A CLE–SUNN module regulates strigolactone content and symbiosis (Nature Plants)

The symbiosis between plants and arbuscular mycorrhizal fungi is conditional. Plants that are limited for phosphate release strigolactones into the soil, promoting changes in the fungi that facilitate the symbiosis. Müller et al. found that a Medicago gene encoding a CLE peptide, MtCLE53, is induced upon root colonization. When this gene is ectopically overexpressed, plants resist colonization, and genes involved in strigolactone biosynthesis are downregulated. A gene encoding a receptor-like kinase, SUNN, was also upreagulated in MtCLE53-overexpressing plants. In sunn mutant plants, strigolactone biosynthesis is not downregulated in respones to MtCLE53-overexpression. Thus, a negative-feedback loop for symbiosis involving CLE53-SUNN and strigolactones has been identified. (Summary by Mary Williams) Nature Plants 10.1038/s41477-019-0501-1