Formation of multiple embryo-like structures from single microspores during maize anther culture.

In a previous study on the RFLP analysis of the maize anther culture response (Wan et al. 1992), some of the anther-derived callus Unes from hybrids H99 x Pa91 (HP) and H99 x FR16 (HF) showed the same RFLP patterns with 58 (for HP Unes) or 35 (for HF lines) RFLP markers used. Since the callus Unes with the identical RFLP pattern were initiated from individual embryo-like structures (ELSs) from the same anther culture plate, these must have originated from the same microspore. Twin embryos which apparently had originated from the same microspore were also observed. Thus in certain cases one microspore must be capable of forming more than one ELS. However, in the case of the callus Unes from a different F1 hybrid (Pa91 x FR16), no identical RFLP patterns were observed. Thus multiple ELS formation from a single microspore may be genetically controlled. Since in some cases the proportion of callus lines resulting from multiple ELS formation can be quite high (about 50% for the HP lines), estimates of gene segregation and anther culture response frequencies can be affected greatly.