| Summary: | Legume plants form nitrogen-fixing nodules in symbiosis with soil bacteria rhizobia. The number of symbiotic nodules is controlled at the whole-plant level with autoregulation of nodulation (AON), which includes a shoot-acting CLV1-like receptor kinase and mobile CLE (CLAVATA3/ENDOSPERM SURROUNDING REGION-related) peptides that are produced in the root in response to rhizobia inoculation. In addition to rhizobia-induced CLE peptides, nitrate-induced <i>CLE</i> genes have been identified in <i>Lotus japonicus</i> and <i>Glycine max</i>, which inhibited nodulation when overexpressed. However, nitrate-induced <i>CLE</i> genes that systemically suppress nodulation in AON-dependent manner have not been identified in <i>Medicago truncatula</i>. Here, we found that <i>MtCLE35</i> expression is activated by both rhizobia inoculation and nitrate treatment in <i>M. truncatula</i>, similarly to <i>L. japonicus CLE</i> genes. Moreover, we found that MtCLE35 systemically suppresses nodulation in AON-dependent manner, suggesting that MtCLE35 may mediate nitrate-induced inhibition of nodulation in <i>M. truncatula</i>.
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