THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE

31 July 2003

Dear friends and colleagues,

RE: STUDY ON GENE FLOW AND EFFECTS ON GENETIC DIVERSITY

We wish to bring to your attention a study on gene flow associated with genetic engineering and its effects on the genetic diversity of landraces and wild relatives. 

Contamination of traditional crops by genes from GM crops has been documented in many parts of the world and is becoming common wherever GM crops are planted, and increasingly acknowledged as inevitable. The situation becomes more critical if such gene flow occurs in centers of diversity.

The study entitled “Possible effects of (trans)gene flow from crops on the genetic diversity from landraces and wild relatives” by Paul Gepts and Roberto Papa and published in the journal Environ. Biosafety Res. 2 (2003) 89-103 is available online at: www.edpsciences.org.

We reproduce below a short review from the study:

“Gene flow is a potential concern associated with the use of transgenic crops because it could affect genetic diversity of related landraces and wild relatives. This concern has taken on added importance with the looming introduction of transgenic crops in centers of crop domestication (Mexico, China) and those producing pharmaceutical compounds. For gene flow to take place among cultivars and their wild relatives, several steps have to be fulfilled, including the presence of cultivars or wild relatives within pollen or seed dispersal range, the ability to produce viable and fertile hybrids, at least partial overlap in flowering time, actual gene flow by pollen or seed, and the establishment of crop genes in the domesticated or wild recipient populations. In contrast with domestication genes, which often make crops less adapted to natural ecosystems, transgenes frequently represent gains of function, which might release wild relatives from constraints that limit their fitness.

In most sexually reproducing organisms, the chromosomal region affected by selection of a single gene amounts to a small percentage of the total genome size. Because of gene flow, the level of genetic diversity present in the domesticated gene pool becomes a crucial factor affecting the genetic diversity of the wild gene pool. For some crops, such as cotton and maize, the introduction of transgenic technologies has led to a consolidation of the seed industry and a reduction in the diversity of the elite crop gene pool. Thus, diversity in improved varieties grown by farmers needs to be monitored. Several areas deserve further study, such as the actual magnitude of gene flow and its determinants in different agroecosystems, the long-term effects of gene flow on genetic diversity both across gene pools and within genomes, the expression of transgenes in new genetic backgrounds, and the effects of socio-economic factors on genetic diversity.”

With best wishes,

Lim Li Lin and Chee Yoke Heong

Third World Network

121-S Jalan Utama

10450 Penang

Malaysia

Email: twnet@po.jaring.my