Data_Sheet_1_Abundance, diversity, and composition of root-associated microbial communities varied with tall fescue cultivars under water deficit.PDF

The plant breeding program has developed many cultivars of tall fescue (Festuca arundinacea) with low maintenance and stress tolerance. While the root-associated microbial community helps confer stress tolerance in the host plant, it is still largely unknown how the microbiota varies with plant cultivars under water stress. The study aimed to characterize drought-responsive bacteria and fungi in the roots and rhizosphere of different tall fescue cultivars. Intact grass-soil cores were collected from six cultivars grown in a field trial under no-irrigation for 3 years. Tall fescue under irrigation was also sampled from an adjacent area as the contrast. Bacterial and fungal communities in roots, rhizosphere, and bulk soil were examined for abundance, diversity, and composition using quantitative-PCR and high-throughput amplicon sequencing of 16S rRNA gene and ITS regions, respectively. Differences in microbial community composition and structure between non-irrigated and irrigated samples were statistically significant in all three microhabitats. No-irrigation enriched Actinobacteria in all three microhabitats, but mainly enriched Basidiomycota in the root endosphere and only Glomeromycota in bulk soil. Tall fescue cultivars slightly yet significantly modified endophytic microbial communities. Cultivars showing better adaptability to drought encompassed more relatively abundant Actinobacteria, Basidiomycota, or Glomeromycota in roots and the rhizosphere. PICRUSt2-based predictions revealed that the relative abundance of functional genes in roots related to phytohormones, antioxidant enzymes, and nutrient acquisition was enhanced under no-irrigation. Significant associations between Streptomyces and putative drought-ameliorating genes underscore possible mechanics for microbes to confer tall fescue with water stress tolerance. This work sheds important insight into the potential use of endophytic microbes for screening drought-adaptive genotypes and cultivars.</p

The heatmap of soil fungal taxa.

The heatmap contained fungal taxa that differed significantly among six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St. Augustinegrass; ZG, zoysiagrass). Only taxa with ≥ 2.5% relative abundance and assigned at least to the phylum level are included. The color scale indicates the relative abundance (%).</p

Results of marginal tests by DistLM.

Results of marginal tests by DistLM.</p

Results of sequential tests with forward selection by DistLM.

Results of sequential tests with forward selection by DistLM.</p

Principal coordinate analysis (PCoA) of soil microbial communities.

Soil bacterial (a, b) and fungal (c, d) communities in six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St. Augustinegrass; ZG, zoysiagrass). Cool- and warm-season turfgrass systems are represented by empty and filled symbols, respectively.</p

Relative abundances of genes involved in soil N processes.

Genes for N transformations were predicted from the bacterial marker gene 16S rRNA using PICRUSt with a sequence depth of 19,890. Arrow thickness is positively related to gene abundances of individual N pathways, and bar height reflects relative gene abundances, which were nomalized to the highest values of indivisual processes among six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St. Augustinegrass; ZG, zoysiagrass). Gene abundances were calculated as: K00260 + K00261 + K00262 for mineralization; ((K10944 + K10945 + K10946)/3 + K10535)/2 for nitrification; (((K00370 + K00371 + K00374 + K00373)/4 + (K02567 + K02568)/2) + (K00362 + K00363)/2 + K03385)/2 for dissimilatory NO3- reduction to NH4+ (DNRA); (K00367 + K00372 + K00360 + K00366)/2 for assimilatory NO3- reduction to NH4+; (K02588+K02586+K02591)/3+K00531 for N fixation; (K00370+K00371+K00374+K00373)/4 +(K02567+K02568)/2 for dissimilatory NO3- reduction to NO2-; K00368 for dissimilatory NO2- reduction to NO; (K04561+K02305)/2 for dissimilatory NO reduction to N2O; K00376 for dissimilatory N2O reduction to N2.</p

Soil microbial alpha diversity metrics (means ± standard errors) in six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St. Augustinegrass; ZG, zoysiagrass), estimated from a sequence depth of 27,000 for bacteria and 25,000 for fungi.

Different letters within each row indicate significant differences at P < 0.05.</p

Selected soil properties (means ± standard errors) in six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St.

Augustinegrass; ZG, zoysiagrass). Different letters within each row indicate significant differences at P < 0.05.</p

Growth habits and defoliation management of six turfgrass species.

Defoliation was more intensive and frequent in green than in non-green turfgrass systems.</p

The heatmap of soil bacterial taxa.

The heatmap contained bacterial taxa that differed significantly among six turfgrass systems (BM, bermudagrass; CB, creeping bentgrass; KB, Kentucky bluegrass; TF, tall fescue; ST, St. Augustinegrass; ZG, zoysiagrass). Only taxa with ≥ 2.5% relative abundance and assigned at least to the phylum level are included. The color scale indicates the relative abundance (%).</p