Mofokeng M.,Vegetable and Ornamental Plant Institute ARC VOPI |
Prinsloo G.,Vegetable and Ornamental Plant Institute ARC VOPI |
Kritzinger Q.,University of Pretoria
Seed Science and Technology | Year: 2012
Observation trials on seed germination of medicinal plant species of South Africa sometimes indicated erratic or low germination percentages (0-20%) attributed to seed dormancy. The aim of this research was to give a first report on the temperatures and treatments needed to obtain a high percentage of seed germination for four indigenous medicinal plant species, Alepidea amatymbica, Bowiea volubilis subsp. volubilis. Dicoma anomala subsp. anomala, and Leonotis ocymifolia var. raineriana. Germination, including additional treatments, like smoke treatment and removal of hair like structures on seeds, were investigated at temperatures ranging from 10°C to 30°C Smoke treated seeds of A. amatymbica germinated best (10%) at 25°C while D. anomala showed increased germination (68%) at 15°C after the removal of hair like structures. Germination of untreated seeds of L. ocymifolia was best at 20°C with a germination percentage of 78%. Untreated seeds of B. volubilis germinated at 15°C gave the highest germination percentage of 92%.
Matsaunyane L.B.T.,Vegetable and Ornamental Plant Institute ARC VOPI |
Matsaunyane L.B.T.,University of Johannesburg |
Oelofse D.,Vegetable and Ornamental Plant Institute ARC VOPI |
Dubery I.A.,University of Johannesburg
Potato Research | Year: 2016
Current safety assessment of genetically modified crops requires detailed information about the insertion of the transgene and the effect of its expression on the biochemistry and physiology of the host plant. Whilst the intended effect of the transformation can be verified through phenotypic screening, molecular approaches are required to observe unintended effects. We investigated the molecular details of the integration of a polygalacturonase inhibiting protein 1 gene from Malus domestica (Mdpgip1), overexpressed in Solanum tuberosum (cv BP1) for enhanced resistance against Verticillium wilt. Genome walking studies of the selected AppA6 transformant revealed that the T-DNA containing the Mdpgip1 transgene under control of the CaMV 35S promoter was inserted into the genome without any non-T-DNA sequences from the pCAMBIA2300 vector. Sequence data indicate that the insertion of the Mdpgip1 transgene was in a gene-rich region of chromosome 1, adjacent to the photosystem QB gene but without disruption of structural genes. Transcriptome-based cDNA-representational difference analysis revealed the distinctive expression of Mdpgip1 in the transgenic AppA6 line, verifying the intended effect. Protein extracts from the transgenic plants inhibited the activities of Verticillium dahliae polygalacturonases in in vitro studies, showing that the transgene is expressed to produce an active PGIP defense protein. cDNA-AFLP fingerprinting revealed genes that were differentially expressed, including genes encoding tryptophan/tyrosine permease, Ef-Tu domain and SKP1-like 1A proteins. qRT-PCR indicated that the Mdpgip1 transgene insertion resulted in increased expression in the AppA6 transgenic of the xyloglucan endotransglycosylase (xth) gene and an endogenous Stpgip1 gene. These unintended changes were either caused by the constitutive expression of the Mdpgip1 transgene or transformation-related somaclonal variation. The results indicate that the stable, single copy integration of the Mdpgip1 gene in the AppA6 transgenic line did not disrupt any structural genes but caused unintended effects that affected gene expression compared to the parental counterpart under the non-stressed experimental conditions investigated. © 2016 European Association for Potato Research
Kleynhans R.,Vegetable and Ornamental Plant Institute ARC VOPI
Acta Horticulturae | Year: 2013
Many of South Africa's medicinal plant species are declining in the wild, facing extinction due to over harvesting and poor regulation of these natural resources. Some of these species are also entering the commercial market, which demands large quantities of plant material. There are a limited number of South African medicinal plant species that are cultivated and information on cultivation is generally lacking or very scarce. Extensive research is taking place on the identification of medicinal compounds, testing of toxicology and efficacy, quality control and product development. However, the actual commercialization of products is reliant on a sustainable supply of quality material, which implies the production of plant material on a commercial scale. The ARC-Roodeplaat VOPI is thus conducting research to develop the relevant propagation and cultivation methods for medicinal plant species so as to address this phase in the value chain. The first step for successful commercial production is the propagation of sufficient material for harvesting. Both seed multiplication and vegetative production methods are being investigated. After establishing propagation methods, material has to be grown until harvesting of the specific plant parts. Cultivation methods, such as spacing, irrigation and fertilization play an important role in plant growth and production, and optimal production practices have to be developed for each species. The effect of these practices on the medicinal compounds and medicinal activity also needs constant monitoring. Throughout this process the financial aspect of production has to be taken into account to ensure that cultivation is financially viable. Finally, the ARC-Roodeplaat VOPI conducts training on medicinal plant propagation and transfers the developed technologies to communities, traditional practitioners and commercial entities to contribute towards the sustainable cultivation of medicinal plants. The Institute thus contributes towards medicinal plant research by fulfilling a specific niche in the complete value chain of medicinal plant research.
Bihon W.,Vegetable and Ornamental Plant Institute ARC VOPI |
Cloete M.,Vegetable and Ornamental Plant Institute ARC VOPI |
Gerrano A.,Vegetable and Ornamental Plant Institute ARC VOPI |
Adebola P.,Vegetable and Ornamental Plant Institute ARC VOPI |
Oelofse D.,Vegetable and Ornamental Plant Institute ARC VOPI
Plant Disease | Year: 2015
Onion (Allium cepa L.) is widely produced and the third most important vegetable crop in South Africa. During the onion-planting season in 2013, blight-like symptoms were observed on leaves of onion plants at the onion seed multiplication site of the Agricultural Research Council-Vegetable and Ornamental Plant Institute (ARC-VOPI). Diseased leaf samples were collected and fungi were isolated using potato dextrose agar (PDA, Difco Labs, Detroit, MI, USA) medium. Eleven single-spore isolates of pure fungal cultures were obtained. Preliminary species identifications were conducted based on size, color, and shape of conidia. Muriform, short-beaked, and golden-brown conidia emerged in chains with a length of 37 µm (23 to 81 µm), suggesting that four of the isolates collected were similar to Alternaria alternata (Fr.) Keissler (Woudenberg et al. 2013). To confirm the identity of these isolates, the internal transcribed spacer (ITS) region of ribosomal DNA, elongation factor-1 alpha gene (EF), and the RNA polymerase II second largest subunit (RPB2) gene were amplified with universal primers (Liu et al. 1999; O’Donnell et al. 1998; White et al. 1990). Amplicons were sequenced at Inqaba Biotechnology Industries, South Africa. Sequences of each of the ITS, EF1α, and RPB2 of each representative isolate were deposited into GenBank (Accession Nos. KP940475, KP940476, and KP940478, respectively). DNA of fungal isolates from onion were 99% identical to: ITS sequences of HQ130485 and HQ846574; and RPB2 sequences were 99 to 100% identical to KC584375, KJ443163, and DQ677980 of A. alternata. The EF sequences had 100% sequence similarity to A. alternata sequences from GenBank (EU139384 and KC584634). Pathogenicity tests were conducted in a greenhouse. Thirty onion seedlings were raised from surface-sterilized seeds. Of these plants, 20 were sprayed with a spore suspension (4 × 107 conidia/ml) with 0.1% Tween20, until most of the leaves were wet. Control treatments (10 plants) were sprayed with sterile distilled water. Three days after inoculation, all the infected and control plants were covered with a plastic sheet to increase humidity. Greenhouse conditions were maintained at a minimum/maximum temperature of 20/26°C. Three weeks after inoculation, blight lesions similar to symptoms observed in the field were found on inoculated plants, while the control treatments remained free of disease symptoms. Cultural characteristics of fungi reisolated from inoculated but not from control plants were consistent with A. alternata. A. alternata is one of the known fungal plant pathogens reported on a diversity of plants worldwide (Ramjegathesh et al. 2011; Woudenberg et al. 2013). To our knowledge, this is the first report from South Africa of this fungus being isolated from onion, suggesting a risk for onion industries in the region. © The American Phytopathological Society.