David W. Fountain

Germination requirements of New Zealand native plants: a review

Abstract A review of our knowledge of the germination requirements of seeds of indigenous New Zealand plants is presented. A search of the literature reveals information, in varying detail, on only 113 species, some 5% of the estimated total of vascular plants, most of them from forest habitats. The New Zealand flora, much of it now endangered, represents a unique genetic resource. There is an urgent need for research in seed biology if this resource is to be conserved and maintained. Germination characteristics are tentatively assigned to the physiological groupings of vivipary, recalcitrance, quiescence, and dormancy. With regard to the latter, evidence is reviewed for the roles of light, low temperature, after-ripening, inhibitors, and seed-coat imposed dormancy.

Aerobiology and allergenicity of pinus radiata pollen in new zealand

Abstract An early Pinus season distinct from other airborne pollen grains is a feature of New Zealand pollen aerobiology. Its significance to health is uncertain as Pinus is generally considered not a potent allergenic pollen. Of proteins released by pollen of Pinus radiata upon hydration however, several IgE-binding species have been detected and incubation of human atopic IgE-rich serum with pollen extracts reduces subsequent IgE binding to ryegrass allergen RAST discs. The possibility of partial cross-allergenicity between Pinus and ryegrass is raised. In addition to proteins, low molecular weight compounds are also released by pine pollen. Amongst these are benzoic acid and 4-hydroxy benzoic acid. These substances, released in μg/g pollen quantities, are known to possess pharmacological activity and to adversely affect a low proportion of the population.

Observations on the leaf anatomy of Festuca novae‐zelandiae and biochemical responses to a water deficit

Abstract An examination using scanning electron microscopy, of the leaf anatomy of the New Zealand native tussock grass Festuca novae‐zelandiae, has been undertaken to highlight adaptations implicated in water‐deficit‐stress avoidance. The leaves are curled to form a tight cylinder enclosing a void region which is densely packed with trichomes. This region is continuous with the atmosphere via a narrow leaf margin gap, the aperture of which may be controlled by the relative turgidity of bulliform cells located between vascular ribs. Stomata are located only on the adaxial (inside) surface of the leaf. The leaves are fibrous because of the presence of numerous sclerenchyma (fibre) cells which, in the leaves examined, formed an almost continuous circle of bundles. When subjected to a water deficit, a preferential accumulation (compared on a per dry weight of tissue basis) of the osmoprotectant proline was observed in the leaf base, when compared with the immature or mature laminae. Conversely, the phy‐tohor...

FITC‐conjugated lectins as a tool for differentiating between toxic and non‐toxic marine dinoflagellates

Abstract FITC‐conjugated lectins proved to be effective probes for differentiating between morphologically similar dinoflagellate species isolated from New Zealand coastal waters. In particular the binding (fluorescence) of peanut (PNA) lectin differentiated G. mikimotoi from Gymnodinium sp. (Waimangu) and G. pulchellum and the non‐binding of Helix pomatia (HPA) and wheat germ (WGA) lectins discriminated between G. mikimotoi and the other Gymnodinium species tested. G. breve (Florida) was differentiated from the New Zealand isolates by binding with soy bean (SBA) lectin. Ulex europeus (UEA) distinguished the toxic species Alexandrium minutum from the morphologically similar, but non‐toxic, Cachonina hallii. Two strains of Prorocentrum lima (Spain and Rangaunu) were not differentiated by the lectins, but P. lima was differentiated from P. compressum.

A national survey of airborne pollen and grass flowering in New Zealand, with implications for respiratory disorder

Airborne pollen and spore levels were monitored at seven sites in New Zealand using the Intermittent Cycling Rotorod sampler during the summer of 1988/1989. Grasses formed the major component of atmospheric pollen levels during spring and summer at every locality. Peak levels of grass and total pollen occurred during December or late November, with a slight latitudinal lag apparent at the more southern sites. Highest levels were recorded at the smaller rural centres of Gore and Kaikohe and the lowest at the larger urban centres of Auckland, Christchurch and Wellington. We make a first approximation of the likely risk to hayfever and allergic asthma patients at each of the seven centres. For example, significantly higher grass pollen levels were experienced at Kaikohe on 44% and 65% of days during November and December, compared with just 15% and 8% at Auckland. By recording the flowering seasons of the principal allergenic grass species at each locality, we determined the potentially allergenic grasses contributing to peak pollen levels, the most ubiquitous being tall fescue (Festuca arundinacea Schreb.), ryegrass (Lolium perenne L.,L. multiflorum Lam.), cocksfoot (Dactylis glomerata L.), Yorkshire fog (Holcus lanatus L.) and sweet vernal (Anthoxanthum odoratum L.).

Seed development in Phaseolus vulgaris L. cv. Seminole. 3. NMR imaging of embryos during ethylene-induced precocious germination

Embryos taken from late maturation phase seeds of Phaseolus vulgaris cv. Seminole prior to seed desiccation (35–45 DAA) can be induced to germinate in the absence of water by exogenous ethylene. NMR imaging of proton relaxation within the embryo shows changes in water status in putative (and not fully differentiated) vascular tissues of the hypocotyl within 3 h of ethylene administration. Difference imaging revealed that the change was progressive in the hypocotyl towards the radicle tip and was accompanied by changes in water status in the cotyledons. Water within plumular leaves was also affected. Increase in diameter of the hypocotyl–radicle axis (as estimated by pixel counts) was detectable from 3 h. Longitudinal radicle growth was detectable by NMR imaging at 18 h. Visible germination under the conditions used was apparent after 20 h. Changes in water status detected by this technique are an indication of changes in activity (concentration) or motion of water molecules or both. The data are consistent with a mode of action of ethylene in stimulating a redistribution of water within embryo structures from cotyledons to axis via the cotyledonary node and allowing the axis access to water sufficient to support germination. This supports the hypothesis that in vivo , quiescence at this developmental stage is induced and maintained by sequestration of water within the cotyledons.

A lectin isolate from mucus of Helix aspersa

Abstract 1. 1. A lectin fraction has been isolated from mucus produced by the snail Helix aspersa by affinity chromatography of mucus protein on Sephadex G-100. The lectin is eluted with d -glucose. It agglutinates rabbit red blood cells but not human type A and is inhibited by d -GalNAc and to a lesser extent d -GlcNAc and d -Gal. 2. 2. The anti-A agglutinin of the Helix albumin gland was isolated by the same method and comparison of the two lectins by alkaline and acidic gel electrophoresis and by isoelectric focusing shows they are different. No cross-reactivity was apparent between the lectins to antiserum to the anti-A albumin lectin. 3. 3. By electrophoresis the mucus lectin isolate comprises 3 proteins, 2 of which are glycoprotein. At least 10 components are separated by isoelectric focusing. 4. 4. Mucus protein contains one dominant glycoprotein. The mucus lectin proteins account for the majority of the minor protein constituents of mucus protein.

Purification and characterization of a new lectin from tamarillo fruit (Cynhomandra betacea)

Abstract A new lectin (designated CBL1) from tamarillo fruit ( Cyphomandra betacea Sendt., Solanaceae) was identified and purified to apparent homogeneity by chitin affinity chromatography followed by ion-exchange chromatography. The molecular mass of CBL1 was 25 000 determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. CBL1 is an abundant, heat stable protein. Amino acid composition analysis showed abundant residues of Cys, Gly, Glx, Ser, Pro and Asx. Hydroxyproline residues were also present. The hemagglutination caused by CBL1 was most readily inhibited by N , N ′, N ″, N ‴-tetraacetylchitotetraose.

The lectin-like activity of Helix aspersa mucus

Abstract 1. 1. Helix mucus agglutinated rabbit red blood cells but not ox or human types A, B or O. Sheep cells were weakly agglutinated. The agglutination was inhibited by d -Ga1NAc and to a lesser extent d -GlcNAc and d -Gal. 2. 2. The lectin-like activity was lost above 80°C. Treatment at 60°C raised the activity several-fold over levels exhibited between -20 and 50°C. 3. 3. The activity was reduced by treatment of mucus with trypsin or pronase. The activity is ascribed to a protein component of the mucus and expressed as a titre based on protein content. The titre of mucus from individual snails varied widely. 4. 4. Mucus activity was stable for periods of up to 6 months. The protein content also remained stable providing microorganism growth was inhibited. Contrary to a previous report, no proteolytic activity associated with mucus was detected. Rehydration of dry mucus restored activity. 5. 5. The lectin-like activity was not an expression of an α-galactosidase-lectin.

In vitro germination of the trinucleate pollen of Limonium perezii

Optimal conditions for in vitro germination and tube growth of Limonium perezii (Plumbaginaceae) pollen were established. Boric acid, calcium nitrate, casein hydrolysate and sucrose were all important medium components. A dialysis tubing & filter paper support combined with using polyethylene glycol as an osmoticum in the medium provided appropriate physical conditions for L. perezii pollen germination. An in vitro pollen germination rate of about 40% was achieved. The longest pollen tube observed was four times the pollen grain diameter. While prehydration did not improve L. perezii pollen germination percentage nor the final pollen tube length, temperature influenced both of these factors. The optimum temperature range for germination was between 15°C and 35°C but the optimum temperature for pollen tube length was in the range 20°C‐25°C.