Table_1_Bacterial Production of Indole Related Compounds Reveals Their Role in Association Between Duckweeds and Endophytes.XLSX

<p>Duckweed farming can be a sustainable practice for biofuel production, animal feed supplement, and wastewater treatment, although large scale production remains a challenge. Plant growth promoting bacteria (PGPB) have been shown to improve plant health by producing phytohormones such as auxin. While some of the mechanisms for plant growth promotion have been characterized in soil epiphytes, more work is necessary to understand how plants may select for bacterial endophytes that have the ability to provide an exogenous source of phytohormones such as auxin. We have isolated and characterized forty-seven potentially endophytic bacteria from surface-sterilized duckweed tissues and screened these bacterial strains for production of indole related compounds using the Salkowski colorimetric assay. Indole-3-acetic acid (IAA), indole-3-lactic acid (ILA), and indole produced by various bacterial isolates were verified by mass spectrometry. Using the Salkowski reagent, we found that 79% of the isolated bacterial strains from our collection may be capable of producing indole related compounds to various extents during in vitro growth. Of these bacteria that are producing indole related compounds, 19% are additionally producing indole. There is an apparent correlation between the type of indole related compound produced by a particular bacteria and the duckweed genus from which the bacterial strain is derived. These results suggest the possible association between different duckweed genera and endophytes that are producing distinct types of secondary metabolites. Understanding the role of indole related compounds during interaction between endophytes and the plant host may be useful to help design synthetic bacterial communities that could target specific or multiple species of duckweed in the future to sustainably enhance plant growth.</p

Image_1_Bacterial Production of Indole Related Compounds Reveals Their Role in Association Between Duckweeds and Endophytes.PDF

<p>Duckweed farming can be a sustainable practice for biofuel production, animal feed supplement, and wastewater treatment, although large scale production remains a challenge. Plant growth promoting bacteria (PGPB) have been shown to improve plant health by producing phytohormones such as auxin. While some of the mechanisms for plant growth promotion have been characterized in soil epiphytes, more work is necessary to understand how plants may select for bacterial endophytes that have the ability to provide an exogenous source of phytohormones such as auxin. We have isolated and characterized forty-seven potentially endophytic bacteria from surface-sterilized duckweed tissues and screened these bacterial strains for production of indole related compounds using the Salkowski colorimetric assay. Indole-3-acetic acid (IAA), indole-3-lactic acid (ILA), and indole produced by various bacterial isolates were verified by mass spectrometry. Using the Salkowski reagent, we found that 79% of the isolated bacterial strains from our collection may be capable of producing indole related compounds to various extents during in vitro growth. Of these bacteria that are producing indole related compounds, 19% are additionally producing indole. There is an apparent correlation between the type of indole related compound produced by a particular bacteria and the duckweed genus from which the bacterial strain is derived. These results suggest the possible association between different duckweed genera and endophytes that are producing distinct types of secondary metabolites. Understanding the role of indole related compounds during interaction between endophytes and the plant host may be useful to help design synthetic bacterial communities that could target specific or multiple species of duckweed in the future to sustainably enhance plant growth.</p

File 3: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Isochron and weighted mean plots for the Lu–Hf matrix-correction standard (OD-306) and secondary standards HR-1 and Bamble-1. MSWD, mean squared weighted deviation; n, number of analyses; P(χ2), Chi-squared probability for a single data population. Where required (i.e. insufficient spread along the isochron), the isochrons were anchored to an initial 177Hf/176Hf ratio of 3.55 ± 0.05 (see text)

File 4: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Zircon U–Pb isotope data for the Reynolds–Anmatjira Range samples as well as for the U–Pb standards. Rho, error correlation

File 7: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Ti-in-Quartz analytical results. Temperatures were calculated using the formula in Wark and Watson (2006)

File 10: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Full Concordia plots for the zircon U–Pb data from the Reynolds–Anmatjira samples. The age calculation is based on the youngest concordant grains (green symbols) only. MSWD, mean squared weighted deviation; P(χ2), Chi-squared probability for a single data population

File 1: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Concordia and weighted mean U–Pb plots for the secondary zircon, apatite, monazite and titanite standards. MSWD, mean squared weighted deviation; n, number of analyses

File 5: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Apatite, monazite and titanite U–Pb and trace element data for all analysed samples (tab names refer to the four study areas), including data for the analytical standards. Rho, error correlation. All trace element data are reported in ppm concentrations. Log(LREE), logarithm of the sum of the La, Ce, Pr and Nd concentrations, which was used to distinguish age populations (see text)

File 2: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Analytical conditions for the Lu–Hf and Ti-in-quartz laser sessions (named after the four study areas for this paper). *Laser spot diameters for standards are given within brackets

File 9: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

Thin section microphotographs from the Taratap Granodiorite. (A) Apatite cogenetic with allanite. (B) Apatite overgrown by monazite. (C, D) Titanite in chlorite ((C) transmitted light image; (D) reflective light image; circle symbols are laser ablation spots)