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Bt brinjal, wild relatives and biodiversity
In the commentary on Bt brinjal and GM This general concern was highlighted additional pest resistance upon wild crops, Banerji has put forward valid by the Cartagena Protocol on Bio-relatives, these genes might also induce recommendations, some of which relate safety to the Convention on Biological a selective advantage, encouraging to pressures on the physical environment. Diversity, to which India is a signatory. such plants to become overbearing weeds There is another issue that has potentially In 2006, the Independent Expert Com-with negative effects on ecological far-reaching consequences on the living mittee on Bt Brinjal expressed concerns balance and biodiversity. A ‘precautioenvironment. This relates to the release over the possibility of cross-transfer of nary approach’ towards developing of transgenic crops such as Bt brinjal into genes from the GM crop to its wild rela-this crop variant was therefore recomtheir centre of origin. tives via hybridization. While conferring mended.
Several studies on the interfertility of brinjal with some of its wild relatives have been carried out. However, these have been rather limited in number. Solanum incanum L., one of the bitter tomatoes, is the purported wild ancestor of the brinjal eggplant and occurs naturally in some parts of India. S. incanum is partially interfertile with cultivated S. melongena and is also ‘easily crossable’ with Bt brinjal hybrids carrying the Cry1Ac gene. Furthermore, in parts of India there are other wild, as well as semi-wild and weedy solanums, which are close relatives of S. incanum and brinjal, and tentatively names ‘S. insanum L.’, ‘S. cumingii Dunal’, etc. However, their precise taxonomic identities are, as yet, unclear and they are notoriously difficult to distinguish, both from each other and from S. melongena and S. incanum. Interfertility amongst S. insanum, S. cumingii and S. melongena has been demonstrated experimentally and, along with S. incanum, these three taxa are therefore potentially successful acceptors of Bt brinjal pollen. Although the foregoing crosses were produced as a consequence of artificial cross-pollinations they are an indication of what may be possible in nature, where the naturally occurring relatives of brinjal often occur as adventives amongst or near cultivations. Although no instances of natural inter-specific hybridization with wild species have been reported for cultivated brinjal this does not preclude the possibility of this phenomenon.
Wild relatives vary in their ability to form successful crosses with brinjal. For example, S. kurzii Brace ex Prain (= S. sanitwongsei Craib), a species of north eastern India, known as ‘tita baigan’, shows high crossing success with S. melongena. S. violaceum Ortega (= S. indicum L.), found across much of India, shows some interfertility with brinjal according to Behera and Singh, but is also described elsewhere as being non-compatible with it. There are still other wild species such as S. barbisetum Nees in need of study, which may show crossability with S. melongena.
On 9 February 2010, a moratorium on the commercialization of Bt brinjal was imposed in India. Scientists thus have a chance to develop a better understanding of the taxonomic inter-relationships of brinjal and its relatives, as well as furthering their knowledge of breeding behaviour. This would allow more accurate prediction of the likelihood of cross-transfer of genes, and may encourage the re-consideration of breeding strategies for untransformed brinjal involving wild relatives already possessing relevant pest and disease resistance.
A new ten-year strategic plan devised by the Parties to the Convention on Biological Diversity (COP10) will soon be put into action. It is comprised of 20 targets aimed at reducing pressures on biodiversity and taking urgent action to save and restore nature. A certain number of these relate to the genetic diversity of crops and their wild relatives, and also to the management of biological invasions. In this light, continued, careful consideration should be given to the study of the potential for cross-transference of genes between Bt brinjal and its wild and weedy relatives, and the possible implications.
Source : Current Science |
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