The aim of this study was to characterize phyllosphere and carposphere bacterial communities of olive trees subjected for 13 years to two different soil management systems (sustainable and conventional) in a mature olive grove located in Southern Italy. Amplified DNA fragments of the 16S ribosomal RNA eubacterial gene (16S <em>rRNA</em>) of bacteria living on leaf and fruit surface, and in fruit pulp were analyzed by denaturing gradient gel electrophoresis (DGGE). A clone library of 16S <em>rRNA</em> amplicons extracted from the bacteria living in pulp homogenates and a phylogenetic analysis were performed. Generally, the DGGE patterns of the bacteria from both the treatments clustered separately. The medium-term sustainable orchard management resulted in a higher number of bacterial species from olive fruit pulp. Phyllosphere and carposphere communities evaluated by DGGE were affected by the type of the agricultural practices adopted. A better understanding of phyllosphere and carposphere microbiota of cultivated olive plants could be useful for the promotion of plant growth, a better plant protection and a higher crop quality.
IntroductionSoil management techniques can definitely influence soil quality, acting especially on soil organic matter content, biological complexity, structure, and water holding capacity (Kladivko, 2001). In the rain-fed orchards of the semiarid Mediterranean agrosystems, where soil conservation is one of the major agronomic challenges (Ramos et al., 2011), soil management is limited by the particular climate conditions, characterized by water deficits in the springsummer period.Therefore, agricultural practices should be aimed at increasing water availability and reducing evapotranspiration losses. Tillage before the rainy period is a common practice to facilitate water supply in the soil profile, but may be more harmful for the biological component and organic matter dynamics than no-till or grass planting (Hernandez, 2005). The use of cover crops and reduced tillage may increase soil organic matter and water infiltration (Roberson et al., 1991). In particular, plant cover is a major soil quality factor not only for conservation and to increase organic matter (Vance, 2000), but also and especially as a source of microorganisms with C and energy through root exudates and plant residues (Ramos et al., 2011). On the other hand, all changes in the activity and composition of the soil microbial component, often induced by these agricultural practices, may in turn cause variations in soil fertility, thus increasing the supply of nutrients to plants (Crecchio et al., 2007).The study of single specific soil microorganisms may be useful in some cases (rhizobia, mycorrhiza), but
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.