“…Therefore, an alternative approach to identify bacterial factors involved in infection processes could be based on the search for bacterial genes specifically up‐regulated in planta . Recently, a large number of bacterial genetic techniques have been developed leading to the identification and further analysis of factors essential for in vivo growth, such as IVET ( In Vivo Expression Technology) and RIVET (Reverse IVET) techniques (Slauch and Camilli, 2000), signature tagged mutagenesis (STM), and difference fluorescent induction (DFI), amongst others (Handfield and Levesque, 1999). Moreover, classical in vitro systems do not always represent an exact picture of what is happening in plant–bacteria interactions, because, in many cases, the infection processes are regulated and stimulated by host factors (Finlay and Falkow, 1997).…”