BT gene in GM crops harmful for growth

Date:06-07-2011

A team of Indian scientists has found that genetic modification (GM) will have a detrimental effect on the growth and development of plants.

This is the first time that scientists have found that the Bt gene will trigger major problems in plants like stunted growth and sterility. Thus far, studies have centred on the toxicity of the Bt gene to animals and human beings.

There has been considerable interest and activity in genetically engineering insect-resistant crop plants using ‘Cry genes’ encoding insect toxins from the soil bacterium Bacillus thuringiensis (Bt). The proteins encoded by these genes are called Bt-toxins and are thought to specifically affect only certain insects and not other organisms or the plants themselves.

However, the team from the laboratory of Dr Pradeep Burma in the Department of Genetics at the University of Delhi, South Campus, has found that expression of the Bt-toxin ‘Cry1Ac’ in cotton and tobacco is detrimental to the growth and development of those plants. The study was published in the June issue of Journal of Biosciences.

"Many of the transgenic plants obtained showed developmental defects comprising abnormal growth (stunting) and/or sterility. These symptoms suggest that expression of Cry1Ac could be causing growth defects in plants,” the team observed.

Consistent with this explanation, the researchers found that a majority of transgenic plants had very low or undetectable levels of Cry1Ac, and that all plants having appreciable levels of Cry1Ac showed developmental abnormalities. This indicates a correlation between the levels of Cry1Ac expression and the developmental defects in the plants. Plants release defence-related molecules to fight the toxicity induced in them through Bt technology.

Though studies have not been conducted to establish whether these defence-related molecules will cause harm to human beings when they are consumed, scientists here feel that the toxins released may also be detrimental to human and animal health.

Source: Deccan Chronicle