Determination of <13>^C content in starch from paddy rice plants using stable isotope ratio mass spectrometry(Plant Nutrition)

概要

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A new pretreatment method was developed to purify a starch hydrolysis mixture for isotope ratio mass spectrometry (IRMS) analysis. Ethanol-soluble (EtS) substances were removed from fine rice plant powder. Then, ethanol-insoluble solids were boiled with 10mL of 2.5 mmol L^<-1> H_2SO_4 for 1h and incubated with glucoamylase (from Aspergillus niger) at 52℃ for 24h to hydrolyze and convert to glucose. An acidified glucose-enzyme mixture was purified using serial cartridge solid-phase extraction (SPE), cation exchange resin and non-polar sorbent. This procedure aimed to purify glucose by removing considerable cationic and non-polar substances from the mixtures. The columns were rinsed with 2mL of purified water. The eluate was regarded as the glucose fraction. The overall recovery examined using a rice sample with the addition of <13>^C glucose was 96.3%. This method was used to analyze <13>^C in plants that were fed with <13>^CO_2 on the 14th day after heading time. At the end of <13>^CO_2 feeding, 50% of newly fixed carbon was accumulated in superior leaves, mainly as EtS substances. At grain maturation, 95% of <13>^C was present in grains, 63% of which was in starch.
一般社団法人日本土壌肥料学会の論文