Ronelie C. Chato-Salvador
Fisheries Department, College of Agriculture, Fisheries and Natural Resources. University of Eastern Philippines, Catarman 6400, Northern Samar, Philippines
The decline in production and quality of Kappaphycus seaweeds reported in the Philippines since 2007 has been attributed to inadequate supply of good quality seedstocks. Traditionally, seedstocks for these species are vegetative parts from previous crops, resulting in deterioration of genetic quality and poor farming performance. Among the strategies pursued to solve the problem is production of improved strains from protoplasts, or living cells devoid of cell walls. However, the use of protoplasts in seedstock production and strain improvement for economically important seaweed Kappaphycus spp, is still not possible due to their low regeneration rate. This study was conducted to optimize conditions for regeneration and growth of protoplasts isolated from Kappaphycus spp. through enzymatic methods. Viable protoplasts from different strains of Kappaphycus alvarezii and Kappaphycus striatus, different tissue types (medullary, cortical) and ages (apical, basal) were isolated using a two-step enzymatic method. The protoplasts were embedded in carrageenan gel droplets and flooded with f/2 medium for 2-3 weeks, and were cultured in lighted shelves at different irradiance levels, at 22+ 20C and 12:12 L:D photoperiod. Protoplasts of subcortical cells obtained from the apical portion of seven farmed and wild strains of K. alvarezii collected from Surigao del Norte and Northern Samar regenerated into 5mm-12mm germlings ( < 1cm plants) after 26-32 days of culture in gel droplets. Regeneration rate was 10-36% and two regeneration patterns were observed, resulting in development of either a dichotomously branched thallus, or a uniseriate, branching filaments in 6 months.