Deregulation of a Ca2+/calmodulin-dependent kinase leads to spontaneous nodule development

Leïla Tirichine, Haruko Imaizumi-Anraku, Satoko Yoshida, Yasuhiro Murakami, Lene H. Madsen, Hiroki Miwa, Tomomi Nakagawa, Niels Sandal, Anita S. Albrektsen, Masayoshi Kawaguchi, Allan Downie, Shusei Sato, Satoshi Tabata, Hiroshi Kouchi, Martin Parniske, Shinji Kawasaki, Jens Stougaard

Research output: Contribution to journalArticlepeer-review

333 Citations (Scopus)


Induced development of a new plant organ in response to rhizobia is the most prominent manifestation of legume root-nodule symbiosis with nitrogen-fixing bacteria. Here we show that the complex root-nodule organogenic programme can be genetically deregulated to trigger de novo nodule formation in the absence of rhizobia or exogenous rhizobial signals. In an ethylmethane sulphonate-induced snf1 (spontaneous nodule formation) mutant of Lotus japonicus, a single amino-acid replacement in a Ca2+/calmodulin- dependent protein kinase (CCaMK) is sufficient to turn fully differentiated root cortical cells into meristematic founder cells of root nodule primordia. These spontaneous nodules are genuine nodules with an ontogeny similar to that of rhizobial-induced root nodules, corroborating previous physiological studies. Using two receptor-deficient genetic backgrounds we provide evidence for a developmentally integrated spontaneous nodulation process that is independent of lipochitin-oligosaccharide signal perception and oscillations in Ca 2+ second messenger levels. Our results reveal a key regulatory position of CCaMK upstream of all components required for cell-cycle activation, and a phenotypically divergent series of mutant alleles demonstrates positive and negative regulation of the process.

Original languageEnglish
Pages (from-to)1153-1156
Number of pages4
Issue number7097
Publication statusPublished - 2006 Jun 29
Externally publishedYes

ASJC Scopus subject areas

  • General


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