenteum, and regenerated each shoot apex until sex expression occurred (up to 315 days).

Key results. Female shoots outnumbered male shoots 132 to 68, giving a sex ratio of 1.94♀: 1♂. The female bias was found in two transects in higher light environments but not in the third transect, which had a lower light level and an equal sex ratio. Female shoots took longer than male shoots to reach gametangial induction (122 vs. 60 days) and longer to produce 5 inflorescences (120 vs. 80 days). Male shoots produced an average of 10× the total number of inflorescences compared to female shoots (34 vs. 3.5 inflorescences). Despite producing more inflorescences, male plants also produced more regenerant shoots, thus contradicting the prediction that a higher prefertilisation reproductive effort in males trades off with vegetative proliferation. Female plants harboured significantly more associated microbes than male plants.

Conclusions. Our results support the role of light in influencing sex ratios in this species, suggest that trade-offs between reproduction and vegetative growth may not be strong for males, and indicate a potential role of a sex-specific microbiome in influencing sex ratios.     

Chromosome studies on some British and Irish mosses. III

Abstract

A lamellate paraphyllium on the dorsal side of the shoots in Brachiolejeunea laxifolia is described and its origin discussed. It is probably a useful species character, unique in the Lejeuneaceae.     

Three modes of asexual reproduction in the moss Octoblepharum albidum

Abstract

Populations of Octoblepharum albidum growing in very moist and shaded habitats were found to have three kinds of asexual reproduction. First, the production of foliar gemmae along the upper half of leaf margins. Second, the production of protonema gemmae on protonemata originated from foliar gemmae. Third, the production of buds and new shoots at leaf tips. The formation of new shoots is further repeated at the leaf tips of the new shoots, giving the plant the character of a 'walking moss'.     

Protonemal gemmae on Amblystegium serpens (Hedw.) B., S. & G. from Macquarie Island

Abstract

Amblystegium serpens, collected on Macquarie Island, formed protonemal gemmae in laboratory culture. The gemmae germinated to form leafy shoots. They are presumed to be vegetative reproductive structures.     

Cytological Comparison of Leaves and Stems of Prunus Avium L. Shoots Cultured on a Solid Medium with Agar or Gelrite

An axillary proliferating clone of Prunus avium L. was subcul- tured every four weeks on solid MS medium with agar as the gelling agent. Vitrification (hyperhydricity) of shoots was induced in one four week cycle with the same medium except that agar was replaced by gel- rite. During culture on the vitrifying medium, the water content of the shoots progressively increased with a parallel decrease in chlorophyll content. Cytological differences between the leaves and stems of the vitrified and normal shoots were detected by light and electron (both transmission and scanning) microscopy. Leaves of vitrified shoots were characterized by lower number of chloroplasts in the palisade parenchyma and by a defective cuticle. The stems of vitrified shoots had a less developed and lignified xylem tissue, lacked sclerenchy- matic areas and showed hypertrophy of the cortical parenchyma. More intense vacuolar activity with evagina- tions of the chloroplast envelope into the vacuole was noted in cells of vitrified leaves.     

Indirect effects mediated by compensatory shoot growth on subsequent generations of a willow spittlebug

 We investigated whether oviposition by the spittlebug Aphrophora pectoralis on Salix miyabeana and S. sachalinensis in fall 1998 affected shoot growth pattern and further oviposition by subsequent generations of the willow spittlebug in early September 1999 and 2000. Spittlebug oviposition enhanced the growth of current-year shoots on 1-year shoots with oviposition (O-shoots) compared to those without oviposition (N-shoots): the length of current-year shoots increased in 1999 and 2000, the number of current-year shoots increased in 2000 despite a decrease in 1999, and the shoot abscission rate decreased during the 1999 winter. The number of egg masses per current-year shoot was greater on O-shoots than on N-shoots in 1999, and this tendency was reinforced in 2000. The total number of egg masses was greater on O-shoots than on N-shoots in 2000, although there was no significant difference in 1999. There is thus a positive feedback system between spittlebug attack and compensatory growth on willow. Received: April 11, 2002 / Accepted: July 30, 2002 Present address: Center for Ecological Research, Kyoto University, Otsu, Japan Acknowledgments We thank Masanori J. Toda and Andrew Davis for valuable comments and critical reading on this paper. Financial support was provided by a Japanese Ministry of Education, Science, Sports, and Culture Grant-in-Aid for Creative Basic Research to Takayuki Ohgushi. Correspondence to:A. Nozawa     

Effect of iron and manganese on65Zn absorption and translocation in soybean seedlings

Summary Short-term experiments were conducted to determine the effect of varying levels of iron and manganese on⁶⁵Zn absorption by roots and translocation to shoots in soybean seedlings. In 11 hours uptake duration, both iron and manganese depressed the⁶⁵Zn absorption by roots and translocation to shoots. The depression was of higher magnitude at higher levels of iron and manganese (5.0 ppm) in the medium coupled with highest level (5.0 ppm) of zinc concentration. It is concluded that interactions between zinc and iron as well as zinc and manganese occur during absorption and translocation processes.Publication No.1185 under Journal Series of the G.B. Pant University of Agriculture and Technology, Experiment Station, Pantnagar     

Immunochemical detection with rabbit polyclonal and mouse monoclonal antibodies of different pools of phytochrome from etiolated and green Avena shoots

While two monoclonal antibodies directed to phytochrome from etiolated oat (Avena sativa L.) shoots can precipitate up to about 30% of the photoreversible phytochrome isolated from green oat shoots, most precipitate little or none at all. These results are consistent with a report by J.G. Tokuhisa and P.H. Quail (1983, Plant Physiol. 72, Suppl., 85), according to which polyclonal rabbit antibodies directed to phytochrome from etiolated oat shoots bind only a small fraction of the phytochrome obtained from green oat shoots. The immunoprecipitation data reported here indicate that essentially all phytochrome isolated from green oat shoots is distinct from that obtained from etiolated oat shoots. The data indicate further that phytochrome from green oat shoots might itself be composed of two or more immunochemically distinct populations, each of which is distinct from phytochrome from etiolated shoots. Phytochrome isolated from light-grown, but norflurazon-bleached oat shoots is like that isolated from green oat shoots. When light-grown, green oat seedlings are kept in darkness for 48 h, however, much, if not all, of the phytochrome that reaccumulates is like that from etiolated oat shoots. Neither modification during purification from green oat shoots of phytochrome like that from etiolated oat shoots, nor non-specific interference by substances in extracts of green oat shoots, can explain the inability of antibodies to recognize phytochrome isolated from green oat shoots. Immunopurified polyclonal rabbit antibodies to phytochrome from etiolated pea (Pisum sativum L.). shoots precipitate more than 95% of the photoreversible phytochrome obtained from etiolated pea shoots, while no more than 75% of the pigment is precipitated when phytochrome is isolated from green pea shoots. These data indicate in preliminary fashion that an immunochemically unique pool of phytochrome might also be present in extracts of green pea shoots.Abbreviation ELISA enzyme-linked immunosorbent assay - mU milliunit - Pfr far-red-absorbing form of phytochrome - Pr red-absorbing form of phytochrome     

Translocation of twinflower (Linnaea borealis L.) in the Scottish Borders

Summary

Twinflower, Linnaea borealis L., is a creeping, woody, clonal perennial nationally scarce in the UK, with its distribution confined to discrete patches in Scotland. Translocation of twinflower from natural patches into either existing patches, with a view to increasing genetic variation and outcrossing rates, or to unoccupied habitat, with a view to increasing its overall prevalence, could effectively increase the species' viability. In a small pilot experiment 38 shoots were moved from a vigorous patch in the Scottish Borders into two overtly hospitable clearings within the same woodland. Two years later 18 shoots (47%) survived and three years later four shoots (10.5%) remained, with die-back occurring irregularly over shoots of different initial lengths. No measured character of the original shoots explained which survived at each time interval. The most likely cause of the high mortality was competition from established grasses (Deschampsia flexuosa) which prevented growth and the formation of new roots along stolons. The study should help focus future efforts to determine best methods of increasing establishment of twinflower in Scotland.     

Notes on water relations of Polytrichum commune Hedw.

Abstract

Water loss in the endohydric moss Polytrichum commune was found to be controlled by a complex series of leaf arrangement changes, and by changes in water potential deficit of the shoots. This contrasted with the water relations of the ectohydric moss Rhacomitrium lanuginosum in which there was apparently little control over loss. Water conduction in Polytrichum was predominantly internal under high evaporative flux, and external under moderate flux, but under many stress conditions both pathways would probably be necessary to maintain an optimum water balance.     

Enzymic Phosphorylation of Some 5-Aminoimidazole Nucleosides to the 5′-Phosphates

Abstract

Phosphotransferases from wheat shoots and a suitable phosphate donor have been used for the specific conversion of unprotected pyrimidine and purine nucleosides and some analogues into nucleoside 5'-phosphates. We have been interested to investigate the application of this technique to the phosphorylation of 5-aminoimidazole nucleosides to afford corresponding 5'-phosphates related to intermediates in purine nucleotide de novo biosynthesis. Several D-ribofuranosyl, D-xylofuranosyl and D-arabinofuranosyl 5-aminoimidazoles have been successfully phosphorylated (TABLE) to 5'-phosphates using a phosphotransferase from wheat shoots and p-nitrophenylphosphate as a phosphate donor.     

The relation between the occurrence of polysety and the number of archegonia in female inflorescences of Dicranum majus and D. scoparium.

Abstract

Inflorescences of Dicranum scoparium contain 7–9 archegonia on average compared with 13–15 in D. majus. In D. majus polysety was observed in 55% of fertile shoots. There is no evidence that the occurrence of polysety in D. majus is associated with any increase in the number of archegonia. This was interpreted to show that all inflorescences contained four or five ripe archegonia at the time of fertilization. Since monosetous inflorescences were more common than polysetous ones, it was concluded that the supply of antherozoids was not saturating for fertilization. In D. scoparium polysety was observed in only 5% of fertile shoots.     

Effect of CPPU on in vitro axillary shoot proliferation and adventitious shoot regeneration in kiwifruit

Abstract

The effect of CPPU, N‐(2‐chloro‐4‐pyridyl)‐N‐phenylurea, on the development of axillary buds and on adventitious shoot regeneration was investigated in mature leaves of in vitro‐cultured shoots of Actinidia chinensis Planch (Sel. K190) and Actinidia deliciosa A. Chev. cultivars Hayward and Tomuri. In the multiplication phase, 2.2 mM CPPU induced proliferation rates comparable to 4.4 mM benzyadenine (BA) both in Hayward and in Tomuri, while a higher CPPU concentration reduced proliferation. In A. chinensis, significant differences in multiplication rates were not detected between BA and CPPU. However, shoots developed on CPPU appeared hyperhydric, and had very short internodes, reduced leaf laminas, higher water, carotenoid and phenol contents and considerably lower chlorophyll level in comparison with the BA‐grown shoots. On the other hand, in adventitious shoot regeneration CPPU was more effective than zeatin (ZEA) and BA in A. deliciousa cultivars and the best morphogenic response was obtained with the lowest concentration (10 mM) in cv Hayward, while 16 mM was the most efficient treatment in cv Tomuri. In A. chinensis, CPPU was as efficient as ZEA when the highest concentration was used.     

Effects of Trialkyltin Chlorides on Escherichia coli Spheroplasts

Valsa ceratosperma, which is the pathogenic fungus of apple canker, was grown in a synthetic medium. The neutral extract from the culture filtrate was chromatographed on a silica gel column to give five isocoumarins. Their structures were determined by MS, UV, IR, ¹H and ¹³C NMR, and CD spectra. Three of them were known compounds; ( ? )-5-methylmellein (1), ( ? )-5-carboxylmellein (2) and ( ? )-5-hydroxylmethylmellein (3). Since the absolute configurations at C-3 in 2 and 3 were not known until now, both were determined to be R by chemical correlations. The two were new compounds; ( + )-(3R,4S)-trans-4-hydroxy-5-methylmellein (4) and ( ? )-(3R,4R)-cis-4-hydroxy-5-methylmellein (5). All the five compounds showed phytotoxicity in a bioassay using detached apple shoots and lettuce seedlings.     

Investigation on the Physiological Ecology of Tortula ruraliformis

Abstract

1. Tortula ruraliformis is a xerophyte whose structura1 and physiological features suit it to an environment subject to cosiderable desiccation and sand movement

2. Untwisting and expansion of the leaves depend on hygroscopic movements but turgor phenomena may also be concerned.

3. The moss is poikilobydrous, its water content quickly equilibrating with the environment. The leaves unfold at relative humidities pater than 90 %.

4. The tops of the shoots are physiologically the most active. Analyses of the chief constituents (carbohydrates, nitrogen compounds. ash) have been made.

5. Sucrose is the most important photosynthetic product, making up usually S % or more of the dry weight of the plant. Starch is absent from the leaves, and most of the hexose is glucose.

6. Photosynthesis virtually ceases when the leaves are tightly rolled inwards round the stem.

7. On re-hydration of moderately drougbted shoots, the respiration rate rises quickly from a very low value, and the tissues can photosynthesize immediately.

8. After very prolonged desiccetion, photosynthetic power is impaired, and the respiration rises to a peak rate some appreciable time after re-hydration and then declines.     

Novae Gesneriaceae Neotropicarum XVI: Cremosperma anisophyllum, a new species of Gesneriaceae from the Chocó region of northern Ecuador and southern Colombia

A new species of Cremosperma (Gesneriaceae, tribe Beslerieae) is described from the Chocó floristic region of the western Andean slopes of northern Ecuador and southern Colombia. The dorsiventral shoots and strongly anisophyllous leaves differentiate Cremosperma anisophyllum from all other congeners.     

Rooting blockage in the tobacco rac mutant occurs at the initiation phase,and induces diversion to xylem differentiation

ABSTRACT

The rac mutant of Nicotiana tabacum L. cv. Xanthii is impaired in adventitious root formation. The objective of the present study was to determine whether or not the root induction phase occurs in the rac mutant, and if so, to determine what causes the induced cells to become incapable of organising root primordia. To this end, rac and wild-type shoots were cultured in vitro for 7 days under conditions suitable for obtaining roots in the wild-type (i.e., exposure to 5 µM indole-3-butyric acid for 4 h, and then transfer to hormone-free medium), and then histologically and biochemically analysed during culture. The variations in peroxidase activity, and in cellular levels of auxins and polyamines revealed that the induction phase occurs in rac shoots, although it lasts longer than in the wild-type ones. Furthermore, both auxin and polyamines were consistently higher in rac shoots compared to the wild-type. After induction, auxin and putrescine levels abruptly decreased in the wild-type shoots, whereas they decreased much more slowly in the rac mutant. The histological analysis of the wild-type shoots showed that the abrupt decrease in auxin and polyamine levels were correlated with a normal initiation phase. In fact, wild-type shoots showed cell divisions in the procambium already at day 2, resulting in the formation of root primordia at day 4, and in root emergence between days 5 and 7. In rac shoots, despite the fact that the procambium cells were activated to undergo cell division, the initiation phase was highly perturbed, and the procambial cells developed tracheary elements instead of adventitious roots. The different morphogenic responses of the two genotypes are discussed in the light of the differences in auxin content after the induction phase.     

Modified hormonal balance in rooting-recalcitrant rac mutant tobacco shoots

ABSTRACT

The rooting-recalcitrant rac tobacco mutant has been multiplied in vitro via outgrowth of axillary buds in parallel to the D8 wild-type. The mutant shoots grew at a lower rate and did not root whatever the treatments, whereas the wild-type shoots rooted spontaneously during the culture cycle without auxin treatment. The mutant and wild-type shoots showed similar peroxidase variations along the culture cycle (21 days) but with higher levels of activity for the rac mutant: minimum peroxidase activity occurred at day 14 in whole shoots of both tobacco genotypes, but already at day 7 in the basal parts of the stems (where roots appear) of the wild-type tobacco, while it was delayed in the mutant. Free and conjugated auxin and polyamine levels were also determined in whole shoots and basal parts of the stems. The rac mutant was characterised by higher auxin and polyamine contents. A peak of auxins and polyamines appeared at day 14 in the whole shoots whatever the tobacco genotype. This peak was delayed in the basal parts of the rac stems compared to the wild-type ones. The mutant shoots contained higher levels of benzyladenine and isopentenyladenosine at the end of the culture cycle, whereas zeatin riboside was more abundant in wild-type shoots. In response to increasing concentrations of indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA), only the wild-type shoots responded by an increase in growth rate followed by inhibition at high concentrations. The rac shoot responses were very low or nonexistent. Peroxidase activity was also measured in the basal parts of tobacco stems grown in the presence of IBA. Results suggest growth inhibition related to auxin accumulation, possibly combined with elevated putrescine content. Second, rooting induction seems to take place in both tobacco genotypes; however, the process of root formation is blocked in the mutant. The lack of initiation and expression phases of rooting in relation to auxin content in the mutant is discussed.     

Increased endogenous indole-3-acetic acid:abscisic acid ratio is a reliable marker of Pinus massoniana rejuvenation

ABSTRACT

Pinus massoniana is a recalcitrant tree species for rooting in vitro. We rejuvenated 26-year-old P. massoniana trees by successive grafting. Rooting rates of rejuvenated shoots were > 83.1% after rooting induction. We compared endogenous levels of indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellins (GAs) and zeatin-riboside (ZR), and the rhizogenesis ability of axillary shoots of mature and rejuvenated materials in vitro, i.e., somaplants and grafts. Enhancement of the rooting ability of mature materials in vitro following somatic embryogenesis or repeated grafting onto juvenile rootstocks was accompanied by increased IAA and GAs levels, and by decreased ABA levels in scions used as starting material for micropropagation in vitro. Successive subcultures did not influence the rooting ability of shoots from untreated mature material. Rooting ability of shoots in vitro, however, gradually increased with subculture frequency during repeated subculturing in grafting materials. The IAA:ABA ratio in shoots in vitro after grafting five times, and consequently capable of root organogenesis, was higher than in shoots of untreated mature material incapable of root organogenesis in vitro. A high IAA:ABA ratio was detected in scions of somaplants that were capable of rooting in vitro despite subculture times. We found that the endogenous IAA:ABA ratio is a reliable marker for the recovery of root organogenesis in vitro after rejuvenating treatments for mature P. massoniana trees.     

Phosphorylation of Some 5-Aminoimidazole Nucleosides to the 5’ -Phosphates Using a Phosphotransferase from Wheat

Abstract

Several D-ribofuranosyl, D-xylofuranosyl and D-arabinofuranosyl 5-aminoimidazoles have been successfully phosphorylated to 5’ -phosphates using a phosphotransferase from wheat shoots and p-nitrophenylphosphate as a phosphate donor.