Effects of Chromium VI stress on green alga Ulva lactuca (L.)

Authors: DİLEK ÜNAL, NURAY O. IŞIK, ATAKAN SUKATAR

Abstract: In order to contribute to the understanding of its response to metal stress, Ulva lactuca (L.) was treated with different concentration of chromium (VI) (0.2, 0.5, 1, and 5 mM K2CrO4), and alterations in Fv/Fm ratio (maximal photochemical efficiency of PSII) and cell viability were investigated. Significant alterations of the maximal photochemical efficiency of PSII (Fv/Fm) ratio were observed in response to the increase in chromium concentration. The Fv/Fm ratio decreased in Ulva lactuca following 2 h treatment with 1 and 5 mM Cr(VI) solution. The cell viability was decreased in cells exposed to higher Cr(VI) concentrations. Thallus cell morphology was altered in thalli exposed to chromium. A cytotoxic effect of chromium was demonstrated for the first time using acridine orange/ethidium bromide staining in macroalgae. In 1 and 5 mM of Cr(VI) treated samples, the rate of necrotic cells increased about 76.93% and 84.23%, respectively.

Keywords: Chromium VI, photosynthesis, Ulva lactuca, acridine orange/ethidium bromide staining

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