Physiological and molecular response of Padina pavonica (Phaeophyta) brown alga towards cadmium heavy metal

Physiological and molecular response of Padina pavonica (phaeophyta) marine alga exposed to different cadmium (0, 2.5, 5 and 10 mg/L) concentrations after 4 days of exposure has been investigated. Physiological data revealed decrease in specific growth rate (SGR%), pigments (Chlorophyll a & b , total chlorophyll and total carotendois) content, osmotic potential with increased electric conductivity (EC) under Cd applied concentrations in the studied alga species. Whereas, carotendois pigments content increased in P. pavonica alga as Cd applied concentrations increased. As for molecular test, RAPD marker has been applied, a decrease in polymorphic bands (PB) from 95 to 87 has been recorded when applied Cd concentration increased from 2.5 to 10 mg/L. Whereas, genomic template stability (GTS%) as a qualitative measurement reflect DNA changes induced by Cd treatment was displayed by RAPD marker. Molecular study revealed increased GTS% value from 30.7 to 42.7% when applied Cd concentration increased from 2.5 to 10 mg/L. Based upon observed physiological (significant increase in carotendois content) and molecular data (decrease in the new induced bands number and increase in disappeared bands as Cd concentration increased from 2.5 to 10 mg/L) in P. pavonica alga, the current investigation could be assumed that P. pavonica alga adopted certain mechanism to minimize Cd stress damages.