Nucleolar Persistence in Meristems of Mung Bean

Abstract

SUMMARYPersistent nucleoli in mitotic cells of primary root, secondary root, and shoot apical meristems of mung bean (Phaseolus aureus Roxb.) were quantified in plants of 4, 8, and 14 days of age. There was no statistical difference in the percentage of persistent nucleoli in primary roots (81.5–89.4%) and secondary roots (82.490.1%). Shoot apical meristems had 6.1–8.3% persistent nucleoli at metaphase, a significantly lower percentage of persistent nucleoli than root meristems. These results parallel other variations between nuclei of shoot and root meristems. Persistent nucleoli of 4- day- old primary root meristems stained positively with silver nitrate. Although this technique has been used as an indication of synthetically active nucleoli, ultrastructural evidence in mung bean indicates that persistent nucleoli are structurally different than synthetically active interphase nucleoli. Thus, means other than silver nitrate staining, should be used to indicate synthetically active nucleoli.