Streptomycesendophytes promote the growth ofArabidopsis thaliana

Abstract

19 20 21 22 23 101 10% (v/v) glycerol and serial dilutions were spread onto either soya flour mannitol (SFM) agar, 102 starch casein agar, or minimal medium agar containing sodium citrate (Lebeis et al 2015).103Plates were incubated at 30C for up to 14 days. Colonies resembling streptomycetes were re-104 streaked onto SFM agar and identified by 16S rRNA gene PCR amplification and sequencing 105 with universal primers PRK341F and MPRK806R (see Table S1 for primers, plasmids and 106 strains used in this work). Streptomyces strains were maintained on SFM agar (N1, N2, M2, 107 M3 and S. coelicolor M145), Maltose/Yeast extract/Malt extract (MYM) agar with trace 108 5 elements (L2) or ISP2 agar (S. lydicus strains); media recipes are detailed in Table S2. Spore 109 stocks were made as described previously (Kieser et al 2000). 110 111 Genome sequencing and analysis. High quality genome sequences were obtained for newly 112 isolated strains N1, N2, M2, M3, and L2, as well as three known strains of Streptomyces 113 lydicus; one isolated from the commercial plant growth-promoting product Actinovate and two 114 additional S. lydicus strains (ATCC25470 and ATCC31975) obtained from the American Type 115 Culture Collection. Strains were sequenced using PacBio RSII sequencing technology at the 116 131 isolated from a patient at the Norfolk and Norwich University Hospital UK (Qin et al 2017), 132Escherichia coli and Pseudomonas syringae DC3000 were grown overnight in 10 ml Lysogeny 133 Broth (LB) (1% tryptone, 0.5% NaCl, supplemented with 0.1% glucose for P. syringae). These 134 were sub-cultured 1 in 20 (v/v) for a further 4 hours at 30°C for P. syringae and 37°C for E. 135 coli. These cultures were then used to inoculate 100 ml of molten LB (0.5% agar, plus 0.1% 136 glucose for P. syringae), of which 3 ml was used to overlay agar plates containing Streptomyces 137 colonies. Plates were incubated for 48 hours at 30C, and bioactivity was indicated by a clear 138 halo around the Streptomyces colony. For bioassays using the fungal strains Lomentospora 139 prolificans or Gaeumannomyces graminis, Streptomyces species were grown for 7 days, and 140 then a plug of the fungus (grown on potato glucose agar, Sigma Aldrich, for 14 days) was 141

The cellular response towards lanthanum is substrate specific and reveals a novel route for glycerol metabolism inPseudomonas putidaKT2440

“…The previously reported fertilizing effect of REEs on different food crops could hence be partially the result of increased competitiveness of plant growth promoting organisms such as P. putida during root colonization. This hypothesis is further supported by a recent study, which found that Pseudomonads predominantly thrive on root exudates in vivo and are hence enriched in the rhizosphere of Arabidopsis thaliana (10). As such, it will be interesting to see what future research will add to the currently emerging theme of REEs being an important micronutrient for methylotrophic and non-methylotrophic organisms.…”

“…Its diversity is mainly shaped by root exudates, a complex mixture of organic compounds including carbohydrates, amino acids, or carbon acids (4, 5) and plant-, fungal-, and bacteria-derived volatiles (VOCs) such as alkenes, alcohols, terpenes or benzenoids (6, 7). As such, it is not surprising that the soil-dwelling organism P. putida KT2440 is equipped with a broad diversity of metabolic pathways in order to maximize its cellular fitness in different environmental niches including the rhizosphere (8–10). For efficient growth on various alcoholic VOC substrates, it uses a periplasmic oxidation system consisting of the pyrroloquinoline quinone-dependent alcohol dehydrogenases (PQQ-ADHs) PedE and PedH (11, 12).…”

The Cellular Response to Lanthanum Is Substrate Specific and Reveals a Novel Route for Glycerol Metabolism in Pseudomonas putida KT2440

“…Hence, the previously reported fertilizing effect of REEs on different food crops (34)(35)(36)(37)(38) could be a consequence of increased competitiveness of plant growth-promoting organisms such as P. putida during root colonization. This hypothesis is supported by a recent study which found that pseudomonads thrive predominantly on root exudates in vivo and are hence enriched in the rhizosphere of Arabidopsis thaliana (10). As such, it will be interesting to see what future research will add to the currently emerging theme of REEs being important micronutrients for methylotrophic and nonmethylotrophic organisms, in particular in regard to bacterium-plant interactions.…”

“…Its diversity is predominantly shaped by root exudates, a complex mixture of organic compounds, including carbohydrates, amino acids, or carbon acids (4,5) and plant-, fungus-, and bacterium-derived volatiles (VOCs) such as alkenes, alcohols, terpenes, or benzenoids (6,7). As such, it is not surprising that the soil-dwelling organism Pseudomonas putida KT2440 is equipped with a broad diversity of metabolic pathways to maximize its cellular fitness in different environmental niches (8)(9)(10). For efficient growth on various alcoholic VOC substrates, P. putida uses a periplasmic oxidation system consisting of the pyrroloquinoline quinone-dependent alcohol dehydrogenases (PQQ-ADHs) PedE and PedH.…”

Investigating the Role of Root Exudates in Recruiting Streptomyces Bacteria to the Arabidopsis thaliana Microbiome

“…440 million years ago shortly after plants began to colonize land and it has been suggested that their filamentous growth and diverse secondary metabolism may have evolved to enhance their ability to colonize plant roots ( Chater, 2016 ). Several studies have reported that streptomycetes are abundant inside the roots of the model plant Arabidopsis thaliana ( Bulgarelli et al, 2012 ; Lundberg et al, 2012 ; Schlaeppi et al, 2014 ; Bai et al, 2015 ; Carvalhais et al, 2015 ) where they can have beneficial effects on growth ( Worsley et al, 2020 ) while others have shown that streptomycetes can protect crop plants such as strawberry, lettuce, rice and wheat against biotic and abiotic stressors, including drought, salt stress, and pathogenic infection ( Viaene et al, 2016 ; Newitt et al, 2019 ). However, different plant genotypes are associated with distinctive root-associated microbial communities and not all plant species enrich streptomycetes in their roots, a notable example being barley ( Bulgarelli et al, 2015 ).…”