A tobacco mutant with a reduced cell number in embryo sacs

Abstract

 The semisterile tobacco plant BG-141.4 was produced using both irradiation with X-rays and anther culture. The embryological investigation of the progeny of this plant following selfing (R1) revealed disturbances in the structure of the mature embryo sacs (ESs). The major abnormality was a decrease in cell number in the ESs. Other abnormalities included disturbances in the distribution of nuclei and in cell differentiation. The overall frequency of abnormal ESs in individual plants investigated varied from 8% to 83%, while the frequency of ESs with a reduced number of cells varied from 5% to 72%. Since the examination of three subsequent generations - R2, R3 and R4 - showed similar results, it is concluded that a mutation has been induced. Its main phenotypic manifestation is most likely related to its lacking one or two nuclear division(s) during the coenocytic stage of megagametogenesis. The penetrance of the mutation varies widely.