COMPARISON OF DEVELOPMENT AND PHOTOSYNTHETIC GROWTH FOR FILAMENT CLUMPS AND REGENERATED MICROPLANTLET CULTURES OF AGARDHIELLA-SUBULATA (RHODOPHYTA, GIGARTINALES)

Two axenic, in vitro liquid suspension cultures were established for A gardhiella subulata (C. Agardh) Kraft et Wynne, and their growth chara cteristics were compared. This study illustrated how reliable routes f or the development of suspension cultures of macrophytic red algae of terete thallus morphology can be achieved for biotechnology applicatio ns. Undifferentiated filament clumps of 2-8 mm diameter were establish ed by induction of callus-like tissue from thallus explants, and light ly branched microplantlets of 2-10 mm length were established by regen eration of filament clumps. The filament clumps were susceptible to re generation. Adventitious shoot formation was reliably induced from 40% to 70% of the filament clumps by gentle mixing at 100 rev min(-1) on an orbital shaker. The specific growth rate of the microplantlets was higher than the filament clumps in nonagitated well plate culture (4%- 6% per day for microplantlets vs. 2%-3% per day for filament clumps) a t 24 degrees C and 8-36 mu mol photons.m(-2).s(-1) irradiance (10:14 h LD cycle) when grown on ASP12 artificial seawater medium at pH 8.6-8. 9 with 20%-25% per day medium replacement. Oxygen evolution rate vs. i rradiance measurements showed that relative to the filament clumps, mi croplantlets had a higher maximum specific oxygen evolution rate (P-o, P-max = 0.181 +/- 0.035 vs. 0.130 +/- 0.023 mmol O-2.g(-1) dry cell ma ss.h(-1)), but comparable respiration rate (Q(o) = 0.040 +/- 0.013 vs. 0.033 +/- 0.017 mmol O-2.g(-1) dry cell mass.h(-1)), compensation poi nt (I-c = 3.8 +/- 2.4 vs. 5.7 +/- 1.2 mu mol photons.m(-2).s(-1)), and light intensity at 63.2% of saturation (I-k = 17.5 +/- 3.9 vs. 14.9 /- 2.6 mu mol photons.m(-2).s(-1)). The microplantlet culture was more suitable for suspension culture development than the filament clump c ulture because it was morphologically stable and exhibited higher grow th rates.