Ana M. Romero

Tomato genotype and Azospirillum inoculation modulate the changes in bacterial communities associated with roots and leaves

Aims:  To evaluate the effect of plant variety and Azospirillum brasilense inoculation on the microbial communities colonizing roots and leaves of tomato (Lycopersicon esculentum Mill.) plants.

Functional groups of plant pathogens in agroecosystems: a review

The concept of functional groups (set of species having similar physiological, ecological or life-history traits) has been largely used for plants, microorganisms, nematodes or insects in agroecosystems. However, this concept has been rarely applied to describe assemblages of plant pathogens. Yet, classification systems in plant pathology resemble this functional approach, as they address different disease processes or life history traits. In this review, we discuss advantages and drawbacks of current classification systems in relation to their application to the ecological management of crop diseases. Then, we propose to reorganize one of the classical plant-pathogen systems in a dichotomous key of functional groups obtained by combining two life-history traits: dispersal and survival strategies. The six functional groups proposed here are soil inhabitants; soil survivors; debris-seed-borne; air-borne; seed-borne, and vector-borne pathogens. We applied these groups to characterize pathogens of two major crops, wheat and tomato, grown in temperate climate regions. Our contribution intends to provide a comprehensive conceptual framework for the design of crop disease management strategies based on ecological principles, as well as to facilitate the interpretation of the occurrence of epidemics in response to the agricultural practices applied in real-world agroecosystems.

Legacy of historic ozone exposure on plant community and food web structure

Information on whole community responses is needed to predict direction and magnitude of changes in plant and animal abundance under global changes. This study quantifies the effect of past ozone exposure on a weed community structure and arthropod colonization. We used the soil seed bank resulting from a long-term ozone exposure to reestablish the plant community under a new low-pollution environment. Two separate experiments using the same original soil seed bank were conducted. Plant and arthropod richness and species abundance was assessed during two years. We predicted that exposure to episodic high concentrations of ozone during a series of growing cycles would result in plant assemblies with lower diversity (lower species richness and higher dominance), due to an increase in dominance of the stress tolerant species and the elimination of the ozone-sensitive species. As a consequence, arthropod-plant interactions would also be changed. Species richness of the recruited plant communities from different exposure histories was similar (≈ 15). However, the relative abundance of the dominant species varied according to history of exposure, with two annual species dominating ozone enriched plots (90 ppb: Spergula arvensis, and 120 ppb: Calandrinia ciliata). Being consistent both years, the proportion of carnivore species was significantly higher in plots with history of higher ozone concentration (≈3.4 and ≈7.7 fold higher in 90 ppb and 120 ppb plots, respectively). Our study provides evidence that, past history of pollution might be as relevant as management practices in structuring agroecosystems, since we show that an increase in tropospheric ozone may influence biotic communities even years after the exposure.