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Climate change is shifting the distribution of species, and may have a profound impact on the ecology and evolution of species interactions. However, we know little about the impact of increasing temperature and changing rainfall patterns on the interactions between plants and their beneficial and antagonistic root symbionts. Here, we used a reciprocal multifactorial growth chamber experiment with seeds and soil microbial communities from three origins to investigate the impact of temperature and soil moisture on the growth, arbuscular mycorrhizal (AM) fungal colonization and root‐associated fungal community of a perennial herb. Moreover, we tested whether plants and AM fungi performed better or worse when plants were grown with their local soil biota, for example, due to plant adaptation or changes in the genetic or species composition of the soil microbial community. Temperature and soil moisture generally increased plant growth, whereas temperature but not soil moisture increased AM fungal colonization. The strength and direction of the plants' response to temperature were dependent on soil moisture and differed among plant populations, and AM fungal colonization was further affected by the origin of the soil microbial community. The root‐associated fungal community structure was impacted by temperature, soil moisture and the soil microbial origin, with interactive effects between the microbial origin and the abiotic environment. Plant biomass was lower when plants were grown with their local soil microbes, potentially due to intraspecific negative plant–soil feedbacks. Synthesis. Our findings indicate that, beyond a relatively uniform increase of plant growth and arbuscular mycorrhizal (AM) fungal colonization with increasing temperature, plants and root‐associated fungi of different origins will vary in their response to climate change (i.e. elevated temperature and shifts in rainfall). This may create pronounced, but difficult to predict, spatial and temporal variation in the ecology and evolution of plant–microbe interactions with a changing climate.

Microbial interactions in the phyllosphere have been shown to fulfil important functions for plant health. Yet, little is known about such types of microbial interactions in crop pathosystems and if they are influence by host plant genotype. In this work the endophytic and epiphytic fungal community in olive tree leaves with and without symptoms of olive leaf spot (OLS) disease, from three cultivars with different susceptibilities to OLS was compared. Fungal community was analysed by culture-dependent methods. Results indicate that fungal community differs in size and composition between asymptomatic and symptomatic leaf, especially within epiphytic community. Endophytes varied less probably due to complexity enhancement of interactions, since living host tissues are involved. Host genotype had a structuring effect on the composition of fungal communities only in asymptomatic leaves. Symptomatic leaves displayed a similar fungal community among cultivars, which composition appears to be disease-specific. OLS disease also differentially influenced fungal flora of the three cultivars, and the greatest differences between asymptomatic and symptomatic leaves were observed in the tolerant cultivar. Some fungal taxa were found to be specific to either asymptomatic or symptomatic leaves, which suggest that they might have competitive or cooperative activity with the pathogen, within and outside leaf tissues. The role of these fungi as “pathogen antagonist” or “pathogen facilitator” must be investigated in the future. info:eu-repo/semantics/publishedVersion

Olive tree phyllosphere is colonized by a diverse microbial assemblage that may interact with pathogenic fungi, making them potential candidates for disease supression. Olive knot (OK) is a disease caused by the bacterium Pseudomonas savastanoi pv. savastanoi (Psv.) with significant economic losses in olive tree (Olea europaea L.). With this work we want to evaluate the effect of cultivar and OK infection on both endo- and epiphytic fungal community inhabiting olive twig tissues. For this, fungal composition and diversity was assessed in both asymptomatic and OK-symptomatic twigs of tree co-occurring olive cultivars with different susceptibilities to OK disease. The identification of isolated species was performed by ITS rDNA sequencing. The cultivar and OK infection were important in shaping both endophytic and epiphytic fungal communities. Fungal community composition was found to differ significantly (p=0.005) between olive tree cultivars, being Nectriaceae the dominant family in cvs. Cobrançosa and Verdeal Transmontana, whereas Pleosporaceae was dominant in the cv. Madural. Epiphytic and endophytic fungal communities also differed in size and in composition in asymptomatic and OK-symptomatic twigs, for the three cultivars. In general, asymptomatic twigs were more diverse and rich (up to 1.4-fold) when compared to OK-symptomatic twigs. Among the species identified in the asymptomatic tissues, Cladosporium cladosporioides and Chromelosporium carneum were the most frequently isolated within epiphytic and endophytic community, respectively; whereas in the OK-symptomatic tissues Cladosporium sp. and Fusarium lateritium were the most frequently isolated within epiphytic and endophytic community, respectively. According to indicator species analysis C. carneum, Pyronema dosmesticum and Phoma aloes (IndVal up to 0.56) may be promising species in the OK suppression. Better acknowledgement should be developed in order to uncover their role on plant health., FEDER funds through COMPETE (Programa Operacional Factores de Competitividade} and by national funds by FCT [Fundação para a Ciência e a Tecnologia) in the framework of the project EXCL/AGR-PRO/0591/2012. T. Gomes thanks FCT, POPH-QREN and FSE for PhD SFRH/BD/98127/2013 Grant, info:eu-repo/semantics/publishedVersion

Olive leaf spot (OLS), a disease that usually occurs on the upper surface of the olive leaf, is caused by the fungus Fusicladium oleagineum with an ability to grow epiphytically and to enter inner leaf tissues. ln this work was studied the effect that host plant, at different levels (i.e. at cultivar level, in resistance to the fungal pathogen, and F. oleogineum infection), have on the phyllosphere fungal community composition of olive tree. For this, both epiphytic and endophytic fungal community inhabiting OLS-symptomatic and asymptomatic leaves of three co-occurring cultivars with different susceptibilities to OLS were compared, after isolation and identification of species by ITS rDNA sequencing. The results indicate that the presence of OLS on leaves had a major effect on the fungal community composition than the host plant, either at cultivar level or of their resistance to the fungal pathogen. Both diversity and abundance of epiphytes in asymptomatic leaves were significantly higher (up to 2.O-fold) than in symptomatic leaves, Although less pronounced, this trend was also evident in endophytes of two of the cultivars surveyed. Among the species identified in asymptomatic leaf, Cladosporium clodosporÍoides and Chromelosporium carneum were the most frequently isolated within epiphytic and endophytic fungal communities, respectively; whereas in symptomatic leaf, Cladosporium sp, and Pseudocercosporo cladosporioides, were the most frequently isolated within epiphytic and endophytic fungal communities, respectively. Determination of indicator value indices has shown significant preference/specificity of four species with asymptomatic leaves, and of two species with symptomatic leaves. Based on this analysis both Atternorio sp. and Tricharina striisporo seems to be the species with the most potential for OLS disease suppression. Future research needs to decipher these complex and dynamic interaction networks and assess their role in plant health., info:eu-repo/semantics/publishedVersion

Soil microbial mutualists of plants, including mycorrhizal fungi, non-mycorrhizal fungi and plant growth promoting rhizobacteria, have been typically characterized for increasing nutrient acquisition and plant growth. More recently, soil microbes have also been shown to increase direct plant defense against above- and belowground herbivores. Plants, however, do not only rely on direct defenses when attacked, but they can also recruit pest antagonists such as predators and parasitoids, both above and belowground, mainly via the release of volatile organic compounds (i.e., indirect defenses). In this review, we illustrate the main features and effects of soil microbial mutualists of plants on plant indirect defenses and discuss possible applications within the framework of sustainable crop protection against root- and shoot-feeding arthropod pests. We indicate the main knowledge gaps and the future challenges to be addressed in the study and application of these multifaceted interactions.