A peptide encoding gene MdCLE8 regulates lateral root development in apple

Nitrogen is not only an essential nutrient for plant, but also an important signal molecule to integrate and regulate gene expression, metabolism and growth. Plant peptides are considered as a new type of hormone, and play an important regulatory role in plant growth and development. However, little is known about the co-regulation network between nitrogen and peptide hormones in plant. Here we identified an apple MdCLE8 gene, which encodes a putative peptide, induced by nitrogen deficiency in apple. Ectopic expression of MdCLE8 inhibited lateral root formation in Arabidopsis under nitrogen deficiency. Similarly, overexpression of MdCLE8 inhibited lateral root development in apple adventitious roots, and this inhibition was amplified under nitrogen deficiency treatment. Further studies showed that MdCLE8 may inhibit the expression of several key genes during lateral root emergence stage in Arabidopsis, thereby inhibiting the emergence of lateral root from root cortex cells. Collectively, our study not only broadened the gene regulatory network under the influence of nitrogen in apple, but also expanded the function of CLE peptide hormones in apple. Key message The apple peptide encoding gene MdCLE8 is induced by nitrogen deficiency signaling and negatively regulates lateral root formation in plants.