Host affinity of endophytic fungi and the potential for reciprocal interactions involving host secondary chemistry

Abstract

Premise Interactions between fungal endophytes and their host plants present useful systems for identifying important factors affecting assembly of host‐associated microbiomes. Here we investigated the role of secondary chemistry in mediating host affinity of asymptomatic foliar endophytic fungi using Psychotria spp. and Theobroma cacao (cacao) as hosts. Methods First, we surveyed endophytic communities in Psychotria species in a natural common garden using culture‐based methods. Then we compared differences in endophytic community composition with differences in foliar secondary chemistry in the same host species, determined by liquid chromatography–tandem mass spectrometry. Finally, we tested how inoculation with live and heat‐killed endophytes affected the cacao chemical profile. Results Despite sharing a common environment and source pool for endophyte spores, different Psychotria host species harbored strikingly different endophytic communities that reflected intrinsic differences in their leaf chemical profiles. In T. cacao, inoculation with live and heat‐killed endophytes produced distinct cacao chemical profiles not found in uninoculated plants or pure fungal cultures, suggesting that endophytes, like pathogens, induce changes in secondary chemical profiles of their host plant. Conclusions Collectively our results suggest at least two potential processes: (1) Plant secondary chemistry influences assembly and composition of fungal endophytic communities, and (2) host colonization by endophytes subsequently induces changes in the host chemical landscape. We propose a series of testable predictions based on the possibility that reciprocal chemical interactions are a general property of plant–endophyte interactions.

Endophytic colonization of tomato plants by the entomopathogenic fungus Beauveria bassiana for controlling the South American tomato pinworm, Tuta absoluta

“…Beauveria and Metarhizium produce a range of toxic compounds, including the cyclic peptides beauvericin, bassianolide and destruxin (Strasser et al 2000;Wang and Xu 2012;Golo et al 2014). It is believed that fungal toxins play an important role in the pathogenicity process during infection of the host insect (Samuels et al 1988), however they could also be expressed during endophytic colonization, protecting the plants from herbivores (Tan and Zou 2001;Christian et al 2020). Destruxin A was detected in Spodoptera littoralis larvae (Lepidoptera: Noctuidae) and B. tabaci nymphs fed on tomato and melon leaves endophytically colonized by M. brunneum (Resquín-Romero et al 2016;Garrido-Jurado et al 2017).…”

“…Reduced insect performance on plants containing EPF as endophytes can result from feeding inhibition (Vega et al 2008;Christian et al 2020). Experiments have shown reduced feeding of Ostrinia nubilalis (Lepidoptera; Crambidae) on corn plants with endophytic B. bassiana (Bing and Lewis, 1991;Vega et al 2008).…”

Foliar fungal endophyte community structure is independent of phylogenetic relatedness in an Asteraceae common garden

“…Moreover, relatively little of the observed variation in FFE community structure was explained by any of the factors tested here. Host phylogenetic relatedness has often been used as a proxy for understanding complex ecological and evolutionary processes because it is simpler to measure than an array of functional traits and relatively inexpensive with the increasing availability of genetic sequence data (Cavender-Bares et al, 2009).…”

Host Specificity of Endophytic Fungi from Stem Tissue of Nature Farming Tomato (Solanum lycopersicum Mill.) in Japan

“…Endophytic composition and diversity can be shaped by several factors, such as host genotypes, tissue origin, local environmental conditions, nutrient availability and interactions with soil fungi and bacteria [5,[76][77][78][79][80][81]. Therefore, we predicted that endophytic composition and diversity would exhibit substantial variation among different tomato cultivars.…”