Analysis of peptide PSY1 responding transcripts in the two Arabidopsis plant lines: wild type and psy1r receptor...

Small-secreted peptides are emerging as important components in cell-cell communication during basic developmental stages of plant cell growth and development. Plant peptide containing sulfated tyrosine 1 (PSY1) has been reported to promote cell expansion and differentiation in the elongation zone of roots. PSY1 action is dependent on a receptor PSY1R that triggers a signaling cascade leading to cell elongation. However little is known about cellular functions and the components involved in PSY1-based signaling cascade.

Differentially expressed genes were identified in a wild type plant line and in a psy1r receptor mutant line of Arabidopsis thaliana after treatment with PSY1. Seventy-seven genes were found to be responsive to the PSY1 peptide in wild type plants while 154 genes were responsive in the receptor mutant plants. PSY1 activates the transcripts of genes involved in cell wall modification. Gene enrichment analysis revealed that PSY1-responsive genes are involved in responses to stimuli, metabolic processes and biosynthetic processes. The significant enrichment terms of PSY1-responsive genes were higher in psy1r mutant plants compared to in wild type plants. Two parallel responses to PSY1 were identified, differing in their dependency on the PSY1R receptor. Promoter analysis of the differentially expressed genes identified a light regulatory motif in some of these.

PSY1-responsive genes are involved in cellular functions and stimuli responses suggesting a crosstalk between developmental cues and environmental stimuli. Possibly, two parallel responses to PSY1 exist. A motif involved in light regulation was identified in the promoter region of the differentially expressed genes. Reduced hypocotyl growth was observed in etiolated receptor mutant seedlings.