The LIN-29 transcription factor is required for proper morphogenesis of the Caenorhabditis elegans male tail.

The Caenorhabditis elegans gene lin-29 encodes a zinc-finger transcription factor that is required for hypodermal cell terminal differentiation and proper vulva morphogenesis. Here we demonstrate that lin-29 is also required in males for productive mating. We show that lin-29 males can perform the early mating behaviors including response to hermaphrodite contact and vulva location, but they do not perform the subsequent steps of vulva attachment via spicule insertion and sperm transfer. Consistent with this observation, we found that lin-29 mutant spicules are on average 43% shorter than wild-type spicules while other male mating structures appear unaltered. In lin-29 mutants, spicule development goes awry after the generation of spicule cells, when spicule morphogenesis occurs in wild-type males. We show that LIN-29 accumulates in many cells of the wild-type male tail, including those that form the spicules. We demonstrate, through analysis of genetic mosaics, that the formation of wild-type-length spicules requires lin-29(+) in the AB.p lineage, the lineage that gives rise to the spicules and other male copulatory structures. Our mosaic analysis also reveals a role for lin-29(+) in the P1 lineage, which mainly produces sex muscles, cells of the somatic gonad, and body wall muscles.