PHYSIOLOGICAL FACTORS THAT AID DIFFERENTIATION OF ZYGOTES AND EARLY JUVENILES OF ACETABULARIA ACETABULUM (CHLOROPHYTA)

Abstract

To improve our understanding of early development and to enable standard genetic analyses in Acetabularia acetabulum (L.) Silva, we examined some physiological factors that impact differentiation of young diploid plants. Eighty percent of zygotes differentiated within 6–7 days when they were inoculated at high densities (≥5,000 zygotes·mL−1), and zygote differentiation was independent of the photon flux density of cool white light. In contrast, 90% of juveniles differentiated within 25 days when they were inoculated at medium densities (<1,000 individuals·mL−1) and required >250 μmol·m−2·s−1 cool white light. Both zygotes and juveniles differentiated best at an alkaline pH (7.96), when the temperature was between 18.6° and 23.5° C, and when the external potassium concentration was 1–10 mM. Compared to prior publications, adjustment of these parameters reduced the time to differentiation by 25% (from 8 to 6 days) and more than tripled the percentage of zygotes that developed into healthy juveniles (from 23% to ∼80%).