The small ubiquitin-like modifier (SUMO) modification alters the subcellular distribution and function of its substrates. Here we show the major role of SUMO during the development of the
Caenorhabditis elegansreproductive system. smo-1deletion mutants develop into sterile adults with abnormal somatic gonad, germ line, and vulva. SMO-1::GFP reporter is highly expressed in the somatic reproductive system. smo-1animals lack a vulval-uterine connection as a result of impaired ventral uterine π-cell differentiation and anchor cell fusion. Mutations in the LIN-11 LIM domain transcription factor lead to a uterine phenotype that resembles the smo-1phenotype. LIN-11 is sumoylated, and its sumoylation is required for its activity during uterine morphogenesis. Expression of a SUMO-modified LIN-11 in the smo-1background partially rescued π-cell differentiation and retained LIN-11 in nuclear bodies. Thus, our results identify the reproductive system as the major SUMO target during postembryonic development and highlight LIN-11 as a physiological substrate whose sumoylation is associated with the formation of a functional vulval-uterine connection.