Zoospores of Chlamydomonas reinhardtii exhibit chemotaxis towards malt
ose, sucrose, xylose, mannitol, and ammonium. Ten independent mutants
defective in chemotaxis towards sugars have been isolated. These mutan
ts form five phenotypic classes. Genetic analysis of two mutant strain
s defective in chemotaxis to maltose (CHE1, CHE3) and two mutant strai
ns defective in chemotaxis to sucrose (CHE2, CHE4) indicated that the
defect in them depended on single nuclear recessive mutant alleles. Mu
tations mal1, mal2, suc1, and suc2 represent four chemotactic loci tha
t are unlinked to the marker mt located on the linkage group VI. Four
loci are unlinked to each other. These observations suggest that the m
al and the suc loci do not constitute a spatially single functional gr
oup.