Genetic variation among
seven strains of Dunaliella salina (Chlorophyta) with industrial
potential, based on RAPD banding patterns and on nuclear ITS rDNA sequences
P.I. Gómez, M.A. González-2004
Aquaculture, 233(1-4): 149-162
Abstract:
Dunaliella salina (Chlorophyta) is a halophilic microalga
cultivated as a natural source of β-carotene in several countries,
including Chile. Previous studies of some Chilean strains of this microalga
have shown a great variability in their physiological and genetic
attributes. Random amplified polymorphic DNA (RAPD) band patterns and
nuclear ribosomal DNA internal transcribed spacer (ITS-1 and ITS-2)
sequences were used to genotypically characterize three Chilean and four
foreign (from Mexico, China, Australia and Israel) strains of D. salina
with industrial potential. Unweighted pair group mean average (UPGMA)
cluster analysis of RAPD data distinguished, at 70% similarity, two
clusters. One cluster included all of the foreign strains, except the one
from Australia, and the other grouped two of the Chilean strains (CONC-001
and CONC-007). The other Chilean strain (CONC-006) and the Australian strain
appeared as single entities. Neighbor-joining (NJ), maximum parsimony (MP)
and maximum likelihood (ML) analyses of the ITS sequence data yielded four
clades, most of them well supported: there were two clades containing
exclusively one strain, CONC-006 from Chile (86–94% support) and the one
from Australia (98–100% support); the third clade grouped the strains from
Mexico, China and Israel (99–100% support), and, the fourth clade, the
strains CONC-001 and CONC-007 from Chile (100% support). Both RAPD banding
pattern and ITS sequence data were consistent in resolving the same genetic
relatedness among the strains analyzed. For both approaches, the strain
CONC-006 from Chile and the strain from Australia were the most divergent
entities within the group. Furthermore, the strain CONC-006 appeared
genetically more related to the foreign strains than to the other Chilean
ones. The physiological attributes exhibited by these strains of D.
salina are mostly in agreement with the genetic relationships deduced
from this study.