PLANT PHYSIOLOGY , Vol 112, Issue 1 99-104, Copyright © 1996 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Salt-Sensitive Mutants of Chlamydomonas reinhardtii Isolated after Insertional Tagging
R. Prieto, J. M. Pardo, X. Niu, R. A. Bressan and P. M. Hasegawa
Center for Plant Environmental Stress Physiology, 1165 Horticulture Building, Purdue University, West Lafayette, Indiana 47907-1165
We describe the isolation of salt-sensitive Chlamydomonas reinhardtii
mutants by insertional mutagenesis using the nitrate reductase (Nit1) gene.
The plasmid pMN24, containing Nit1, was used for transformation of 305CW15
(nit1 cw15 mt+), and transformants were selected for complementation of the
nit- phenotype. From 6875 nit+ colonies, four transformants (S4, S18, S46,
and S66) were isolated that exhibited both Na+ and Li+ sensitivity (sod-),
and another transformant (S33) was selected that exhibited sensitivity to
Li+ but not Na+ (lit-) based on relative growth comparisons with the
wild-type strain. S33, S46, and S66 were no more growth inhibited by
sorbitol than was 305CW15. In comparison, S4 and S18 exhibited substantial
growth inhibition in medium supplemented with sorbitol. Genetic analyses
indicated that the salt-sensitive mutants were each defective in a single
recessive gene. The mutant genes in S4 (sod1), S33 (lit1), and S66 (sod3)
are linked to a functional copy of Nit1 and are presumably tagged with a
pMN24 insertion.