Beschreibung:
<jats:p>In order to acquire a better understanding of the spatial and temporal variations of genetic diversity of <jats:italic>Burkholderia cepacia</jats:italic> populations in the rhizosphere of <jats:italic>Zea mays</jats:italic>, 161 strains were isolated from three portions of the maize root system at different soil depths and at three distinct plant growth stages. The genetic diversity among <jats:italic>B. cepacia</jats:italic> isolates was analysed by means of the random amplified polymorphic DNA (RAPD) technique. A number of diversity indices (richness, Shannon diversity, evenness and mean genetic distance) were calculated for each bacterial population isolated from the different root system portions. Moreover, the analysis of molecular variance (
<jats:sc>amova</jats:sc>) method was applied to estimate the genetic differences among the various bacterial populations. Our results showed that, in young plants, <jats:italic>B. cepacia</jats:italic> colonized preferentially the upper part of the root system, whereas in mature plants, <jats:italic>B. cepacia</jats:italic> was mostly recovered from the terminal part of the root system. This uneven distribution of <jats:italic>B. cepacia</jats:italic> cells among different root system portions partially reflected marked genetic differences among the <jats:italic>B. cepacia</jats:italic> populations isolated along maize roots on three distinct sampling occasions. In fact, all the diversity indices calculated indicated that genetic diversity increased during plant development and that the highest diversity values were found in mature maize plants, in particular in the middle and terminal portions of the root system. Moreover, the analysis of RAPD patterns by means of the
<jats:sc>amova</jats:sc> method revealed highly significant divergences in the degree of genetic polymorphism among the various <jats:italic>B. cepacia</jats:italic> populations.</jats:p>