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Mbenoun M.,University of Pretoria | Wingfield M.J.,University of Pretoria | Letsoalo T.,University of Pretoria | Bihon W.,University of Pretoria | And 3 more authors.
Fungal Biology | Year: 2015

Thielaviopsis ethacetica was recently reinstated as a distinct taxon using DNA phylogenies. It is widespread affecting several crop plants of global economic importance. In this study, microsatellite markers were developed and used in conjunction with sequence data to investigate the genetic diversity and structure of Th. ethacetica in Cameroon. A collection of 71 isolates from cacao, oil palm, and pineapple, supplemented with nine isolates from other countries were analysed. Four genetic groups were identified. Two of these were associated with oil palm in Cameroon and showed high genetic diversity, suggesting that they might represent an indigenous population of the pathogen. In contrast, the remaining two groups, associated with cacao and pineapple, had low genetic diversity and, most likely, represent introduced populations. There was no evidence of gene flow between these groups. Phylogenetic analyses based on sequences of the tef1-α as well as the combined flanking regions of six microsatellite loci were consistent with population genetic analyses and suggested that Th. ethacetica is comprised of two divergent genetic lineages. © 2015 The British Mycological Society. Source


Matsaunyane L.B.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Matsaunyane L.B.,University of Johannesburg | Oelofse D.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Dubery I.A.,University of Johannesburg
BMC Research Notes | Year: 2015

Background: The Malus domestica polygalacturonase inhibiting protein 1 (MdPGIP1) gene, encoding the M. domestica polygalacturonase inhibiting protein 1 (MdPGIP1), was isolated from the Granny Smith apple cultivar (GenBank accession no. DQ185063). The gene was used to transform tobacco and potato for enhanced resistance against fungal diseases. Findings: Analysis of the MdPGIP1 nucleotide sequence revealed that the gene comprises 993 nucleotides that encode a 330 amino acid polypeptide. In silico characterization of the MdPGIP1 polypeptide revealed domains typical of PGIP proteins, which include a 24 amino acid putative signal peptide, a potential cleavage site [Alanine-Leucine-Serine (ALS)] for the signal peptide, a 238 amino acid leucine-rich repeat (LRR) domain, a 46 amino acid N-terminal domain and a 22 amino acid C-terminal domain. The hydropathic evaluation of MdPGIP1 indicated a repetitive hydrophobic motif in the LRR domain and a hydrophilic surface area consistent with a globular protein. The typical consensus glycosylation sequence of Asn-X-Ser/Thr was identified in MdPGIP1, indicating potential N-linked glycosylation of MdPGIP1. The molecular mass of non-glycosylated MdPGIP1 was calculated as 36.615 kDa and the theoretical isoelectric point as 6.98. Furthermore, the secondary and tertiary structure of MdPGIP1 was modelled, and revealed that MdPGIP1 is a curved and elongated molecule that contains sheet B1, sheet B2 and 310-helices on its LRR domain. Conclusion: The overall properties of the MdPGIP1 protein is similar to that of the prototypical Phaseolus vulgaris PGIP 2 (PvPGIP2), and the detected differences supported its use in biotechnological applications as an inhibitor of targeted fungal polygalacturonases (PGs). © 2015 Matsaunyane et al.; licensee BioMed Central. Source


Gazendam I.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Greyling R.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Laurie R.N.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Matsaunyane L.B.T.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Oelofse D.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI
Acta Horticulturae | Year: 2016

South Africa is classified as a water-stressed country. All technologies, including biotechnological tools, should therefore be utilized to assist in the protection of crops against adverse environmental conditions. A project was initiated in 2012 to create a more drought tolerant local potato cultivar using a transgenic approach. The StMYB1R-1 transcription factor (TF) gene was isolated from potato cultivar 'BP1' and subcloned into a plant transformation vector under constitutive (CaMV 35S) or inducible (rd29A) promoter control. Transgenic lines of potato 'BP1' with the different constructs were generated. The transgenic StMYB1R-1 gene was stably inserted into the potato genome. The highest expressing transgenic lines were selected with RT-qPCR, which also verified the inducible promoter behaviour under drought stress conditions. It is proposed that the transgenic TF gene will activate delayed response drought-protective genes and in turn render the potato plant more drought tolerant, since less water will be lost by the plant under water-stressed conditions. Relative water content (RWC%) results, visual appearance after 11 days of stress, and survival rates after the 15 d water-stress period of the first greenhouse trial, indicated that two transgenic potato lines, C3 and D6, performed better under drought conditions at 10 days without water (dwow) compared to 'BP1'. The RWC% results could not be confirmed in the second trial. None of the transgenic lines had statistically significantly higher biomass yields than 'BP1' under drought stressed greenhouse conditions. It can therefore not be concluded that the insertion of the StMYB1R-1 transgene improved the drought tolerance of any of these transgenic potato lines, compared to the non-transformed plants. Source


Mulabisana J.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Cloete M.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Mabasa K.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Laurie S.M.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | And 2 more authors.
Acta Horticulturae | Year: 2015

Sweetpotato is an important food crop in rural communities of South Africa due to its nutritional content, including β carotene (provitamin A) from the orangefleshed sweetpotato. Sweetpotato is also popular among farmers with limited resources, playing an important role as a food security crop. It is also grown commercially for the fresh and export markets. Potyviruses, such as Sweet potato feathery mottle virus (SPFMV) and a Geminivirus, Sweetpotato leaf curl virus (SPLCV), are threatening the production of sweetpotato in South Africa. NCM-ELISA and published reverse transcription polymerase chain reaction (RT-PCR) and PCR methods were used to detect SPFMV and SPLCV. The cloned coat protein genes of SPFMV [russet crack (RC) and common (C) strains)] and SPLCV were sequenced. RTPCR confirmed the occurrence of SPFMV, and distinguished between its different strains (RC and C) in samples collected from different provinces of South Africa. Sequencing and phylogenetic analysis also confirmed that both the RC and C strains of SPFMV are present, and could spread to other provinces of the country. The Geminivirus SPLCV isolates were also correctly identified, and are related to those reported in other parts of the world. Source


Maboko M.M.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Du Plooy C.P.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI | Chiloane S.,Agricultural Research Council Vegetable and Ornamental Plant Institute ARC VOPI
African Journal of Agricultural Research | Year: 2011

A study was conducted in 2009 to 2010 and 2010 to 2011 to investigate the effect of plant population, and fruit and stem pruning of hydroponically grown tomatoes in a 40% (black and white) shade-net structure at the ARC-Roodeplaat VOPI. An open bag hydroponic system containing sawdust as a growing medium was used in this experiment. Tomato plants were subjected to three plant populations (2, 2.5 or 3 plants/m 2), two stem pruning treatments (one stem and two stems) and three fruit pruning treatments (four fruits, six fruits per truss, and no fruit pruning). Experimental layout was a complete randomized block design with three replicates. Data on fruit number, fruit mass, unmarketable yield, marketable yield and total yield was collected from 10 plants for all treatments. Plants pruned to two stems with zero fruit pruning or pruned to six fruits produced significantly higher marketable and total yield, as compared to the other treatments. Plant population of 3 plants/m 2, resulted in significantly higher marketable yield of tomatoes, compared to 2.5 and 2 plants/m 2. Results showed that tomato yield and quality can be effectively manipulated by plant population and stem pruning, while fruit pruning had only a limited effect. ©2011 Academic Journals. Source

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