ISSR-PCR-Based Genetic Diversity Analysis on Copper-Tolerant Versus Wild Type Strains of the Unicellular Alga Chlorella vulgaris

(Abdullah Mousa Al-Zahrani)

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Abstract

The unicellular alga Chlorella vulgaris was isolated from Al-Asfar Lake, Al-Ahsa province of Saudi Arabia. Two different isolates were subcultured under laboratory conditions. The wild type was grown under a regular concentration of copper, whereas the other isolate was grown under a progressively increasing copper concentration. An Inter Simple Sequence Repeats (ISSR) analysis was performed using DNA isolated from the wild type and tolerant strains. The sum of the scored bands of the wild type was 155, with 100 (64.5%) considered to be polymorphic bands, whereas the resistant strain displayed 147 bands, with 92 (62.6%) considered to be polymorphic bands. The sum of the scored bands of a mixed sample was 117 bands, of which only 4 (3.4%) were considered to be polymorphic. The average Neis genetic diversity (h) and Shannon-Weiner diversity indices (I) were 0.3891 and 0.5394, respectively. These results clearly indicate that the adaptation to a high level of copper in Chlorella vulgaris is not merely physiological but rather driven by modifications at the genomic level. Key Words: Chlorella vulgaris, copper tolerance, genetic diversity, Green Algae, ISSR-PCR.
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