Ethylene represses the promoting influence of cytokinin on cell division and expansion of cotyledons in etiolated Arabidopsis thaliana seedlings

PeerJ. 2022 Oct 31:10:e14315. doi: 10.7717/peerj.14315. eCollection 2022.

Abstract

The plant hormones ethylene and cytokinin influence many processes; sometimes they act cooperatively, other times antagonistically. To study their antagonistic interaction, we used the cotyledons of etiolated, intact seedlings of Arabidopsis thaliana. We focused on cell division and expansion, because both processes are quantified readily in paradermal sections. Here, we show that exogenous cytokinins modestly stimulate cell division and expansion in the cotyledon, with a phenyl-urea class compound exerting a larger effect than benzyl-adenine. Similarly, both processes were stimulated modestly when ethylene response was inhibited, either chemically with silver nitrate or genetically with the eti5 ethylene-insensitive mutant. However, combining cytokinin treatment with ethylene insensitivity was synergistic, strongly stimulating both cell division and expansion. Evidently, ethylene represses the growth promoting influence of cytokinin, whether endogenous or applied. We suggest that the intact etiolated cotyledon offers a useful system to characterize how ethylene antagonizes cytokinin responsiveness.

Keywords: Cell clusters; Cell division; Cell enlargement; Cotyledon plate meristem; Cytokinin; Ethylene-cytokinin antagonism; Ethylene-insensitive mutant; Hormone crosstalk.

MeSH terms

  • Arabidopsis* / genetics
  • Cell Division
  • Cotyledon
  • Cytokinins* / pharmacology
  • Ethylenes / pharmacology
  • Seedlings / genetics

Substances

  • Cytokinins
  • ethylene
  • Ethylenes

Grants and funding

The authors received no funding for this work.