The pea photoperiod response gene STERILE NODES is an ortholog of LUX ARRHYTHMO1[W][OPEN]

The <em>STERILE NODES</em> (<em>SN</em>) locus in pea (<em>Pisum sativum</em>) was one of the first photoperiod response genes to be described and provided early evidence for the genetic control of long-distance signaling in flowering-time regulation. Lines homozygous for recessive <em>sn</em> mutations are early flowering and photoperiod insensitive, with an increased ability to promote flowering across a graft union in short-day conditions. Here, we show that <em>SN</em> controls developmental regulation of genes in the <em>FT</em> family and rhythmic regulation of genes related to circadian clock function. Using a positional and functional candidate approach, we identify <em>SN</em> as the pea ortholog of <em>LUX ARRHYTHMO</em>, a GARP transcription factor from Arabidopsis (<em>Arabidopsis thaliana</em>) with an important role in circadian clock function. In addition to induced mutants, sequence analysis demonstrates the presence of at least three other independent, naturally occurring loss-of-function mutations among known <em>sn</em> cultivars. Examination of genetic and regulatory interactions between <em>SN</em> and two other circadian clock genes, <em>HIGH RESPONSE TO PHOTOPERIOD</em> (<em>HR</em>) and <em>DIE NEUTRALIS</em> (<em>DNE</em>), suggests a complex relationship in which <em>HR</em> regulates expression of <em>SN</em> and the role of <em>DNE</em> and <em>HR</em> in control of flowering is dependent on <em>SN</em>. These results extend previous work to show that pea orthologs of all three Arabidopsis evening complex genes regulate clock function and photoperiod-responsive flowering and suggest that the function of these genes may be widely conserved.