Abstract
Caenorhabditis elegans
responds to its complex chemical environment using a small number of chemosensory neurons. Each of these neurons exhibits a unique sensory response repertoire. The developmental mechanisms that generate this diversity of function are largely unknown. Many
C. elegans
chemosensory neurons, including the AWA and ASG neurons, arise as lineal sisters of an asymmetric division. Here we describe the gene
unc-130
, which plays a role in the generation of the AWA and ASG neurons. In
unc-130
mutants, the ASG neurons adopt the fate of the AWA neurons.
unc-130
encodes a member of the forkhead domain family of transcription factors, and is expressed in the precursors to AWA and ASG neurons. Misexpression of
unc-130
in the AWA neurons is partly sufficient to repress the AWA fate, but not to promote ASG fate.
unc-130
also plays a role in the development of additional chemosensory neurons. Our experiments show that the ASG neurons share a developmental default state in common with three types of olfactory neurons. We propose that distinct cell fates and hence diversity of function in the chemosensory neurons of
C. elegans
are generated in a hierarchical manner, utilizing both lineage-dependent and independent mechanisms.