TITLE 2,3,5-Triphenyltetrazolium reduction in the viability assay of Ulva fasciata (Chlorophyta) in response to salinity stress
AUTHOR Wan-Chun Chang
Institute of Marine Biology, National Sun Yat-Sen University, Kaohsiung, Taiwan 80424, Republic of China
Ming-Hwa Chen
Institute of Marine Biology, National Sun Yat-Sen University, Kaohsiung, Taiwan 80424, Republic of China
Tse-Min Lee
Institute of Marine Biology, National Sun Yat-Sen University, Kaohsiung, Taiwan 80424, Republic of China
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ABSTRACT The salinity tolerance in a marine green macroalga Ulva fasciata was assessed by the reduction of 2,3,5-triphenyltetrazolium chloride (TTC) to water-insoluble red formazan. Thallus strips of 0.1 gram fresh weight were incubated in 1.5 ml of 50 mM sodium phosphate buffer (pH 7.4) containing TTC, and the formazan extracted by 95% ethanol was measured at 530 nm to avoid pigment interference. The TTC reduction activity reached the maximal level 18 h after incubation in 0.8% TTC solution in the presence of 3% NaCl. Plants of different sizes had similar TTC reduction activity, but activity in the 3-cm-long base near the rhizoidal portion was lower than in the remaining parts (p<0.01). On exposure of whole plants to various salinities, ranging from 5‰ to 150‰, the reduction of TTC in the 2.5 cm tip (the distal end) of the largest thallus peaked in plants grown at 30‰ and was low at salinity above 120‰ or below 5‰. Both the net photosynthetic O2 evolution rate in the 2.5 cm tip of the largest thallus and the specific growth rate (%/d) had similar trends. Compared to plants grown at 30‰, the relative change in TTC reduction activity is associated with the relative change in specific growth rate (r2=0.90) and also with the relative change in net photosynthetic O2 evolution rate (r2=0.93). These results show that Ulva fasciata survives at salinities ranging from 15‰ to 90‰. Tracking relative changes in TTC reduction activity has potential as a tool for predicting salinity tolerance.
KEYWORD Salinity stress; TTC; Ulva fasciata; Viability;
ARTICLE INFO Botanical Bulletin of Academia Sinica, Volume 40 Number 3 July 1999, page 207-212, 6 pages
PUBLISHER Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China