Anther wall development, microsporogenesis and microgametogenesis in male fertile and sterile chrysanthemum (Chrysanthemum morifolium Ramat., Asteraceae)

Anther wall development, microsporogenesis and microgametogenesis were compared between a normal male fertile chrysanthemum cultivar 'NJAU04-29-2 and the two male sterile selections 'rm20-11' (anther indehiscent) and 'NJAU05-52-2' (anther aborted). In both of the two male sterile types, the tapetum enlarged abnormally and showed signs of disorganization of walls at the onset of meiosis, the pollen was aborted, the anthers appeared shrunken, and the anther vascular bundle and connective tissue were degenerated by anthesis. In 'rm20-11', the two smaller pollen sacs began to degenerate at the microsporogenesis stage, so that only one or two microsporangia developed, while in 'NJAU05-52-2', only one or two microsporangia were formed following the archesporial cell stage, and most of the microspore mother cells degenerated during the course of meiosis. (C) 2010 Elsevier B.V. All rights reserved.