Uv 1700 uv visible spectrophotometer

GsPs was selected as the control, 200 μL of GsPs solution of different concentrations was added into a glass test tube, followed by 7500 μL of HCl-n-butanol solution (with a volume ratio of 5:95) and 100 μL of 2% ammonium ferric sulfate solution (2 M HCl as the solvent). After fully mixing, the test tube was placed in boiling water for 75 min and then cooled by ice bath immediately. When the temperature was restored to room temperature, the absorbance value at 550 nm (A₅₅₀) was measured on a UV-1700 UV-Visible Spectrophotometer (Shimadzu, Kyoto, Japan) with distilled water as blank. The standard curve was drawn with the concentration of GsPs as the X-axis and the absorbance as the Y-axis, and the linear regression equation Y = 0.9933X − 0.0045 (R² = 0.9998) was obtained, with the linear range of 0.00–1.00 mg/mL. The solution of each sample was diluted with methanol to their appropriate concentration so that the absorbance value at 550 nm was between 0.200 and 0.800. The A₅₅₀ value of each sample was determined respectively, and the TOPCs of each sample were calculated according to the linear regression equation and expressed as the equivalent value of each sample to GsPs (mg GsPs/g DW) [36 (link),37 (link)].

Pigments were extracted from 0.2 g fresh leaves with 80% acetone followed by 48 h of incubation in dark at 4 °C. The contents of photosynthetic pigments including Chl and carotenoid (Caro) were determined with UV-1700 UV–visible spectrophotometer (Shi-madzu) at 663 nm, 646 nm and 470 nm, and were calculated by using the equations described by Lichtenthaler and Wellburn [45 (link)].
Chl used for HPLC analysis were extracted from fresh rice leaf tissue at the three-leaf stage with 100% acetone by centrifuging at 7197 g (Eppendorf 5430R; 7830 rpm) for 15 min. The supernatants filtered with 0.22 μm membrane were subjected to HPLC on a C18 column (Eclipse XDB-C18, 4.6 mm i.d. × 150 mm, 5 μm; Agilent). The mobile phase was solvent containing methanol, acetonitrile and acetone (1:3:1 v:v:v) at a flow-rate of 1.0 mL min^− 1 at 40 °C [46 (link)]. Elution profiles were monitored at 660 nm.

Chls were extracted from 0.2 g fresh leaves of the 502ys mutant and its wild-type Nipponbare with 80% acetone, and Chl contents were determined with UV-1700 UV-visible spectrophotometer (Shimadzu) according to the method of Arnon (1949 (link)).
Chls used for HPLC analysis were extracted from fresh rice leaf tissue of four-week-old 502ys and wild-type plants with 100% acetone. The extract was centrifuged at 7,197 g (Eppendorf 5430R; 7,830 rpm) for 15 min, and the supernatants were subjected to HPLC on a C18 column (Eclipse XDB-C18, 4.6 mm i.d. × 150 mm long, 5 μm; Agilent) and eluted with solvent (methanol: acetonitrile: acetone = 1:3:1) at a flow-rate of 1.0 mL min⁻¹ at 40°C, as previously described (Zapata et al. 2000 (link);Nakanishi et al. 2005 (link);Tanaka et al. 1999 (link)2010 (link);Zhou et al. 2013 (link)). Elution profiles were monitored by measuring A₆₆₀, and Chl a and b standards (Sigma) were used as control.