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Moderated conference on GMOs in the pipeline, hosted by the FAO Biotechnology Forum in 2012

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Biotech-Mod2 <[log in to unmask]>
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Biotech-Mod2 <[log in to unmask]>
Date:
Sat, 24 Nov 2012 06:39:04 +0100
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This is John Samuels joining the conference. Appologies for being a late arrival! I am a plant taxonomist, based in the United Kingdom, working independently on the Solanaceae family. I have a PhD in Plant Taxonomy (Solanaceae-brinjal wild relatives) and have worked in this field since the 1980s. I would like to contribute to the Bt brinjal discussion, focusing here on the potential for transgene transfer between Bt brinjal and other solanaceous species. 

1. Interfertility relationships between brinjal and its wild relatives in India: 

Ms. Saigal (message 44) posed the question regarding evidence of sexual incompatibility between brinjal and its wild relatives. This was based on Prof. Balasubramanian’s statement (message 33) that brinjal wild relatives are inherently sexually incompatible with cultivated brinjal. (At this point it is important to make clear the difference between cultivated brinjal (Solanum melongena L., the brinjal eggplant) and its wild relatives in India, some of which are also known as brinjals (for example, bitter brinjal, Solanum virginianum L.) and are completely different species. 

Prof. Rao’s response (message 51) refers specifically to one study of the 1980s, performed in India (Rao & Rao, 1984), which looked at the success rate of sexual crosses between brinjal and five other related species. They found, as Prof. Rao states, that certain cross-combinations were unlikely to produce fertile progeny. However, it is crucial to mention that they also found that crossing brinjal with S. violaceum Ortega (a common ruderal weed) gave a successful two-way cross, producing vigorous, highly fertile F1 hybrids! 

Many similar investigations involving brinjal and other closely-related species have been performed; useful summaries can be found in Daunay et al. (1991), Kashyap et al. (2003) and Rao (1979). More importantly, it is noteworthy that six wild relative species and four cultivated Solanum species found in India are known to be able to cross with brinjal to produce hybrids with measurable fertility Samuels (2012a). Message 51 also suggests that the chances of natural hybridization taking place are very low. In contrast to this, there is a considerable body of opinion that adheres to the idea that brinjal and its closest wild relatives can freely interchange genes by natural hybridization (e.g. Karihaloo & Rai, 1995; Meyer et al., 2012; Weese & Bohs, 2010). There is also a comparably large body of opinion which supports the idea that brinjal exists in feral form (see Karihaloo & Rai, 1995) and, like most solanums, will readily adapt to a ruderal or adventive mode of survival.         

2. The brinjal centre of origin of controversy: 

Dr. Kumar (message 46) and Prof. Rao (message 45) referred to the centre of origin of brinjal-this is a relevant consideration in relation to the possibility of transgene transfer. The exact whereabouts of the centre of origin of brinjal is still open to discussion. Recent reference has been made to the African “origins” of S. melongena (e.g. Weese & Bohs, 2010). However, this relates to S. incanum L., the putative progenitor of brinjal. This species had its origins in East Africa and, as it evolved, migrated across north-east Africa, the Middle East and into northern India (Samuels, 2012b). It therefore seems likely that brinjal domestication took place in India, and one of the most recent genomic analyses supports this (Meyer et al., 2012). But, in the context of Bt brinjal, the crucial relevance of the centre of origin is not so much its precise location, as the fact that brinjal wild relatives will be found there (Samuels, 2011). Indeed, in India, of approximately 50 Solanum species (wild and cultivated) found there, 23 species belong to the three sections with the potential to form fertile hybrids with brinjal (Samuels, 2012a). Added to this, India is certainly one of several centres of diversity of brinjal, comprising many ancient, traditional and modern landraces and varieties of the crop.  

I hope that this helps to put into context the relevance and importance of the two main points above.    

Dr John Samuels
Novel Solanaceae Crops Research Project
Penzance 
Cornwall
TR20 8XD
United Kingdom
Tel: 0044 (0)1736 333773
E-mail: john.samuels (at) virgin.net 

References:
Daunay, M-C., Lester, R.N. & Laterrot, H. 1991. The use of wild species for the genetic improvement of brinjal egg-plant (Solanum melongena) and tomato (Lycopersicon esculentum). In: Hawkes, J.G., Lester, R.N., Nee, M. & Estrada, N. (eds.), Solanaceae III: Taxonomy, Chemistry, Evolution. Kew: Royal Botanic Gardens, 389-412. 
Karihaloo, J.L. & Rai, M. 1995. Significance of morphological variability in Solanum insanum L. (sensu lato). Plant Genetic Resources Newsletter 103: 24-26.
Kashyap, V., Vinod Kumar, S., Collonier, C., Fusari, F., Haicour, R., Rotino, G.L., Sihachakr, D. & Rajam, M.V. 2003. Biotechnology of eggplant. Scientia Horticulturae 97 (1): 1-25.
Meyer, R.S., Karol, K.G., Little, D.P., Nee, M.H. & Litt, A. 2012. Phylogeographic relationships among Asian eggplants and new perspectives on eggplant domestication. Molecular Phylogenetics and Evolution 63, 685-701.
Rao, N.N. 1979. The barriers to hybridization between Solanum melongena and some other species of Solanum. In: Hawkes, J.G., Lester, R.N. & Skelding, A.D. (eds.), The Biology and Taxonomy of the Solanaceae. London: Academic Press, 605-614. 
Rao, S.V. & Rao, B.G.S. 1984. Studies on the crossability relationships of some spinous solanums. Theoretical and Applied Genetics 67: 419-426.
Samuels, J. 2011. Centre of origin and the Bt brinjal controversy. Current Science 101 (4): 469. 
Samuels, J. 2012a. Genetically Engineered Bt brinjal and the Implications for Plant Diversity-Revisited. Novel Solanaceae Crops Project, UK. http://www.greenpeace.org/seasia/ph/PageFiles/415937/GE-Bt-brinjal-revisited.pdf accessed 22 November 2012. 
Samuels, J. 2012b. Solanum incanum s.l. (Solanaceae): taxonomic relationships between S. incanum, S. campylacanthum, S. panduriforme, and S. lichtensteinii. Kew Bulletin 67, 401-411.  
Weese, T., Bohs, L. 2010. Eggplant origins: out of Africa into the Orient. Taxon 59 (1), 49-56.

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