Diversity of fungal endophytes in recent and ancient wheat ancestorsTriticum dicoccoidesandAegilops sharonensis

Abstract

Endophytes have profound impacts on plants, including beneficial effects on agriculturally important traits. We hypothesized that endophytes in wild plants include beneficial endophytes that are absent or underrepresented in domesticated crops. In this work, we studied the structure of endophyte communities in wheat-related grasses, Triticum dicoccoides and Aegilops sharonensis, and compared it to an endophyte community from wheat (T. aeastivum). Endophytes were isolated by cultivation and by cultivation-independent methods. In total, 514 intergenic spacer region sequences from single cultures were analyzed. Categorization at 97% sequence similarity resulted in 67 operational taxonomic units (OTUs) that were evenly distributed between the different plant species. A narrow core community of Alternaria spp. was found in all samples, but each plant species also contained a significant portion of unique endophytes. The cultivation-independent analysis identified a larger number of OTUs than the cultivation method, half of which were singletons or doubletons. For OTUs with a relative abundance >0.5%, similar numbers were obtained by both methods. Collectively, our data show that wild grass relatives of wheat contain a wealth of taxonomically diverse fungal endophytes that are not found in modern wheat, some of which belong to taxa with known beneficial effects.

Understanding and exploiting plant beneficial microbes

“…However, metagenomic datasets from different rhizospheres exhibit little overlap in plant-enriched functions [13,15]. On the other hand, plant-associated microbiomes contain a relatively high cultivable fraction of microbes, particularly bacteria [16–19]. It is therefore feasible in plant microbiome research to mitigate the limitations of culture independent methods by generating and studying taxonomically and functionally representative culture collections from plant-associated habitat.…”

“…The definition of large scale, in fact, has changed rapidly from hundreds [16] to tens of thousands [20] of strains. Recent plant-associated bacterial and fungal isolate collections (summarized in Table 1) are derived from sugarcane [20]; grapevine [21–23]; potato [24]; tomato [25]; eucalyptus [25]; rice [26,27]; ancient wheat ancestors [19]; lettuce [28]; Arabidopsis [16, 29]; poplar [29]; and from plants growing in an arsenic-contaminated soils [30]. The increasing volume of isolate collections will tax existing repositories; yet the genomic diversity contained in the bacterial isolates that are being obtained is not nearing saturation [16].…”

Endophytes from wild cereals protect wheat plants from drought by alteration of physiological responses of the plants to water stress

“…In previous work, we profiled fungal endophytes that were isolated from wheat ancestral species A. sharonensis and T. diccocoides and compared them with endophytes from bread wheat (Ofek-Lalzar et al, 2016). Because cultivated wheat has a relatively narrow genetic background and is grown in better conditions than wild species, we hypothesized that endophytes that assist wild plants to survive in natural habitats might be absent or less abundant in cultivated wheat.…”

“…In a previous study, we characterized endophyte communities in two wheat ancestral species, Aegilops sharonensis (Sharon goatgrass) and Triticum diccocoides (wild emmer wheat), and compared them with endophytes found that were found in Triticum aestivum L (bread wheat) cultivar (Ofek‐Lalzar et al ., ). Here, we describe further analyses of two endophytes from this study, which were found in A. sharonensis .…”

“…Although some have beneficial functions (Rodriguez et al, 2009;Busby et al, 2016;Zheng et al, 2016), the vast majority of newly discovered fungal endophytes have not been associated with a specific impact on the host plants and are typed as commensals (Hardoim et al, 2015). A study of fungal endophytes in wild ancestors of wheat revealed species that were not found in the studied wheat cultivar; however, no Epichloë endophytes have been shown to colonize wheat or related plant species (Ofek-Lalzar et al, 2016). This is in line with previous reports that Epichloë species in Triticeae were found only in Hordeum sp.…”