Quantitative viability of seaweed tissues assessed with 2,3,5-triphenyltetrazolium chloride

Abstract

A spectrophotometric quantification method was optimized to evaluate its utility in seaweed tissue viability tests using the enzymatic reduction of colorless 2,3,5-triphenyltetrazolium chloride (TTC) to a colored triphenylformazan (TPF). To allow accurate determination of TPF in the seaweed Porphyra thallus and conchocelis, 0.2 g of tissues are incubated with 4 mL of 0.8% TTC reagent in the dark at 20°C for 1 h under a mineral oil layer. The TPF formed in tissues was extracted for 15 min at 60°C with 2 mL of 0.2 N KOH in 25% ethanol. Then TPF is partitioned away by prompt addition of hexane and vortexing. By this procedure, we have observed nearly complete separation of TPF, and observed good spectrophotometric discrimination between TPF and other hexane-soluble pigments at 545 nm. This procedure has proved applicable to a wide range of seaweed taxa; 1 species of Chlorophyta, 4 species of Phaeophyta and 7 species of Rhodophyta tested.