Location: Chemistry ResearchTitle: Cytokinin promotes jasmonic acid accumulation in the control of maize leaf growth
|UYEHARA, AIMEE - University Of Hawaii|
|DEL VALLE-ECHEVARRIA, ANGEL - University Of Hawaii|
|NELISSEN, HILDE - Ghent University|
|DEMUYNCK, KIRIN - Ghent University|
|CAHILL, JAMES - Iowa State University|
|JANDER, GEORG - Cornell University|
|MUSZYNSKI, MICHAEL - University Of Hawaii|
Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2023
Publication Date: 8/21/2023
Citation: Uyehara, A.N., Del Valle-Echevarria, A.R., Hunter Iii, C.T., Nelissen, H., Demuynck, K., Cahill, J.F., Gorman, Z.J., Jander, G., Muszynski, M.G. 2023. Cytokinin promotes jasmonic acid accumulation in the control of maize leaf growth. Plants. 12:16. https://doi.org/10.3390/plants12163014.
Interpretive Summary: Plant hormone interactions govern responses to internal and external stimuli. The balance between plant growth and defense is an important decision point for plants to determine where to commit limited resources. Cytokinin, known for its role in stimulating cell division, is an important regulator of plant shape and size. Here we examine the Hairy Sheath Frayed1 (Hsf1) maize mutant, which perceives an overabundance of cytokinin and also accumulates jasmonic acid (JA) to abnormally high levels. In collaboration with the University of Hawai'i at Manoa, ARS scientists at the Center for Medical, Agricultural, and Veterinary Entomology in Gainesville, FL show that cytokinin hypersignalling promotes JA production by turning on genes for JA biosynthesis. These results highlight a heretofore unknown interplay between cytokinin and JA and reveal a possible new mechanism for the plant growth-defense trade-off. A greater understanding of such mechanisms, especially regarding the hormones and genetic pathways underlying their regulation, may facilitate the development of crops with greater resiliency against pathogens and insects while maintaining high yields.
Technical Abstract: Growth of plant organs results from the combined activity of cell division and cell expansion. The coordination of these two processes depends on the interplay between multiple hormones that determine final organ size. Using the semidominant Hairy Sheath Frayed1 (Hsf1) maize mutant, that hypersignals the perception of cytokinin (CK), we show that CK can reduce leaf size and growth rate by decreasing cell division. Linked to CK hypersignaling, the Hsf1 mutant has increased jasmonic acid (JA) content, a hormone that can inhibit cell division. Treatment of wild type seedlings with exogenous JA reduces maize leaf size and growth rate, while JA deficient maize mutants have increased leaf size and growth rate. Expression analysis revealed increased transcript accumulation of several JA pathway genes in the Hsf1 leaf growth zone. A transient treatment of growing wild type maize shoots with exogenous CK also induced JA pathway gene expression, although this effect was blocked by co-treatment with cycloheximide. Together our results suggest that CK can promote JA accumulation possibly through increased expression of specific JA pathway genes.