Plant Physiol, May 2002, Vol. 129, pp. 7-12
Stable Chloroplast Transformation of the Unicellular Red Alga
Porphyridium Species1
Miri
Lapidot,
Dina
Raveh,
Alex
Sivan,
Shoshana (Malis)
Arad, and
Michal
Shapira*
Department of Life Sciences (M.L., D.R., M.S.) and Institute of
Applied Biosciences (A.S., S.M.A.), Ben Gurion University of the
Negev, Beer-Sheva 84105, Israel
Red algae are extremely attractive for biotechnology because
they synthesize accessory photosynthetic pigments (phycobilins and
carotenoids), unsaturated fatty acids, and unique cell wall sulfated
polysaccharides. We report a high-efficiency chloroplast transformation system for the unicellular red microalga
Porphyridium sp. This is the first genetic
transformation system for Rhodophytes and is based on use of a mutant
form of the gene encoding acetohydroxyacid synthase [AHAS(W492S)] as
a dominant selectable marker. AHAS is the target enzyme of the
herbicide sulfometuron methyl, which effectively inhibits growth of
bacteria, fungi, plants, and algae. Biolistic transformation of
synchronized Porphyridium sp. cells with the mutant
AHAS(W492S) gene that confers herbicide resistance gave a high
frequency of sulfomethuron methyl-resistant colonies. The mutant AHAS
gene integrated into the chloroplast genome by homologous
recombination. This system paves the way for expression of foreign
genes in red algae and has important biotechnological implications.
1
This work was supported by the Center for
Polysaccharide Research at the Ben-Gurion University of the Negev.
*
Corresponding author; e-mail shapiram{at}bgumail.bgu.ac.il; fax
972-8-647-2992.
© 2002 American Society of Plant Physiologists
