miPEP858/miR858-MYB3-PSK4 module regulates growth and development in Arabidopsis

Small molecules, peptides and miRNAs, are the crucial regulators of plant growth. Here, we show the importance of cross-talk between miPEP858a/miR858a and Phytosulfokine (PSK4) in regulating plant growth and development in Arabidopsis. Genome-wide expression analysis suggested modulated expression of PSK4 in miR858 mutant and overexpression, miR858OX, plants. The silencing of PSK4 in miR858OX plants compromised the growth, whereas over-expression of PSK4 in miR858 mutant rescued the developmental defects. The exogenous application of synthetic PSK4 further complemented the plant development in mutant plants. Exogenous treatment of synthetic miPEP858a in PSK4 mutant led to clathrin-mediated internalization of the peptide however did not enhance growth as in the case of wild-type plants. We also demonstrate that the MYB3 is an important molecular component participating in miPEP858a/miR858a-PSK4 module. Finally, our work highlights the signalling between miR858/miPEP858-MYB3-PSK4 in modulating the expression of key elements involved in auxin responses leading to the regulation of growth. One-sentence summarySignaling network between small molecules, miPEP858a/miR858a and phytosulfokine, regulates plant growth in Arabidopsis.