GENETICALLY MODIFIED COTTON IN SOUTH AFRICA: THE SOLUTION FOR RURAL DEVELOPMENT?

Community/Rural/Urban Development, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Diversity and abundance of flower-visiting insects in Bt and non-Bt cotton fields of Maputaland (KwaZulu Natal Province, South Africa)

International audienceWe studied the abundance and diversity of flower-visiting insects on Bt and non-Bt cotton plants in the Makhathini Flats region of South Africa during the 2003/2004 and 2004/2005 crop seasons to detect any impact of the Bt toxin (Cry1Ac). Bt cotton cultivars produced more flowers than non-Bt cultivars regardless of the cropping conditions (farmers' fields or research station), probably due to the fact that Bt cotton is not susceptible to flower bud pests. The results obtained in both crop seasons highlighted the prevalence of honeybees (Apis mellifera L.), various Nitidulidae and a unique Meloidae species (Mylabris oculata Thunberg) as flower visiting insects in this area. No impact of the Bt phenotype on insect abundance and diversity could be drawn on the basis of our comparative results on Bt and non-Bt cotton plants, and no direct effect of these transgenic plants was actually noted. The potential role of some of the inventoried insects, especially M. oculata, in the dispersal of transgenic pollen is discuss

Effect of water-deficit stress on cotton plants expressing the Bacillus thuringiensis toxin

Bacillus thuringiensis (Bt) crops require a high dosage of Bt toxin to delay development of insect resistance, in particular, when the refuge strategy is applied. This strategy is threatened by plant developmental and environmental factors that might reduce Bt toxin concentration and Bt efficacy in Bt crops. Growth of Bt (Cry1Ac) cotton under prolonged, moderate water deficit as a single stress factor was evaluated. Bt cotton plants were analysed for physiological performance, Bt toxin concentration and Bt efficacy. For performance analysis, leaf and total plant dry weight and leaf area were measured. Bt toxin concentration was determined by an immuno-assay. Effects of Bt toxin on growth and mortality of African cotton bollworm, Helicoverpa armigera, larvae were measured in different plant organs. Leaves from young plants exposed for 30 days to moderate water deficit had both higher Bt toxin concentrations and were more effective against larvae than leaves, flowers or bolls from mature flowering plants exposed to 60 days of moderate water deficit. Although growth of Bt cotton plants under moderate water-deficit conditions decreased Bt concentrations in leaves, flowers and bolls, this had no effect on efficacy against first-instar cotton bollworm larvae. No significant evidence was found that moderate water deficit, as a single stress factor, decreases Bt efficacy in Bt cotton

Assessment of gene flow between gossypium hirsutum and G. herbaceum : evidence of unreduced gametes in the diploid progenitor

In the framework of a gene flow assessment, we investigated the natural hybridization rate between Gossypium hirsutum (AADD genome) and G. herbaceum (AA genome). The latter species, a diploid progenitor of G. hirsutum, is spontaneously present in South Africa. Reciprocal crosses were performed without emasculation between G. herbaceum and G. hirsutum. Neither examination of the morphological characteristics nor flow cytometry analysis of the 335 plants resulting from the G. hirsutum · G. herbaceum cross showed any hybrid features. Of the 148 plants produced from the G. herbaceum · G. hirsutum cross, three showed a hybrid phenotype, and their hybrid status was confirmed by SSR markers. Analysis of DNA content by flow cytometry and morphological traits clearly showed that two of these plants were triploid (AAD). The third plant had a flow cytometry DNA content slightly higher than G. hirsutum. In addition, its morphological characteristics (plant architecture, presence and size of petal spots, leaf shape) led us to conclude that this plant was AAAD thus resulting from fertilization with an unreduced AA gamete of the female G. herbaceum parent. Fluorescent In Situ Hybridization (FISH) and meiotic behavior confirmed this hypothesis. To the best of our knowledge, this is the first description of such gametes in G. herbaceum, and it opens new avenues in breeding programs. Furthermore, this plant material could provide a useful tool for studying the expression of genes duplicated in the A and D cotton genome.They acknowledge support for this project from the French Ministry for Education and Research/ ANR (Agence Nationale de la Recherche), grant MFD/AO OGM 0217. The Jean-Pierre Bourgin Institute (IJPB) benefits from the support of the LabEx Saclay Plant Sciences-SPS (ANR-10-LABX-0040-SPS).http://www.g3journal.orgam2017Plant Production and Soil Scienc