Microsporogenesis Abortion in Cytoplasmic Male Sterile Plants from H. petiolaris or H. petiolaris fallax Crossed by Sunflower (Helianthus annuus)

The microsporogenesis of two sunflower lines carrying two differentcytoplasmic male sterilities (CMS) from H. petiolaris (PL) andfrom H. petiolaris fallax (PF) has been studied and comparedto the normal process in male fertile lines. The first signsof abortion are, respectively, the vacuolation of the endoplasmicreticulum in PL during the first division of meiosis and theabnormal deposition of the endexine layer in PF during the vacuolationof the microspore. The genotype of the male line seems to modulate the stage ofpollen abortion, Furthermore, two ways of abortion have beenobserved for a single male sterile plant. Consequently, we suggestthat the ultrastructural observations reflect only the mainconsequences of a primary unknown event which takes place earlier. Cytoplasmic male-sterility, meiosis, Helianthus annuus L, H. petiolaris Nutt, microsporogenesis, electron microscopy