Electron-microscopic study of microsporogenesis in male-sterile and male-fertile grain amaranth (Amaranthus hypochondriacus L.)

Abstract

A comparative study of microsporogenesis in male-sterile and male-fertile grain amaranth was conducted using electron-microscopy.The onset of microsporogenesis breakdown in male-sterile is at the mononuclear pollen stage following the release of microspores from tetrads.Abnormality in the behavior of degenerated tapetum was observed, which failed to envelope individual microspores after their release, leading to an abnormal vacuolation in the mononuclear pollen grains.As a result, the normal thickening of pollen wall could not occur and pollen grains could not engorge, causing male sterility.