From Mark Tester and Peter Langridge, Australian Centre for Plant Functional Genomics
It was good to see your comment that we need to consider the genes that are being deployed rather than the technique used to introduce them into crops (5 January, p 3 and p 28). However, we were puzzled by the claims that crops with increased drought or salt tolerance “might create highly invasive plants”.
Crops are highly dependent on humans for their survival, so it is very unlikely they will become invasive because of the introduction of just one tolerance trait. Modern cereals, the main crops that feed the world, have at least two traits that reduce their ability to be ecologically competitive: they do not shed their seeds upon maturity, which makes crops easier to harvest but reduces their ability to disperse; and the seeds have lost most dormancy traits, which makes them easier to grow but reduces their ability to survive for long periods in soil.
This means that crops are unlikely to become weeds just by increasing their drought and salt tolerance, whether this is done by genetic modification or by conventional means. Increasing drought and salt tolerance has the potential to increase yields enormously, with minimal risk to the environment.
Adelaide, South Australia
