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PubMed | University Pierre and Marie Curie, University of Silesia, University of Nottingham and SABMiller plc. SABMiller House
Type: Journal Article | Journal: Plant biotechnology journal | Year: 2016

Increased tolerance of crops to low oxygen (hypoxia) during flooding is a key target for food security. In Arabidopsis thaliana (L.) Heynh., the N-end rule pathway of targeted proteolysis controls plant responses to hypoxia by regulating the stability of group VII ethylene response factor (ERFVII) transcription factors, controlled by the oxidation status of amino terminal (Nt)-cysteine (Cys). Here, we show that the barley (Hordeum vulgare L.) ERFVII BERF1 is a substrate of the N-end rule pathway in vitro. Furthermore, we show that Nt-Cys acts as a sensor for hypoxia in vivo, as the stability of the oxygen-sensor reporter protein MCGGAIL-GUS increased in waterlogged transgenic plants. Transgenic RNAi barley plants, with reduced expression of the N-end rule pathway N-recognin E3 ligase PROTEOLYSIS6 (HvPRT6), showed increased expression of hypoxia-associated genes and altered seed germination phenotypes. In addition, in response to waterlogging, transgenic plants showed sustained biomass, enhanced yield, retention of chlorophyll, and enhanced induction of hypoxia-related genes. HvPRT6 RNAi plants also showed reduced chlorophyll degradation in response to continued darkness, often associated with waterlogged conditions. Barley Targeting Induced Local Lesions IN Genomes (TILLING) lines, containing mutant alleles of HvPRT6, also showed increased expression of hypoxia-related genes and phenotypes similar to RNAi lines. We conclude that the N-end rule pathway represents an important target for plant breeding to enhance tolerance to waterlogging in barley and other cereals.

Oladokun O.,University of Nottingham | Smart K.,SABMiller Plc SABMiller House | Cook D.,University of Nottingham
Journal of the Institute of Brewing | Year: 2016

A single-run reverse phase-high performance liquid chromatography method for the quantification of humulinones, α-acids, iso-α-acids and reduced iso-α-acids (where present) in commercial beer samples is presented. The method utilizes a binary solvent system consisting of (A) 1% v/v acetic acid and (B) 0.1% v/v orthophosphoric acid in acetonitrile. Separation was achieved on a Purospher® star RP-18 column (250×46mm, 3μm) with a flow rate of 0.5mL/min. The compounds of interest eluted within 32min. The method was fully validated according to International Conference on Harmonization guidelines and subsequently applied to monitor degradation of hop acids in a storage trial where four lager beers were aged at 28 and 38°C for 70 and 60days, respectively. Results confirmed the widely reported degradation through storage of trans-iso-α-acids whilst demonstrating that the HLPC method was sufficiently sensitive to monitor and model this degradation. One beer exhibited a significantly lower (P<0.05) rate of trans-iso-α-acid degradation than the other conventionally hopped beers in the study, which might have been linked to its higher pH (4.71 vs 4.36). The relative stability of reduced iso-α-acids during ageing was also confirmed. © 2016 The Institute of Brewing & Distilling.

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