Electroporation modulates the embryogenic responses of asparagus (Asparagus officinalis L.) microspores

Microspores of three genotypes of Asparagus officinalis L. were mechanically isolated without affecting their viability and were submitted to electric fields in order to modulate their competence for embryogenesis. When a constant pulse length and various field strengths (250, 500, 750, 1000, 1500, and 2000 V/cm) were tested, the viability of electro-treated microspores decreased as the field strength increased, for all genotypes. Conversely, the embryogenic competence was genotype dependent and was enhanced by low voltages for two clones when microspores were cultured in the presence of auxin. When the effect of pulse duration was studied, despite a strong genotype effect on responses, a short pulse coupled with a low voltage appeared to improve the competence for proembryo formation compared with nonelectroporated microspores, while longer pulses significantly improved microspore division.