A gene from an Indian wild relative was used to confer resistance to varieties that are now grown across 11 million ha of Asian rice fields. Genetic diversity helps crops to withstand changes in environment, climate and agricultural methods as well as threats from pests and diseases. In each of the planet's diverse ecosystems, biological diversity is at the root of a complex ecological balance. The introduction of new, highly uniform varieties has resulted in the loss of traditional farmers' varieties. Unfortunately, genetic erosion is almost always associated with - or even preceded by loss of the knowledge regarding varieties and their uses.
Genetic erosion reduces the material available for use in plant improvement.
At the same time, uniformity makes crops much more vulnerable to changes in the presence of pests and diseases by narrowing their genetic base - the stockpile of characteristics that can provide crucial resistance or immunity. Deforestation is a major cause of loss of species, be they plant or animal. It has been estimated that the clearing of closed tropical rainforests could account for the loss of as many as 100 species each day. Deforestation will be the single greatest cause of species loss in the next 50 years. Today, about 6 million accessions are stored worldwide in more than l 000 genebanks.