Amberlite ira 743

Hydrochloric acid (Guaranteed Reagent) was redistilled in a sealed vessel to remove the exogenous B. The cesium carbonate (spectroscopic pure) was of 99.994% purity. High-purity graphite was added to a mixture of ethanol solution (80%) to obtain the final solution corresponding to 13 mg/g graphite. The isotopic reference standard used in this study was NIST SRM 951 boric acid (Gaithersburg, MD, USA). A solution of mannitol of 1.82% (w/v) and Cs₂CO₃ solution containing 12.3 mg/mL of Cs⁺ was also prepared. Sodium carbonate, ammonia hydroxide, and sodium chloride were of the analytical grade reagent. Borax and boric acid were of Guaranteed grade Reagent.
The resins, B specific resin Amberlite IRA 743, strong cation exchange resin Dowex 50W X8, and weakly anion exchange resin Amberlite IRA 67, were purchased from Sigma-Aldrich Co. LLC, China.
High purity water with a B blank less than 0.008 μg was redistilled by subboiling distillation and passed through a resin column filled with B specific resin (Amberlite IRA 743), which was used to prepare the standard solution and working solution.
An inductively coupled plasma optical emission spectrometer (ICP-OES, Vista MPX, Varian, USA) with a 40 MHz radio frequency generator and a charge coupled device detector (Vista Chip) was used to detect B.

To induce B deficiency, T2 plants were germinated on half‐strength MS medium (2.2 g/L MS salts with minimal organics [Duchefa], 1% sucrose, 0.7% Phytagel [Sigma], pH 5.8 [KOH]) containing the respective antibiotic. After 1 week, the plantlets were transferred to B deficiency medium (625 μM KH₂PO₄, 750 μM MgSO₄, 1.5 mM CaCl₂, 9.4 mM KNO₃, 1 mM NH₄NO₃, 75 μM FeNa₂EDTA, 0.055 μM CoCl₂, 0.05 μM CuSO₄, 50 μM MnSO₄, 0.5 μM Na₂MoO₄, 15 μM ZnSO₄, 2.5 μM KI, 1 mM MES, pH 5.5 [KOH], 1% Phytagel). The B deficiency medium was treated with MQ‐washed 3 g/L Amberlite IRA‐743 (Sigma) overnight prior to autoclaving. After 7 days of growth, roots were harvested for RNA extraction.

The AIR was de-esterified in 1.0 m Na₂CO₃ (pH ≈ 11.5) at 4 °C for 16 h, then adjusted to pH 4.5 with acetic acid, rinsed with water followed by acetone, and dried. The solid material was digested with endo-polygalacturonase [EPG; 5 U mL^–1; from Aspergillus aculeatus; Megazyme, http://www.megazyme.com; pre-dialysed against pyridine/acetic acid/water (1 : 1 : 98)] at 20 °C for 16 h. All water used for these treatments had been freed of soluble boron compounds on Amberlite IRA743 (Sigma, https://www.sigmaaldrich.com/). Portions of the digest were analysed by thin-layer chromatography (TLC) and PAGE.