Fungal Endophytes in Aboveground Tissues of Desert Plants: Infrequent in Culture, but Highly Diverse and Distinctive Symbionts

Abstract

In hot deserts, plants cope with aridity, high temperatures, and nutrient-poor soils with morphological and biochemical adaptations that encompass intimate microbial symbioses. Whereas the root microbiomes of arid-land plants have received increasing attention, factors influencing assemblages of symbionts in above-ground tissues have not been evaluated for many woody plants that flourish in desert environments. We evaluated the diversity, host affiliations, and distributions of endophytic fungi associated with photosynthetic tissues of desert trees and shrubs, focusing on non-succulent woody plants in the species-rich Sonoran Desert. To inform our strength of inference, we evaluated the effects of two different nutrient media, incubation temperatures, and collection seasons on the apparent structure of endophyte assemblages. Analysis of >22,000 tissue segments revealed that endophytes were isolated four times more frequently from photosynthetic stems than leaves. Isolation frequency was lower than expected given the latitude of the study region, and varied among species a function of sampling site and abiotic factors. However, endophytes were very species-rich and phylogenetically diverse, consistent with less-arid sites of a similar latitudinal position. Community composition differed among host species, but not as a function of tissue type, sampling site, sampling month, or exposure. Estimates of abundance, diversity and composition were not influenced by isolation medium or incubation temperature. Phylogenetic analyses of the most commonly isolated genus (Preussia) revealed multiple evolutionary origins of desert-plant endophytism and little phylogenetic structure with regard to seasonality, tissue preference, or optimal temperatures and nutrients for growth in vitro. Together, these results provide insight into endophytic symbioses in desert plant communities, and can be used to optimize strategies for capturing endophyte biodiversity at regional scales.

An epigenetic modifier induces production of (10′ S )-verruculide B, an inhibitor of protein tyrosine phosphatases by Phoma sp. nov. LG0217, a fungal endophyte of Parkinsonia microphylla

“…One fungus of interest was used for the present study: isolate LG0217, which has been deposited at the Robert L. Gilbertson Mycological Herbarium with accession number LG0217. Total genomic DNA was extracted from fresh mycelium 32 and the internal transcribed spacers and 5.8S gene (ITSrDNA) was amplified and sequenced by PCR. 32 The ITSrDNA sequence was compared against the GenBank database using BLAST.…”

“…Total genomic DNA was extracted from fresh mycelium 32 and the internal transcribed spacers and 5.8S gene (ITSrDNA) was amplified and sequenced by PCR. 32 The ITSrDNA sequence was compared against the GenBank database using BLAST. 33 The top BLAST matches were to unnamed fungi isolated from other desert plants, 32 with several species of Phoma and allied taxa that were studied by Davey and Currah.…”

“…32 The ITSrDNA sequence was compared against the GenBank database using BLAST. 33 The top BLAST matches were to unnamed fungi isolated from other desert plants, 32 with several species of Phoma and allied taxa that were studied by Davey and Currah. 34 We therefore downloaded the alignment published by Davey and Currah, 34 trimmed it to include closely related taxa that were readily alignable with LG0217, and integrated two representative sequences.…”

“…34 We therefore downloaded the alignment published by Davey and Currah, 34 trimmed it to include closely related taxa that were readily alignable with LG0217, and integrated two representative sequences. 32 The resulting alignment consisted of species of Phoma, Ascochyta, Didymella, and Westerdykella (outgroup), for a total of 24 ingroup taxa and one outgroup taxon. The data set was aligned automatically using MUSCLE (http://www.ebi.ac.uk/Tools/msa/muscle/) with default parameters and verified by eye prior to analysis.…”

Specificity of root microbiomes in native‐grown Nicotiana attenuata and plant responses to UVB increase Deinococcus colonization

“…Interestingly, Preussia is among the most prominent fungal endophytes in above‐ground tissues of nonsucculent desert plants (Massimo et al . ), while in the succulent Cactus species Opuntia robusta Prathoda was dominant (Fonseca‐García et al . ).…”