Comparison of starch accumulation between the ECMs and wild-type calli. (A) Light microscopic inspection of starch granule deposition in the callus cells. Protoplasts from wild-type calli and representative ECMs, respectively, are observed under a normal light field and a polarization microscope. The polarization microscope shows the characteristic birefringences of starch granules and carotenoid crystals, respectively. (B) Starch content analysis. Columns and bars represent the means and ± SD, respectively (n = 3 technical triplicate experiments). **Indicates that the values are significantly different compared with ECMs at the significance level of P < 0.01. (C) I2/KI staining analysis and isolation of starch granules for SEM inspection. HQC is shown as a representative. The image in the lower left corner shows the yields of starch granules from equal weight of calli. HQC-WT and HQC-2 represent the ECM line and wild type, respectively. The right images show the starch granule morphology magnified 4500 times via SEM.