AJOL: South African Journal of Botany: VOLUME 69 ISSUE 2 (2003) Abstracts

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VOLUME 69 ISSUE 2 (2003)
ABSTRACTS

South African Journal of Botany 2002, 69: 117–128

Genetic and epigenetic aspects of somaclonal variation: flower colour bud

sports in azalea, a case study

S de Schepper¹*, P Debergh¹, E van Bockstaele¹, M de Loose², A Gerats³ and A Depicker⁴

¹ Department of Plant Production, Ghent University, Coupure Links 653, 9000 Ghent, Belgium

² Department of Plant Genetics and Breeding, Centre of Agricultural Research-Gent, Caritasstraat 21, 9090 Melle, Belgium

³ Katholieke Universiteit Nijmegen, Postbus 9102, 6500 HC Nijmegen, The Netherlands

⁴ Department of Molecular Genetics, Ghent University, K. Ledegankstraat 35, 9000 Gent, Belgium

Corresponding author, e-mail: [email protected]

Received 6 January 2003, accepted in revised form 27 January 2003

Bud sporting is the consequence of sudden variations in gene expression of somatic cells, leading to the occurrence of phenotypically altered shoots on plants. This phenomenon can be observed in most vegetatively propagated plant species and finds its origin in genetic as well as epigenetic events. In azalea the frequent occurrence of flower colour sports is appreciated as a valuable additional source of variation; more than half of the commercial assortment consists of flower colour bud sports. However, when clonal uniformity is desired for registration (Distinctness Uniformity Stability, DUS) and mass propagation, this somaclonal variation is perceived as a hindrance. Insight into the molecular mechanism(s) underlying the induction of bud sporting might improve breeding strategies, towards the appropriate choice of cultivars in hybridisation experiments. The complex beauty of sport phenotypes clearly indicates interactions within and between genetic and epigenetic mechanisms. Therefore, using azalea somaclonal variation as a model, a review of the literature on various genetic and epigenetic phenomena that regulate or influence gene expression, as well as on the links that exist between them is presented.

South African Journal of Botany 2002, 69: 129–134

Seasonal influence on vegetative growth and flower initiation of Spathiphyllum

L Heemers¹*, E Oyaert¹, MC van Labeke², E Volckaert² and P Debergh¹

¹ Department of Plant Production, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Coupure Links 653, B-9000 Gent, Belgium

² Research Center for Ornamental Plants, Schaessestraat 18, B-9070 Destelbergen, Belgium

Corresponding author, e-mail: [email protected]

Received 26 June 2002, accepted in revised form 7 October 2002

Vegetative growth and flower initiation of Spathiphyllum cultivars ‘Alfa’ and ‘Cervin’ were studied under various climatic conditions over a full year’s growth cycle. The four production cycles started respectively on 18^th March, 10th June, 10th September and 26th November 1998. These cycles are referred to as summer, autumn, winter and spring cultures respectively since the major part of the experimental period occurred in this specific season. This study indicated that ‘Alfa’ and ‘Cervin’ reacted in different ways during the year. Spathiphyllum ‘Alfa’ initiated flowers independently of the attained vegetative biomass and flower initiation occurred when growth rate was slow or decreased considerably. In the winter and spring cycles, ‘Alfa’ was able to initiate flowers in an early vegetative stage (12.4 leaves and 7.4 leaves respectively), whereas the summer and autumn cultured plants were larger (29.5 leaves and 23.2 leaves respectively) at the start of flower initiation. For ‘Alfa’, the absence of temperatures above 26°C seemed to be an initial (essential) condition to start flower initiation. In addition to non-elevated temperatures, decreasing or low light intensities and shortening of the photoperiod were associated with the conversion from the vegetative to the generative stage. For Spathiphyllum ‘Cervin’, however, no linkage of climatic conditions and the start of generative development was observed. ‘Cervin’ required a more extensive vegetative development than ‘Alfa’ before flower initiation could take place. In any of the four culture cycles, flower initiation did not occur before the plants had formed approximately seven shoots and 24 leaves.

South African Journal of Botany 2002, 69: 135–143

Does irrigation influence the growth, yield and water use efficiency of the protea hybrid ‘Sylvia’ (Protea susannae X Protea eximia)?

P Mortimer¹, JC Swart¹, AJ Valentine¹, G Jacobs² and MD Cramer¹*

¹ Department of Botany and Institute of Plant Biotechnology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa

² Department Horticultural Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa

Corresponding author, e-mail: [email protected]

Received 29 July 2002, accepted in revised form 14 October 2002

The response of the protea hybrid ‘Sylvia’ (Protea susannae X Protea eximia) to irrigation was investigated to determine the water requirements of this commercial floriculture crop. Both field and glasshouse trials were conducted in which plants were exposed to different irrigation levels. The effects of the irrigation regimes were determined by measuring the δ¹³C, δ¹⁵N, gas exchange characteristics, biomass accumulation, yield and root development. The plants in the glasshouse were exposed to watering regimes maintaining water at 20%, 40% and 60% of field capacity in sand-filled pots. Higher water supply resulted in increased growth of the roots in particular, but also of the shoots, reaching a maximum at 40% of field capacity. There were no significant changes in the gas exchange characteristics of the plants associated with this increased growth. In the field trial the intensity of irrigation (dry-land, normal and double-irrigation) did not influence the vegetative or reproductive biomass accumulation. Although the water content of the upper 30cm of soil was significantly different between treatments, there were no differences in δ¹³C, relative water contents or in elemental compositions of the leaves. The gas exchange characteristics of the plants were only slightly influenced by the irrigation intensity maintaining very similar water use efficiencies between treatments, concurring with δ¹³C results. However, the development of cluster roots was strongly increased by irrigation. Dryland plants had extensive sinker roots penetrating the deeper (>1m) soil layers. It was concluded that the dimorphic and deep roots of ‘Sylvia’ allow access to water deep in the soil profile once the root system is established. Although maintenance of cluster roots for nutrient uptake is important, management practices should take cognisance of the fact that surface soil water contents only partially determine the availability of water for these deep-rooted perennial shrubs, if at all.

South African Journal of Botany 2002, 69: 144–147

The ethnobotany and chemistry of the genus Clivia (Amaryllidaceae)

NR Crouch*¹,², DA Mulholland¹, TL Pohl¹ and E Ndlovu¹,³

¹ Natural Products Research Group, Department of Chemistry, University of Natal, Durban 4041, South Africa

² Ethnobotany Unit, National Botanical Institute, PO Box 52099, Berea Road 4007, South Africa

³ Kwamalulekoes Nursery and Herbalist, PO Box 11409, Mooi River 3300, South Africa

Corresponding author, e-mail: [email protected]

Received 4 June 2002, accepted in revised form 16 October 2002

The herbaceous genus Clivia Lindl. (Amaryllidaceae) comprises four species, all of which are employed in traditional medicine. Two lesser-known ethnomedicinal members, C. gardenii Hook. and C. caulescens R.A.Dyer are phytochemically characterised, revealing a variety of isoquinoline alkaloids. Hippeastrine, haemanthamine, (11S)-11-hydroxyvittatine, lycorine and sterbergine were isolated from C. caulescens, and haemanthamine, haemanthidine in its free base and quaternary salt form, and the quaternary salt of tazettine from C. gardenii. The traditional use of the genus Clivia in southern Africa is overviewed.

South African Journal of Botany 2002, 69: 148–150

Change in mistbelt mixed Podocarpus forest area between 1944 and 1996 in the Midmar catchment of KwaZulu-Natal, South Africa

NA Rivers-Moore*, JE Granger and F Ahmed

School of Applied Environmental Sciences, University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa

Corresponding author, email: [email protected]

Received 2 May 2002, accepted in revised form 31 October 2002

KwaZulu-Natal mistbelt (Podocarpus) forests serve as sources of firewood, structural timber, traditional food and medicinal products. Of the 3 694km2 of these forests in KwaZulu-Natal, only 0.45% is conserved. The extent of patches of Podocarpus forest in 1944 and 1996 within the Midmar catchment, KwaZulu-Natal, South Africa, were mapped from aerial photographs, and compared using a geographical information system. Overall, the area of Podocarpus forest was found to have increased from 784ha to 804ha between 1944 and 1996, as did mean patch area (km2), although not significantly. Interestingly, between 1944 and 1996, the number of forest patches decreased by 50%, with many smaller patches present in 1944 having disappeared by 1996. The implications of fragmentation of patches are discussed. Linking of forest patches with corridors of grassland, and further studies on the species composition of these forest patches, is suggested.

South African Journal of Botany 2002, 69: 151–157

Fruit anatomy of the genus Bupleurum (Apiaceae) in northeastern China and notes on systematic implications

M (Rebecca) Liu¹, L Shi², B-E van Wyk¹ and PM Tilney¹*

¹ Department of Botany, Rand Afrikaans University, PO Box 524, Auckland Park, Johannesburg 2006, South Africa

² The Beijing Botanical Garden, Institute of Botany, The Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China

Corresponding author, e-mail: [email protected]

Received 25 June 2002, accepted in revised form 7 November 2002

The fruit anatomy of all eight species of the genus Bupleurum L. mentioned in the most recent literature from northeastern China was studied for the first time. The eight species were divided into two groups based on the shape of the mericarps in transverse section. The first group (round mericarps without prominent ribs) includes B. longiradiatum and B. komarovianum, and the second group (angular mericarps with prominent ribs) includes B. angustissimum, B. bicaule, B. chinense, B. euphorbioides, B. scorzonerifolium and B. sibiricum. The second group can be further subdivided into group 2a (large vittae, very small vascular bundles) — B. euphorbioides and B. sibiricum, and group 2b (small vittae, large vascular bundles) — B. angustissimum, B. bicaule, B. chinense and B. scorzonerifolium. This result closely supports the traditional classification system which was based on gross morphology (plant height; leaf shape and size; involucre number, size and shape). The only exception is that B. komarovianum should not be close to the second group, but close to B. longiradiatum. Group 1 corresponds with Bupleurum sect. Longifolia and group 2 with sect. Eubupleura; group 2a with ser. Ranunculoides and group 2b with ser. Falcata. Fruit anatomical characters seem to have potential for evaluating infrageneric relationships in the genus Bupleurum.

South African Journal of Botany 2002, 69: 158–160

Bioactive sesquiterpene lactones isolated from the shoots of Arctotis arctotoides

N Sultana and AJ Afolayan

Department of Botany, University of Fort Hare, Alice 5700, South Africa

Corresponding author, e-mail: [email protected]

Received 12 September 2002, accepted in revised form 14 November 2002

Arctotis arctotoides is a perennial herb used medicinally for the treatment of various ailments in the Eastern Cape, South Africa. The n-hexane extract from the shoots of the herb showed antimicrobial activity against Bacillus subtilis. Bioassay guided fractionation of the extract has led to the isolation of two known sesquiterpene lactones, 4β, 15-dihydro-3-dehydro-zaluzanin C and dehydrobrachylaenolide. The structures of the compounds were elucidated by extensive use of 1Dand 2D-NMR (1H-1H COSY, HMQC, HMBC) studies. The antibacterial activity of the two compounds was demonstrated using bioautographic assay on TLC plates. The two compounds showed significant antibacterial activity against Bacillus subtilis, a Gram-positive bacterium.

South African Journal of Botany 2002, 69: 161–164

Lycium gariepense (Solanaceae), a new species from South Africa and Namibia

Andor M Venter* and HJT Venter

Department of Plant Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa

Corresponding author, e-mail: [email protected]

Received 29 August 2002, accepted in revised form 25 November 2002

Lycium gariepense, a new species from South Africa and Namibia, is described and figured. Its centre of dispersal seems to be the lower Orange River Valley of the Richtersveld and south-western Namibia. The new species is characterised by a functionally dioecious habit, feathery appearance, intricately branched and spreading growth form, much-branched, needle-like thorns, and flowers in which the staminal anthers are included in the corolla tube or protrude only slightly from the corolla mouth. This new species resembles L. bosciifolium Schinz and L. horridum Thunb.

South African Journal of Botany 2002, 69: 165–169

The suitability of Thin Layer Chromatography for authenticating bark medicines used in South African traditional healthcare

OM Grace¹, HDV Prendergast², J van Staden¹* and AK Jäger¹

¹ Research Centre for Plant Growth and Development, School of Botany and Zoology, University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa

² Centre for Economic Botany, Royal Botanic Gardens, Kew, Surrey TW9 3AE, United Kingdom

Corresponding author, email: [email protected]

Received 17 September 2002, accepted in revised form 26 November 2002

Thin Layer Chromatography (TLC) was investigated as a potential tool with which medicinal bark products used in South African traditional healthcare may be authenticated. Dried bark products are difficult to identify, and misidentification or adulteration increasingly affect their appropriate use and accurate documentation of their trade. A traditional medical practitioner pinpointed eight bark species used in KwaZulu-Natal, South Africa, that are difficult to identify. These were Ekebergia capensis (Meliaceae), Harpephyllum caffrum (Anacardiaceae), Rapanea melanophloeos (Myrsinaceae), Schotia brachypetala (Caesalpiniaceae), Croton sylvaticus (Euphorbiaceae), Albizia adianthifolia, Acacia sieberiana and Acacia xanthophloea (Mimosaceae). Three reference bark samples of each species were extracted in ethanol or hexane, separated on silica gel in petroleum spirit : ethyl acetate : chloroform : formic acid (8:7:5:1), and treated with anisaldehyde or vanillin reagents. TLC proved useful for showing similarities in the phytochemical fingerprints of a single species, but less so in distinguishing between the phytochemical fingerprints of different species. The technique assisted in confirming the identity of several medicinal bark products.

South African Journal of Botany 2002, 69: 170–175

Vegetative propagation of the threatened East African yellowwood (Podocarpus falcatus)

L Negash

Department of Biology, Faculty of Science, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia

e-mail: [email protected]

Received 30 September 2002, accepted in revised form 12 December 2002

Rooting in Podocarpus falcatus (Thunb.) Mirb. (syn. P. gracilior Pilg.) was studied using branch cuttings and whole seedlings harvested from 3-month-old, 2-yearold, 4-year-old and 8-year-old stockplants. The study was conducted in two separate propagators (two blocks) in which six different IBA treatments, viz. 0µg, 20µg, 40µg, 80µg, 160µg or 320µg IBA/cutting were administered to each of the 50–60 cuttings per treatment. The study found that cuttings from 3-month-old and 2-year-old stockplants responded well to IBA dosages between 20µg and 80µg/cutting, but were inhibited at higher concentrations. Treatments higher than 40µg/cutting significantly (P < 0.01) inhibited rooting in cuttings derived from the 4-year-old and 8-yearold stockplants. Rooting was significantly (P < 0.01) better in cuttings derived from 3-month-old and 2-year-old stockplants than from 4-year-old and 8-year-old stockplants. Indolebutyric acid significantly (P < 0.01) shortened the time taken for 50% rooting-response in cuttings derived from 3-month-old and 2-year-old stockplants. Notwithstanding the poor rooting response, cuttings derived from 4-year-old and 8-year-old stockplants produced far more roots per cutting than those from 3-month-old and 2-year-old stockplants. Stecklings (plants derived from rooted cuttings) grew significantly (P < 0.01) faster than seedlings, but plagiotropism in theformer remained a persistent problem.

South African Journal of Botany 2002, 69: 176–185

Somatic embryos of Picea abies behave like isolated zygotic embryos in vitro but with greatly reduced physiological vigour

CH Bornman1, OSP Dickens¹, CF van der Merwe², J Coetzee² and A-M Botha¹*

¹ Department of Genetics, Forestry and Agricultural Biotechnology Institute and ² Laboratory for Microscopy and Microanalysis, University of Pretoria, Pretoria 0002, South Africa

Corresponding author, e-mail: [email protected]

Received 15 January 2003, accepted 17 January 2003

Use of somatic or synthetic seed is of potential interest as a micropropagation tool for superior conifer genotypes. However, whether naked or encapsulated, the most important criterion is that the asexual embryo or somatic seed must be able to simulate the zygotic embryo or true seed. This study attempted a comparison of the somatic embryo of Norway spruce (Picea abies) with its zygotic counterpart. A major finding was that the percentage germination of fresh or somatic embryos partially desiccated at relative humidities of 97% and 63% to moisture contents approaching those of the seed, was substantially lower. It further declined rapidly with either cold storage and/or encapsulation. This sensitivity to drying suggests that the somatic embryo/seed may behave either as an orthodox seed with limited ability to withstand desiccation or as a recalcitrant seed that cannot survive drying below a moisture content that is relatively high. As the megagametophyte contains >80% of the seed’s total lipid and protein reserves, the carbon and amino acid pools available to the zygotic embryo far exceed those accessible to the somatic embryo. The conclusions are: (1) in Norway spruce the somatic seed, lacking a suitable artificial megagametophyte, does not simulate the true seed, and (2) the somatic embryo, if it behaves like an isolated zygotic embryo cultured in vitro, does so with greatly reduced physiological vigour.

South African Journal of Botany 2002, 69: 186–192

Growth inhibition of plant pathogenic bacteria and fungi by extracts from selected South African plant species

JC Pretorius¹*, S Magama¹ and PC Zietsman²

¹ University of the Free State, Department of Agronomy, PO Box 339, Bloemfontein 9300, South Africa

² National Museum, PO Box 266, Bloemfontein 9300, South Africa

Corresponding author, e-mail: [email protected]

Received 2 April 2002, accepted in revised form 3 February 2003

Extracts from 26 plant species representing 16 families, collected in the Free State Province of South Africa, were tested in vitro for their potential to inhibit the growth of eight plant pathogenic fungi and five plant pathogenic bacteria. None of the crude extracts showed any mycelial growth inhibition of the eight test fungi. All of the extracts inhibited the growth of one or more of the five plant pathogenic test bacteria, but to varying degrees. Crude extracts from Acacia karroo and Elephantorrhiza elephantina inhibited the growth of four bacteria, while that of Euclea crispa, Acacia erioloba, Senna italica and Buddleja saligna inhibited the growth of all five plant pathogenic bacteria. Of these, the crude extract of Euclea crispa was clearly superior to the rest as it compared more favourably to that of a commercial bactericide, Dimethyl Dodecyl Ammonium Chloride (DDAC). Subsequently, the Euclea crispa crude extract was fractionated by means of liquid-liquid extraction using four organic solvents, hexane, diethyl ether, chloroform and ethyl acetate, in order of increasing polarity. This was done in an attempt to assess the antimicrobial potential of the more concentrated fractions. Once again, none of the semi-purified fractions showed any antifungal activity. However, antibacterial activity was located in the more polar ethyl acetate fraction indicating that the substances involved were very similar in polarity and/or structure. From this it seems justified to further purify the ethyl acetate fraction of the Euclea crispa extract and attempt to identify the active substance(s) involved.

South African Journal of Botany 2002, 69: 193–198

Antimicrobial properties of extracts from Euclea crispa subsp. crispa (Ebenaceae) towards human pathogens

S Magama¹, JC Pretorius¹* and PC Zietsman²

¹Department of Soil-, Crop- and Climate Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa

²Bloemfontein National Museum, PO Box 266, Bloemfontein 9300, South Africa

Corresponding author, e-mail: [email protected]

Received 4 June 2002, accepted in revised form 3 February 2003

Leaf samples of Euclea crispa subsp. crispa were collected in the Bloemfontein area of the Free State Province as part of a project to screen South African plants for their antimicrobial potential. Crude extracts were obtained with a 95% methanol solution and the aqueous fraction remaining after methanol was removed by distillation, was bioassayed in vitro for its potential to inhibit the growth of eleven human pathogenic bacteria and two human pathogenic fungi. Of all the plant extracts tested, the E. crispa crude leaf extract showed the most promising antimicrobial activity against human pathogenic bacteria and fungi. Subsequently, the crude extract was fractionated by means of liquid-liquid extraction using four different organic solvents in order of increasing polarity. Most of the antibacterial activity was observed in the more polar ethyl acetate fraction. No particular trend of inhibition was observed between the Gram-negative and Grampositive bacteria. Neither the crude extract nor the semipurified fractions inhibited the growth of Haemophilus influenzae, Klebsiella pneumoniae and Streptococcus pneumoniae. The growth of the other eight human pathogenic bacteria was inhibited to different degrees. Both the crude extract as well as all the semi-purified fractions inhibited the growth of two human pathogenic test fungi.

South African Journal of Botany 2002, 69: 199–203

In vitro antibacterial activity of Venda medicinal plants

CL Obi*, N Potgieter, PO Bessong, T Masebe, H Mathebula and P Molobela

Department of Microbiology, University of Venda for Science and Technology, Thohoyandou, Private Bag X5050, Thohoyandou 0950, South Africa

Corresponding author, e-mail: [email protected] or [email protected]

Received 18 March 2002, accepted in revised form 8 October 2002

Ethanolic and aqueous extracts of ten medicinal plants used in folklore medicine in Venda (South Africa) were screened for their in vitro activity against some Grampositive and Gram-negative pathogenic bacteria using the disc diffusion method. Root and stembark extracts of Datura stramonium at a concentration of 50mg ml-1 were inhibitory to most of the organisms with a diameter of zone of inhibition of growth ranging from 12–19mm. Warburgia salutaris was also inhibitory to most of the bacteria with a diameter of zone of inhibition of growth ranging from 8–17mm at a concentration of 50mg ml-1. A range of 10–16mm was observed for Peltophorum africanum at a concentration of 40mg ml-1 against the Gram-negative bacteria tested. Other plants showed moderate or no activity, compared to a 30µg ml-1 oxytetracycline control antibiotic. The use of these plants by the indigenes of Venda against diseases apparently caused by these organisms may be of some value.

South African Journal of Botany 2002, 69: 204–206

Phylogenetic relationships of the recently discovered species — Clivia mirabilis

F Conrad1*, G Reeves1 and JP Rourke2

1 Leslie Hill Molecular Systematics Laboratory, National Botanical Institute, Private Bag X7, Claremont 7735, South Africa

2 Compton Herbarium, National Botanical Institute, Private Bag X7, Claremont 7735, South Africa

Corresponding author, email: [email protected]

Received 14 October 2002, accepted in revised form 13 January 2003

A phylogenetic study of Clivia, including the newly described species, Clivia mirabilis, recently discovered in the Northern Cape, was carried out to elucidate the relationship of this geographically isolated taxon to the remaining four species. DNA sequence data were collected from four non-coding plastid regions: the rpoBtrnC intergenic spacer, the rps16 intron, the trnL intron and the trnL-F intergenic spacer (the latter two collectively known as the trnL-F region). In the combined tree C. mirabilis is placed as sister to a clade comprising the other four taxa.

South African Journal of Botany 2002, 69: 207–211

Effect of a seaweed concentrate on the growth and yield of three varieties of Capsicum annuum

GD Arthur, WA Stirk* and J van Staden

Research Centre for Plant Growth and Development, School of Botany and Zoology, University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa

Corresponding author, e-mail: [email protected]

Received 29 October 2002, accepted in revised form 16 January 2003

The effect of different modes of application of Kelpak on the growth and yield of three varieties of greenhouse cultivated peppers was investigated. In most instances, application of Kelpak improved the marketable fruit yield. A combined treatment of dipping the seedlings in 0.4% Kelpak solution for 2h prior to transplanting followed by three applications of 0.4% Kelpak as a foliar spray during the growth of the plants significantly increased the number and size of the marketable fruit.

South African Journal of Botany 2002, 69: 212–213

Raphionacme (Apocynaceae: Periplocoideae): nomenclatural notes for southern African species

HJT Venter

Department of Plant Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa

e-mail: [email protected]

Received 29 August 2002, accepted in revised form 7 October 2002

Raphionacme Harv. is a genus of mostly geophytic herbaceous plants, numbering 37 species and, with the exception of one species, all endemic to Africa. In southern Africa (Botswana, Lesotho, Namibia, South Africa and Swaziland) a total of 16 species are recognized by the present author, although no less than 27 species and two varieties were described for Raphionacme in the region. Six species and two varietietal names are new synonyms for the region. These names are synonymised here.

South African Journal of Botany 2002, 69: 214–216

Tissue culture enhances the propagation potential of some Tillandsioideae

JC Chukwujekwu and J van Staden*

Research Centre for Plant Growth and Development, School of Botany and Zoology, University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa

Corresponding author, e-mail: [email protected]

Received 3 December 2002, accepted in revised form 9 December 2002

Seeds of three Tillandsia species were germinated in vitro and multiple shoots produced within 13 months in culture. Different Murashige and Skoog media; fullstrength, half-strength, and half-strength macro/full micro salts plus 25mg l-1 NaFeEDTA, were used for germination. For multiple shoots the best germination medium was used with different plant growth regulators added (0.5/0.5mg l-1 or 1.0/0.5mg l-1 BA/NAA).

South African Journal of Botany 2002, 69: 217–219

The nitric oxide specific scavenger carboxy-PTIO does not inhibit smoke stimulated germination of Grand Rapids lettuce seeds

ME Light and J van Staden*

Research Centre for Plant Growth and Development, School of Botany and Zoology, University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South Africa

Corresponding author, e-mail: [email protected]

Received 5 December 2002, accepted in revised form 13 January 2003

As part of a continued effort to understand the mechanism underlying smoke-stimulated seed germination, the effect of two nitric oxide (NO) donors N-tert-butyl-α-phenylnitrone (PBN) and sodium nitroprusside (SNP) on the germination of Grand Rapids lettuce seeds were investigated. Seeds were treated with solutions of PBN and SNP at concentrations from 10–1 000µm, and with a combination of 1:1 000 aqueous smoke solution and the NO specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium (c-PTIO). No enhanced germination was observed with the PBN and SNP treatments, and c-PTIO showed no inhibition of the germination stimulated by a 1:1 000 dilution of an aqueous smoke solution. These results suggest that factors, other than NO, are responsible for the enhanced germination of Grand Rapids lettuce seeds by aqueous smoke solutions.

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African Journals OnLine South African Journal of Botany

VOLUME 69 ISSUE 2 (2003) ABSTRACTS

Tissue culture enhances the propagation potential of some Tillandsioideae

African Journals OnLine
South African Journal of Botany

VOLUME 69 ISSUE 2 (2003)
ABSTRACTS