CLAVATA3/ESR-related 2 peptides regulate root sucrose level and root/shoot ratio in Arabidopsis (Plant Physiol)

Roots are dependent on shoot-produced sucrose for energy associated with growth and nutrient uptake. The CLAVATA3/ESR2-related peptides (CLEs) regulate several aspects of plant growth. Okamoto et al. present evidence on the involvement of CLEs in conveying the root sucrose demand to the shoot.  Carbon starvation upregulates CLE2 and CLE3 and increases the translocation of CLE2 from root to shoot. Transient ectopic expression of CLE2 and overexpression of CLE2 in vascular tissues increases the root sucrose content. The septuple cle mutant, Atcle1-7, is deficient in root sucrose status. Under diurnally fluctuating as well as normal light conditions, shoot/root mass was significantly higher in Atcle1-7 septuple mutants in comparison to wild type. The expression of the sucrose/H⁺ transporter SUC2 (involved in sucrose phloem loading) was lower in Atcle1-7 septuple mutants. Application of synthetic CLE2 peptide could rescue root sucrose content of Atcle1-7 mutants and partially rescue SUC2 expression. Reciprocal grafting of Atcle1-7 with wild type roots and shoots revealed that root genotype of CLE could regulate shoot SUC2 gene expression. Thus, CLEs are root-derived signals that pass information to shoots and determine root sucrose content.  (Summary by Lekshmy Sathee @lekshmysnair) Plant Physiol. 10.1093/plphys/kiac227