Identification and Functional Analysis of the CLAVATA3/embryo Surrounding Region-Related ( CLE ) Gene Family in Tartary Buckwheat Suggests the Promoting Effect of FtCLE7 on Growth and Nitrogen Accumulation

Abstract Low nitrogen use efficiency caused by irrational nitrogen fertilization restricts Tartary buckwheat (TB) yield improvement. CLE peptides are key signaling molecules regulating plant nitrogen response, yet their functions in TB remain unclear. Herein, 16 FtCLE genes were identified in TB, and all encoding proteins contained conserved bioactive CLE mature peptides. The root-specific and high nitrogen-induced gene, FtCLE7, was screened as the key CLE member by expression analysis. Exogenous synthetic FtCLE7 peptide treatment significantly promoted growth and nitrogen accumulation in TB, and reshaped rhizosphere microbial communities. Transcriptome analysis demonstrated that FtCLE7 peptide changed the expression of genes involved in hormone signaling, phenylpropanoid biosynthesis, transcription regulation, and receptor-like kinases. Additionally, overexpression of FtCLE7 in tobacco verified its positive regulatory role in growth and nitrogen accumulation. This study clarifies the biological function of FtCLE7 in modulating nitrogen accumulation, providing a theoretical basis for breeding nitrogen-efficient TB varieties and developing novel peptide fertilizers.