Abstract
Cotton is the second most important cash crop contributing about 15% to the annual foreign earning in Tanzania and is purely from Gossypium hirsutum L. cultivars. Gossypium barbadense L., a textile source in other parts of the world occurs as a feral perennial of ornamental and medicinal value in home gardens. G. barbadense L. is a natural host of the red bollworm, a destructive pest to cotton. The Southern Highlands (SH) of Tanzania have been quarantined from cotton production to control spread of the red bollworm to other growing areas. Transgenic cotton expressing the delta-endotoxin genes from Bacillus thuringiensis(Bt) offers an alternative control to the pest and reduced dependence on insecticide. Gene flow between wild or valued feral relatives and transgenic crops is a biosafety concern should transgene escape result in resistance development and contamination of germplasm. Potential gene flow between feral G. barbadense(including accessions Gb1 and Gb2) from the SH and G. hirsutum cultivars was assessed using controlled hybridization. The crosses produced fertile F1 but intraspecific seeds from G. barbadense did not germinate.G. barbadense is more likely to receive than donate genes implying development of pest resistance if introgressed filial generations express the Bt product. Key words: Hybridization, gene flow, morphological markers, feral cotton, bollworm, Bacillus thuringiensis(Bt) cotton.
Highlights
Cotton is the world’s most important natural textile fibre and a significant oilseed crop that provides income to approximately 100 million families whereas 150 countries are involved in cotton import and export
In Tanzania, cotton is grown by small holder farmers on less than 2 ha with different cultivars on the same plot
A study by Shilla et al (2007) to assess distribution and diversity of feral G. barbadense in the Southern Highlands showed that there was a clear variation within feral accessions based on morphology characters suggesting in vivo interspecific crossing and/ or environmental adaptation
Summary
Cotton is the world’s most important natural textile fibre and a significant oilseed crop that provides income to approximately 100 million families whereas 150 countries are involved in cotton import and export. Production of Bt cotton poses biosafety concerns including potential impacts on non-target species and resistance evolution and gene flow (Andow and Zwahlen, 2006). These concerns vary with ecogeographic conditions and cannot be extrapolated to other areas it is generally recommended that site specific assessments are conducted prior to introduction of a genetically modified crop. Likewise in Australia, commercial production of Bollgard II cotton (containing 2 Bt genes) and Bollgard II/Roundup Ready cotton has been restricted to south of latitude 22° to prevent gene flow to native cotton in northern Australia (Mayer and Stirling, 2004) These restrictions set precedence on the need for gene flow studies to assess not just the potential for transgene escape in a specified eco-geographic area but to establish the consequences of the escape. The data derived intends to postulate potential for bollworm resistance build up against the Bt toxin, should Bt cotton be deployed as a means of bollworm control in Tanzania
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
