Gene transfer from bacteria to plants was thought to be limited to the bacterial genus Agrobacterium. But other bacterial groups also contain species capable of interkingdom genetic exchange. All organisms must be able to transfer genetic informationfrom parent to progeny - without this 'vertical' gene transmission, species would simply die out. But this is not the only mechanism for transmitting genes from one organism to another. 'Horizontal' gene transfer has long been recognized as a major factor in evolution, and there are numerous likely examples of past horizontal gene transfer events. In terms of ongoing processes, bacterial conjugation (gene transmission from one bacterium to another through direct physical contact) is the most commonly cited example. The horizontal transfer of genetic material between species from different phylogenetic kingdoms - from bacteria to plants, for instance - is also possible, but had previously been documented only for members of the bacterial genus Agrobacterium. Now, on page 629 of this issue, Broothaerts et al. show that several bacterial species outside this genus are also capable of interkingdom 'sex'.
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