Trampling-induced ethylene production delays spikelet initiation in spring wheat

Abstract

Early sowing of spring wheat increases the risk of frost injury due to premature spikelet initiation under low temperatures. While trampling has been reported to delay spikelet initiation, its physiological mechanism remains unclear. We attempted to explain the delayed spikelet initiation caused by trampling in terms of the involvement of ethylene. The role of ethylene in trampling was investigated in the spring wheat cultivar Ayahikari by measuring ethylene production after trampling and applying the ethylene-releasing agent ethephon and the ethylene action inhibitor 1-methylcyclopropene (1-MCP). The effects of trampling and ethylene on the expression of VERNALIZATION1 (Vrn1) and FLOWERING LOCUS T (FT), key regulators of spikelet initiation, were also examined. Trampling significantly increased ethylene production and delayed young spike development. Exogenous application of ethephon mimicked the effect of trampling on young spike development, while 1-MCP reversed this effect. Furthermore, trampling suppressed the expression of Vrn1 and FT, similar to the effects observed in ethephon-treated plants. The present study indicated that ethylene mediated the effect of trampling on young spike development likely through the suppression of Vrn1 and FT expression, ultimately causing a delay in spikelet initiation. Our findings provide a mechanistic explanation and highlight trampling as a potential agronomic strategy for mitigating frost risk in early-sown spring wheat.

Keywords

Ethylene / Frost injury / Spring wheat / Trampling / Young spike development

Authors' contributions

Akina Mizumoto: Writing-original draft, Visualization, Investigation, Data curation, and Conceptualization; Daisuke Sasayama: Writing-review and editing, Validation, Supervision, and Methodology; Riona Osaki: Visualization, Investigation, and Data curation; Kota Nishimura: Investigation, and Data curation; and Tetsushi Azuma: Writing-review and editing, Supervision, Resources, and Project administration.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We thank Prof. K. Murai, Fukui Prefectural University, for valuable advice on the experimental methods. This work was supported by the Ministry of Agriculture, Forestry and Fisheries of Japan [Grant-in-Aid for Research (20602)].

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.crope.2025.05.001.

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