Assessing the use of mitochondrial cox1 gene and cox2-3 spacer for genetic diversity study of Malaysian Gracilaria changii (Gracilariaceae, Rhodophyta) from Peninsular Malaysia

Advances in DNA-based genetic markers provide the essential tools in measurement of genetic diversity relating to the evolution, biogeography, and systematics of red algae by exploiting genetic variation in the entire genome of organisms. The understanding of genetic diversity in Gracilaria changii (Gracilariaceae, Rhodophyta) will provide valuable information for conservation, plant breeding management, and strain selection for cultivation. However, information of intraspecific genetic variation is still rudimentary. In this study, two mitochondrial encoded markers, cytochrome oxidase subunit 1 (cox1) and intergenic spacer between the cytochrome oxidase subunits 2 and 3 (cox2-3 spacer) were used to investigate genetic diversity in 40 individuals of G. changii collected from 11 different geographically distinct populations from Peninsular Malaysia. Seven distinct mitochondrial haplotypes were identified with the cox1 gene and three mitochondrial haplotypes with the cox2-3 spacer. Intraspecific nucleotide differences ranged from 0 to 6 bp for the cox1 and 0-4 bp for the cox2-3 spacer, respectively. This is the first report comparing the suitability of mitochondrial markers of the cox1 gene and the cox2-3 spacer for genetic diversity studies on G. changii. The present study showed that the cox1 gene is a potential molecular marker to infer intraspecific genetic variation in red macroalgae. The cox1 marker is more variable compared to the cox2-3 spacer and revealed genetic variation and phylogeographic structure for this ecologically and economically important species.