Oligogalacturonides inhibit growth and induce changes in S6K phosphorylation in maize ( Zea mays L. var. Chalqueño)

Cell growth is regulated by the target of rapamycin (TOR) signaling pathway, which integrates environmental cues in eukaryotes. In plants the final organ size is determined by the number and cell size. Several proteins involved in the TOR signaling pathway are conserved in plants, although a differential regulation has been proposed because insensitivity to rapamycin by Arabidopsis thaliana was reported. Reports about the role of auxin in the activation of maize S6 ribosomal protein kinase (S6K), a downstream substrate of TOR, have been published indicating a central role of the TOR pathway in the regulation of plant growth. However, in addition to phytohormones, there are a variety of plant growth regulators, including cell wall fragments called oligogalacturonides (OGs). Here we report the effect of OGs on maize growth and development, as well as on S6K activation. We found that oligogalacturonides inhibit coleoptile growth and modify root architecture of maize seedlings. Western blot analyses indicated a modulation of maize S6K activity from seedlings and embryonic axes in response to OGs treatment. These results show that oligosaccharides regulate growth and development through the modulation of TOR signaling pathway in maize.