Identification of Duplicate Loci and Evidence for Post-meiotic Gene Expression in Pollen

Abstract

Male and female gametophytes represent a crucial portion of the life cycle in plants. In gymnosperms and angiosperms such stages are highly specialized and relatively brief; however, other tracheophytes possess a more developed gametophyte which often exists as a free-living entity. One would expect such gametophytes to express all enzymes required for an autotropic existence. Indeed, isozyme studies on ferns (Gastony and Gottlieb, 1982) have demonstrated that many of the enzymes of intermediate metabolism are present in gametophytes and that these were synthesized by gametophytic tissue. Parallel investigations on conifers and herbaceous angiosperms have produced similiar results (O’Malley et al., 1978; Weeden and Gottlieb, 1979; Mulcahy et al., 1979, 1981; Adams and Joly, 1980; Tanksley et al., 1981). It appears that, for many vascular plants, approximately 60% of the genes expressed in the sporophyte are also expressed during the gametophytic stage.