Short Peptides Dramatically Regulate Key Growth Genes in Tobacco Plants

Plant development is a highly intricate process, precisely orchestrated by various internal and external factors, including peptide signaling molecules. Specific gene families, such as CLE (CLAVATA3/ESR-related), KNOX1 (KNOTTED1-like homeobox), and GRF (GROWTH-REGULATING FACTOR), are known to play fundamental roles in meristem maintenance, organ development, and overall plant architecture. Despite their known importance, the precise mechanisms by which short exogenous peptides modulate the expression of these critical regulatory genes in model organisms like Nicotiana tabacum have remained largely uncharacterized.

The study revealed profound and statistically significant alterations in the expression of key developmental genes in response to peptide treatments. Treatment with tetrapeptide A consistently led to a 2.3-fold upregulation of CLE1 expression (p<0.01) compared to untreated control plants, suggesting a direct influence on stem cell maintenance pathways. Conversely, KNOX1 expression, critical for meristem development, was notably downregulated by 45% (p<0.05) in plants treated with hexapeptide B, potentially impacting leaf morphology. The combined application of tetrapeptide A and hexapeptide B resulted in a 1.8-fold synergistic increase in CLE3 expression, indicating complex regulatory interactions. Control plants exhibited no significant changes in the expression of any of these gene families throughout the experimental period. The most striking finding was that tetrapeptide A robustly induced a 3.1-fold increase in GRF5 expression (p<0.001) specifically at the 48-hour time point, highlighting its potent regulatory role in pathways governing cell proliferation and overall plant growth.