Size and longevity of seed banks of alpine gentian (Gentiana nivalis L.)

Summary

The alpine gentian (Gentiana nivalis L.) is a mountain rarity found at only two localities in Britain. It is an annual, establishing anew from seed each year and so the size and persistence of its seed bank is important for survival. Seed bank size was measured in summer, before seeds were shed, by sampling from soils at two sites where the alpine gentian is common. As the seeds do not germinate readily in the laboratory, it was assumed that all apparently healthy seeds extracted from the soils were alive and viable. This assumption was corroborated when 95–97% of seeds buried experimentally for 9–12 years germinated after repeated applications of gibberellic acid solution over a period of 6 months.

Densities of naturally buried alpine gentian seeds at the two sites ranged from 1.3 to 6.8 × 10³ seeds m^-2 and they comprised a major component of the community seed bank, disproportionately greater than the abundance of parent plants in the vegetation. The half-life of experimentally buried seeds was estimated as 15 or 32 years, depending on depth of burial and soil type. The findings explain why alpine gentian numbers can recover quickly after a population crash and emphasise the importance of the seed bank to the species' long-term survival in the montane environment.     

Newly developed polymorphic microsatellite markers in Job's tears (Coix lacryma‐jobi L.)

A microsatellite‐enriched library of Job's tears (Coix lacryma‐jobi L. var. Ma‐yuen Stapf) was constructed using a modified biotin–streptavidin capture method. After screening, 17 polymorphic microsatellites were used for diversity analysis among 30 Job's tears accessions. The number of alleles ranged from one to five alleles per locus with an average of 2.8 alleles. Expected heterozygosity (H_E) and polymorphism information content (PIC) ranged from 0 to 0.676 and from 0 to 0.666, respectively. The newly developed microsatellite markers are expected to be very valuable tools for evaluation of genetic diversity among large germplasm collection of Job's tears present in our Korean Gene Bank.     

Expression of the polymeric Immunoglobulin Receptor (pIgR) in mucosal tissues of common carp (Cyprinus carpio L.)

The mucosal immune system seems to be an important defence mechanism for fish but the binding of IgM in mucosal organs is poorly described in fish. In this study the gene encoding the polymeric Immunoglobulin Receptor (pIgR) in carp has been isolated and sequenced from a liver cDNA-library and aligned with other species. The pIgR of carp consists of 2 Ig domains, a transmembrane and an intracellular region, together 327 amino acids. In situ hybridisations with sense and anti-sense DIG-labelled pIgR RNA probes were performed on liver, gut and skin of common carp (Cyprinus carpio L.) and in these organs only anti-sense probes were found to hybridise. In liver the majority of hepatocytes was stained around the nucleus. In gut and skin, staining could be detected around the nucleus of the epithelial cells, but in gut also a subpopulation of lymphoid cells was stained in epithelium and lamina propria. The specific in situ hybridisation of the epithelia and hepatocytes coincides with the in situ binding of FITC-labelled carp IgM to the same cells. RT-PCR results indicate the expression of the pIgR gene in all lymphoid organs of carp, but not in muscle. Macrophages/neutrophils enriched by adherence or sorted B cells (MACS) did not show expression of the pIgR gene and are excluded as the pIgR expressing lymphoid cells in the intestine. The relevance of pIgR staining and gene expression in mucosal organs is discussed.     

Embryo rescue and plant regeneration in vitro of selfed chickpea (Cicer arietinum L.) and its wild annual relatives

The main constraint to the transfer of desired traits into cultivated chickpea from wild Cicer relatives is the presence of post-zygotic barriers which result in abortion of the immature embryo following interspecific hybridisation. Rescue of hybrid embryos in vitro and regeneration of hybrid plantlets could allow chickpea breeders to transfer desirable traits from wild relatives of chickpea. The development of embryo rescue techniques using selfed chickpea and selfed wild relatives is being used as a first step to protocols for wide hybrids. Optical microscopy studies of embryogenesis, in both selfs and hybrids, identified deleterious changes in the fertilised hybrid seed as early as 2–4 days after pollination in some crosses. These observations suggest that the appropriate time to rescue chickpea × C. bijugum hybrids is at the early globular stage of embryogenesis (2–7 days old), which requires the development of a complex tissue culture medium. In contrast hybrids between chickpea × C. pinnatifidum abort later (up to 15–20 days old) at the heart-shaped or torpedo stages, and are easier to rescue in vitro. Genotype also plays a significant role in the ability of immature selfed ovules to germinate in vitro. In this paper we report on the optimisation of␣protocols for rescueing immature embryos using selfed chickpea and its wild relatives in ovule, and subsequently to regenerate plantlets.     

Growth promotion of bean (Phaseolus vulgaris L.) by a polyamine-producing isolate of Streptomyces griseoluteus

Of seventy-five actinomycetes isolated from a bean rhizosphere in the United Arab Emirates, an isolate of Streptomyces griseoluteus (WT) was found to be capable of producing relatively high levels of putrescine on decarboxylase agar medium and to produce putrescine, spermidine and spermine in liquid decarboxylase medium. In the glasshouse, the application of the WT strain to soil amended with arginine (as a precursor for putrescine) significantly (P < 0.05) promoted the growth of bean plants and increased the fresh and dry weights and lengths of roots and shoots, compared with control plants. Infestation of soil with the WT strain resulted in a significant (P < 0.05) increase in the levels of putrescine, spermidine and spermine, certain endogenous plant growth regulators (PGRs) (indole-acetic acid, and gibberellic acid), chlorophylls (a, b) and carotenoids with a concomitant reduction in the level of abscisic acid in bean plants, compared with control plants. A polyamine non-producing mutant strain (PNPM) obtained from the wild-type isolate (WT), however, failed to promote plant growth. There were no significant (P > 0.05) differences between the levels of polyamines, endogenous PGRs, chlorophylls (a, b), and carotenoids between plants that were not exposed to either of the strain (control) and those grown in soil with the PNPM strain. Both WT and PNPM strains were incapable of producing in vitro detectable levels of PGRs, indole-acetic acid, indole-pyruvic acid, gibberellic acid, isopentenyl adenine and zeatin in the culture filtrates. This study is the first to demonstrate the potential of a polyamine-producing actinomycete to promote plant growth. In addition, it is also the first published report of the production of polyamines by streptomycete actinomycetes.     

Intergeneric somatic hybrids of rice [Oryza sativa L. (+) Porteresia coarctata (Roxb.) Tateoka]

Somatic hybrid plants were obtained following the electrofusion of rice (Oryza sativa L. cv ’Taipei 309’, 2n = 2x = 24) cell suspension–derived protoplasts with non-dividing leaf protoplasts of Porteresia coarctata (2n = 4x = 48), a saline-tolerant wild species. Fusion-treated protoplasts were plated on the surface of cellulose nitrate filter membranes, overlaying Lolium multiflorum nurse cells. The nurse cells were embedded in KPR medium containing 0.5 mg l⁻¹ 2,4–dichlorophenoxyacetic acid and semi-solidified with SeaPlaque agarose. Putative somatic hybrid cell colonies were selected on the basis of their growth, whereby faster growing colonies were transferred preferentially to MS-based medium with 2.0 mg l⁻¹ kinetin, 0.5 mg l⁻¹α-naphthaleneacetic acid, 30 g l⁻¹ sucrose and 4.0 g l⁻¹ SeaKem agarose to induce shoot regeneration. One hundred and nineteen regenerated plants were micropropagated clonally on MS-based medium containing 2.0 mg l⁻¹ 6–benzylaminopurine, 50 g l⁻¹ sucrose and 4.0 g l⁻¹ SeaKem agarose, prior to DNA extraction of plant samples. Putative somatic hybrids were initially identified by RAPD analysis, and 8 plant lines were selected for further investigation by flow cytometric ploidy determination and cytology. Plants of one line had an allohexaploid chromosome complement (2n = 6x = 72) and, following examination of its vegetative clones by GISH, were confirmed as somatic hybrids containing full chromosome complements of both O. sativa and P. coarctata. Received: 27 July 1998 / Accepted: 19 December 1998     

Swarmer release and distribution of life-cycle phases of Enteromorpha intestinalis (L.) (Chlorophyta) in relation to environmental factors

The percentage of reproductively mature fronds and swarmer production per frond were assessed daily (mid-summer) or bi-daily (fall and early winter) throughout an eulittoral bed of Enteromorpha intestinalis (L.) distributed along salinity and temperature gradients. Sporophytes were found throughout the eulittoral zone under a wide range of environmental conditions. Gametophytes were not observed in the high eulittoral and were rare (2% of all fronds) in the mid-eulittoral subject to reduced salinities (≈ 20.0%.). Where the low eulittoral was subject to marked changes in salinity, gametophyte frequency was higher (14.7%). Where salinity was constantly high (31.0%.) or where fronds were constantly immersed in moderately saline water (23.0%.), nearly half of the fronds were gametophytes. Frequency of reproductive fronds varied markedly between summer (65.7%) and fall-winter (38.9%) and with location in the bed (29.1 vs. 53.1%); frequency of fecund gametophytes did not vary seasonally.

Swarmer discharge per frond varied inversely with height on shore and was greater by 66% during summer than during fall-winter. Reproductive gametophytes were not observed beyond mid-December. Reproductive sporophytes were not observed beyond this date in the mid-to-high eulittoral zone but persisted to the end of the study (5 January) in sheltered, low eulittoral sites and where sporophytes were constantly immersed.

Mean daily swarmer production per frond varied significantly (P 0.05), due to synchrony of gamete discharge, both within and between stations; zoospore discharge occurred daily throughout the bed. The peaks in daily swarmer discharge were not synchronous with the occurrence of spring tides, as reported elsewhere; possible reasons for this are discussed.     

Effect of eluent pH on the HPLC-UV analysis of hyperforin from St. John's Wort (Hypericum perforatum L.)

The effect of the pH of the mobile phase in HPLC analysis of hyperforin was investigated. Working with an extract of St. John's Wort (Hypericum perforatum L.) that is rich in hyperforin, significant differences were observed in conventional chromatograms depending on whether the mobile phase was acidic or alkaline. Chromatogram changes were paralleled by changes in the UV spectrum of the hyperforin peak. The structural changes in hyperforin occur in the chromatographic column itself, as has been confirmed by UV spectroscopy performed on a sample of purified hyperforin, which showed that the UV spectrum is indeed dependent on the pH of its environment.     

Studies on the relationship between ploidy level,morphology, the concentration of some phytohormones and the nicotine concentration of haploid and doubled haploid tobacco (Nicotiana tabacum L.) and NICA plants

As compared to doubled haploid plants of the same origin, haploid tobacco plants are characterized by narrow leaves and in these leaves the endogenous concentration of gibberellins was considerably higher than in doubled haploids. This higher GA activity is almost entirely due to elevated levels of polar gibberellins. The same leaf shape as in haploids could be induced by GA₃ sprays to doubled haploids. A similar leaf shape was also observed on tissue culture derived so called NICA plants displaying the morphology of tobacco plants as described by Dudits et al. (1987) from whom the plant material was obtained as a gift. Here, in the leaves of a special strain with narrow lamina again a much higher gibberellin activity was detected than in the leaves of plants of the original tobacco strain. Histochemical determination of the relative DNA content indicated that leaves of NICA were chimaeras containing 1C cells besides cells with higher C values. Obviously, haploidy is somehow related to the endogenous gibberellin activity in tobacco plant material with consequences on the morphological appearance of 1n plants. Comparing some haploid and doubled haploid strains in tissue culture and pot and field experiments in several years apparently the genotype of the plant material is more significant for nicotine concentration than the ploidy level.Abbreviations DW dry weight - FW fresh weight - LSI leaf shape index     

Analysis of a pioneer community of Dittrichia viscosa (L.) Greuter in a mediterranean environment in southern Italy

Abstract

A pioneer community dominated by Dittrichia viscosa (L.) Greuter in a Mediterranean environment in southern Italy is described from a floristic point of view. Three main aspects are defined in a ploughed area in relation to substrate and soil depth. The pioneer role of D. viscosa is discussed in relation to its occurrence limited to below-ground disturbance.     

Response of two peanut (Arachis hypogaea L.) cultivars to boron and calcium

The response of two peanut cultivars (Tainan 9 and SK 38) to applications of six boron (B) rates (H₃BO₃ at 0, 0.12, 0.25, 0.5, 1 and 2 kg B ha^–1) at two calcium levels [nil (-Ca) or CaSO₄ at 100 kg Ca ha^–1 (+Ca)] to a B-deficient Oxic Paleustult was studied in a pot experiment. Without added Ca, both cultivars had low seed yields and gave only small responses to B. Similarly, without added B, both cultivars had low seed yields and did not respond to Ca. But, with added Ca or B, they responded strongly to B and Ca, respectively. In both cultivars, deficiencies of Ca or B depressed seed dry weight by depressing seed size by over 75%. Boron deficiency further depressed seed dry weight by decreasing the number of seeds per plant by decreasing the number of seeds per pod in Tainan 9, and the number of pods per plant in SK 38. Seed dry weight was depressed more than pod dry weight, so that both Ca and B deficiencies severely depressed the shelling %. With added Ca, tainan 9 responded to lower levels of B than SK 38, reaching maximum seed dry weight at 0.12 kg B ha^–1. At this low level of B. SK 38 yielded only half the seed dry weight of Tainan 9. But SK 38 continued to respond to increasing levels of B to 2 kg ha^–1, producing a maximum seed yield 40% higher than Tainan 9. The results indicate that where all other nutrients are adequate, SK 38 will yield better than Tainan 9 on soils with high B, but worse on soils with low B. The implications of these findings for the selection of peanut cultivars are discussed.     

Production of dodecaploid plants of Japanese persimmon (Diospyros kaki L.) by colchicine treatment of protoplasts

Summary Dodecaploid plants of Japanese persimmon (Diospyros kaki L.) were obtained by colchicine treatment of protoplasts. Callus protoplasts of Jiro (2n=90, x=15) were cultured in modified KM8p medium with 0.1% colchicine for 3–9 days. After colchicine treatment, they were cultured using agarose bead culture. Microcalli were recovered from the protoplasts after 3 months. Flow cytometric measurement showed that nine of 31 callus lines obtained from 6 days of colchicine treatment had twice the nuclear DNA content as non-treated controls. Plantlets were regenerated from the calli with twice the nuclear DNA content. Microscopic observation of root tip cells showed that their somatic chromosome number was 2n=180 (x=15). Compared with Jiro, dodecaploid plants had longer stomatal guard cells and lower stomatal densities, consistent with increased ploidy.     

Pollen morphology in the genus Veronica L. (Plantaginaceae) and its systematic significance

Pollen grains of 30, mainly annual, species from 134 populations of the genus Veronica (Plantaginaceae, formerly Scrophulariaceae) from the Mediterranean Region, have been studied with light and scanning electron microscopy. Three pollen types are defined based on pollen size and exine surface sculpture. In some cases within the study group pollen size can be useful in species determination. Hypothetical relationships of pollen grain size and aperture number with ploidy level, style length and corolla diameter are discussed. The ornamentation of the exine in Veronica, although generally a conservative character within the genus, gives some additional support to the most recent infrageneric classification of Veronica.     

Hemoglobin (Erythrogen™)-enhanced mitotic division and plant regeneration from cultured rice protoplasts (Oryza sativa L.)

Supplementation of culture medium with hemoglobin solution (Erythrogen™) promoted mitotic division, cell colony formation, and plant regeneration from rice (Oryza sativa L. cv. Taipei 309) protoplasts. The mean (± s.e.m., N = 5) final protoplast plating efficiency (FPE) at 28 days following exposure to 1:50 (v:v) Erythrogen™ (0.55 ± 0.06%) was significantly greater (P < 0.01) than in untreated controls (0.26 ± 0.02%). A similar, but less pronounced effect (P < 0.01) also occurred with 1:100 (v:v) (PE 0.53 ± 0.04%) and 1:500 (v:v) (PE 0.46 ± 0.05%) Erythrogen™, respectively. In contrast, there was no corresponding increase in plating efficiency with Erythrogen™ at 1:1,000 (v:v). These beneficial effects were sustained throughout culture. This leads to a 44% increase (P < 0.01) in protoplast-derived calli producing shoots compared to controls. Cytological analyses confirmed the diploid status of plants regenerated from Erythrogen™-treated and control protoplasts.     

Transpiration and canopy conductance in an inner alpine Scots pine (Pinus sylvestris L.) forest

Canopy transpiration (E_c) of a 150-year-old Pinus sylvestris L. stand in an inner Alpine dry valley, Tyrol, Austria was estimated throughout two growing seasons 2011 and 2012 by means of xylem sap flow measurements. Although there were prolonged periods of limited soil water availability, E_c did not show a clear trend with respect to soil water availability and averaged 0.4 ± 0.19 mm day⁻¹ under conditions of non-limiting soil water availability and 0.37 ± 0.17 mm day⁻¹ when soil water availability was limited. This is because canopy conductance declined significantly with increasing evaporative demand and thus significantly reduced tree water loss. The growing season total of E_c was 74 mm and 88 mm in 2011 and 2012, respectively, which is significantly below the values estimated for other P. sylvestris forest ecosystems in Central Europe, and thus reflecting a strong adaptation to soil drought during periods of high evaporative demands.