Fig. 4
The distribution of starch granules in internodes with different developmental degree in 0.5- (a-e) and 1-month-old (f) shoots. Light micrographs. Mx Metaxylem, Ph pholem. a The longitudinal section of the internode in the top portion, showing more starch granules in node than in internode and the differentiation of vessels (arrow). Bar = 40 μm. b Lots of starch granules around the nuclei in node of top portion (arrow). Bar = 10 μm. c The transverse section of the 5th internode above ground (internode 5), showing abundant of starch granules in parenchyma cells around the fiber bundles. Bar = 20 μm. d The transverse section of the 3rd internode above ground (internode 3), showing the decrease of starch granules (arrow) in parenchyma cells between metaxylem and phloem. Bar = 20 μm. e The transverse section of the 1st internode above ground (internode 1), showing that only several starch granules were left close to the cell wall. Bar = 10 μm. f The longitudinal sections of the 1st internode of 1-month-old shoot (elongation completed and maturing, labeled as M1), showing that a few starch granules (arrow) could still be observed in those parenchyma cells close to metaxylem vessels. Bar = 10 μm