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

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Date: Fri, 30 Nov 2012 16:18:40 +0100
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This is John Samuels (Message 60) again. The first part below relates to Messages 67 and 78 from  A. Kumar and Aruna Rodrigues, respectively. The second section expands further upon A. Kumar's comments.

1. Cross-fertilisation between brinjal and its wild relatives cannot be ruled out.

I would like to strongly agree with the first part of Message 67 which says that: "...cross-fertilization between cultivated brinjal and its wild relatives cannot be ruled out." In fact, this phenomenon was proven to be a reality by some of the biosafety risk assessments performed on Bt brinjal in India. Of these, the following two crossability studies performed by the Indian Institute of Vegetable Research (IIVR, 2008, 2009) at Varanasi, Uttar Pradesh are of note. In the first study, cross-pollinations were artificially performed, using nine cultivated lines of brinjal (Solanum melongena) and five species of wild relatives. It was found that the nearest wild relative, S. incanum, was a successful staminate parent, insofaras the setting of fruit with viable seeds by the S. melongena pistillate parents. (This was expected as, sixteen years earlier, the same interspecific cross-combination was shown to produce fruits containing viable seed from which a fertile F1 generation was grown [Lester & Hasan, 1991]). In the second study, the same methodology was used, attempting cross-pollinations between four Bt brinjal hybrid lines carrying the Cry 1Ac transgene, and plants from a single S. incanum accession. In this study, all cross-combinations were successful in both directions. These results were of additional interest because, ten years previously, a one-way fertility barrier (whereby cross-pollinations are unsuccessful when S. incanum is the pollen acceptor) had been demonstrated between S. incanum and S. melongena (Lester & Kang, 1998). There is a strong indication that this barrier was somehow alleviated in the IIVR crosses involving Bt-S. melongena. The implications for transgene transfer to S. incanum are thus considerable, as outcrossing to S. incanum would necessitate S. incanum being the female parent.

In their consideration of Bt brinjal biosafety data, the Expert Committee (EC-II) on Bt brinjal (GEAC, 2009) alluded to the fertility barrier in the first study, but no comment was made regarding the more significant findings of the second study. This may have been because the crucial data from the second study was not available at the time of the EC-II meeting, in January 2009. Furthermore, both studies were limited by the extent to which they examined crossability. To be able to study the true potential for outcrossing (and thus potential introgression of transgenes into the untransformed genomes of wild relatives) it is necessary to take this kind of study further. E.g. similar investigations at Birmingham University, UK (see Lester et al., 2001), during the 1970s-1990s (and elsewhere) took fruit set to be only a preliminary indicator of interfertility. Based on this work, the production of viable, germinable seeds, producing a vigorous, fertile F1 (or subsequent) generation is taken to be a reliable indicator of sexual compatibility. In this light, the two investigations of crossability discussed above can be taken as useful starting points, prior to more detailed and extensive investigations which should follow. To the best of my knowledge, these have yet to be undertaken.

2. Efforts to transfer BFSB resistance to brinjal/other alternatives to Bt brinjal?

Relatively recent efforts to transfer brinjal fruit and shoot borer (BFSB) resistance from wild relatives to brinjal (e.g. Baksh, 1979; Behera & Singh, 2002; etc.) have shown that a good rate of success is achievable. Resistance was reported in the interspecific hybrids formed from crosses between brinjal and both S. incanum and S. violaceum (= S. indicum). Additionally, the biological control option is another avenue that merits more scrutiny. Srinavasan (2008) showed that there are several known natural predators and parasites, such as the Ichneumonid Trathala flavo-orbitalis Cameron, which attack BFSB. Nagalingam et al. (2006) observed its ability to synchronise with BFSB, recognising it as a potential bio-control candidate. For small-scale farmers and producers the logical step of merely isolating the crop from the predator seems yet another option! A recent study by Krishna Kumar et al. (2010) showed that simple physical barriers such as the use of insect-proof netting are very effective in reducing BFSB damage to brinjal crops. They add that this technique remains a clear alternative to GM brinjal. Thus, development of untransformed brinjal with genetic resistance to BFSB, perhaps cultivated with the aid of biological and physical control measures, may provide equally effective means of combatting crop damage.

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

Baksh, S. 1979. Cytogenetic studies on the F1 hybrid Solanum incanum L. x Solanum melongena L. variety "Giant of Banaras." Euphytica 28: 793-800.

Behera, T.K. & Singh, G. 2002. Studies on resistance to shoot and fruit borer (Leucinodes orbonalis) and interspecific hybridization in eggplant. Indian Journal of Horticulture 59 (1): 62-66.

GEAC. 2009. Report of the Expert Committee (EC-II) on Bt Brinjal Event EE-1. Genetic Engineering Approval Committee (GEAC), Ministry of Environment and Forests, Government of India.

IIVR. 2008. Assessment of crossability of Solanum melongena with other Solanum species. http://moef.gov.in/divisions/csurv/geac/Bt_Brinjal/Assessment%20of%20crossability.pdf (27 KB)

IIVR. 2009. Assessment of crossability of Bt brinjal (Solanum melongena) with Solanum incanum. http://moef.gov.in/divisions/csurv/geac/Bt_Brinjal/Assessment%20of%20crossability%20of%20Bt%20Brinjal.pdf (2 MB).

Krishna Kumar, N.K., Sreenivasa Murthy, D., Ranganath, H.R., Krishnamoorthy, P.N., Saroja, S. 2010. Economics of management of eggplant shoot and fruit borer (ESFB), Leucinodes orbonalis Guenee raised under low cost net house. In: Prohens J. & Rodriguez-Burruezo A. (eds.), Advances in Genetics and Breeding of Capsicum and Eggplant. Editorial de la Universitat Politecnica de Valencia, Spain, 171-177.

Lester, R.N. & Hasan, S.M.Z. 1991. Origin and domestication of the brinjal eggplant, Solanum melongena, from S. incanum  in Africa and Asia. In: Hawkes JG, Lester RN, Nee M, Estrada N, (eds.), Solanaceae III: Taxonomy, Chemistry, Evolution. Kew, Royal Botanic Gardens, Kew, 369-387.

Lester, R.N., Hawkes, J.G., Daunay, M-C., van der Weerden, G.M., Barendse, G.W.M. 2001. The sources, successes and successors of the Birmingham University Solanaceae collection (1964-2000). In: Solanaceae V: advances in Taxonomy and Utilization (eds. R.G. van den Berg, G.W.M. Barendse, G.M. van der Weerden & C. Mariani), 251-274. Nijmegen University Press, Netherlands.

Lester, R.N. & Kang, J.H. 1998. Embryo and endosperm function and failure in Solanum species and hybrids. Annals of Botany 82: 445-453.

Nagalingam, T., Wiyayagunasekara, H.N.P., Hemachandra, K.S., Nugaliyadde, L. 2006. Association of parasitoid Trathala flavo-orbitalis with brinjal shoot and pod borer Leucinodes orbonalis in the mid-country region of Sri Lanka. Sri Lankan Journal of Agricultural Science 43: 124-132.

Srinivasan, R. 2008. Integrated pest management for eggplant fruit and shoot borer (Leucinodes orbonalis) in South and Southeast Asia: past, present and future. Journal of Biopesticides 1: 105-112.

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