Phloem-Expressed CLAVATA3/ESR-like Genes in Potato

In potato, phloem tissues transport sugars and signal molecules to the tuber for growth and storage. The CLAVATA3/ESR-like (CLE) family of plant peptides plays an important role in regulating plant development. In this study, we identified a set of phloem-expressed CLE genes in Solanum tuberosum L. (StCLEs). We analyzed the phloem transcriptome of potato and found that 10 out of 41 StCLE genes were expressed in phloem cells, with StCLE12 and StCLE19 showing the highest expression levels. StCLE12 has an identical CLE domain to the Arabidopsis TDIF peptides, which are known to play a crucial role in maintaining the vascular meristem. StCLE19 has the highest sequence similarity to the Arabidopsis CLE25 peptide, which is involved in the formation of the phloem element and signaling in response to dehydration stress. The overexpression of StCLE12 and another potato TDIF-like gene, StCLE8, promoted vascular cell proliferation and delayed leaf senescence. On the other hand, plants with overexpression of StCLE19 were unable to form adventitious roots and demonstrated the absence of ordered cambium cell layers in the vascular bundles.