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Species-specific thermal thresholds for postdispersal embryo growth in Apiaceae.

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Title: Species-specific thermal thresholds for postdispersal embryo growth in Apiaceae.
Authors: Nadi S; Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran, Tehran, Iran., Maleki K; Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, USA., Soltani E; Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran, Tehran, Iran., Javid MG; Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran, Tehran, Iran., Vandelook F; Meise Botanic Garden, Meise, Belgium.
Source: American journal of botany [Am J Bot] 2026 Jul; Vol. 113 (7), pp. e70231. Date of Electronic Publication: 2026 Jun 30.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Wiley Country of Publication: United States NLM ID: 0370467 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1537-2197 (Electronic) Linking ISSN: 00029122 NLM ISO Abbreviation: Am J Bot Subsets: MEDLINE
Imprint Name(s): Publication: <2018-> : [Philadelphia, PA] : Wiley
Original Publication: Baltimore Md : Botanical Society Of America
MeSH Terms: Seeds*/growth & development , Seeds*/embryology , Seeds*/physiology , Temperature*, Gibberellins/pharmacology ; Species Specificity ; Germination ; Phylogeny ; Plant Dormancy
Abstract: Premise: Temperature is a primary regulator of seed development. In seeds with morphological (MD) or morphophysiological (MPD) dormancy, embryo elongation represents a distinct postdispersal developmental phase that precedes germination. However, the thermal thresholds governing this embryo growth phase remain poorly quantified. We quantified species-specific embryo-growth thermal niches to provide a mechanistic framework for understanding regeneration timing and its evolutionary constraints.
Methods: We estimated cardinal temperatures-base (Tb), optimum (To), and maximum (Tm)-for embryo growth in 10 Apiaceae species, a family in which MD and MPD are very common due to the presence of underdeveloped embryos. Seeds were incubated at five temperatures (5-25°C) with and without gibberellic acid (GA3). Embryo growth rates were modeled using nonlinear thermal performance curves within a multimodel inference framework, followed by phylogenetic signal analyses.
Results: Substantial interspecific variation was found, with Tb ranging from 0 to 6.5°C, To from 5 to 25°C, and Tm from 21.5 to 31°C. GA3 generally increased growth rates and widened thermal ranges by reducing Tb and raising Tm, though responses were strongly species-specific. Phylogenetic analyses revealed significant signal for all thermal thresholds (Tb, To, Tm), indicating that evolutionary history constrains these thermal niches for postdispersal embryo growth.
Conclusions: Postdispersal embryo growth constitutes a distinct, quantifiable thermal niche rather than a mere proxy for germination. By explicitly treating postdispersal embryo growth as a distinct thermal niche rather than a proxy for germination, this study extends thermal threshold theory to an overlooked developmental phase and provides a mechanistic framework for understanding dormancy release and regeneration timing under variable climatic conditions.
(© 2026 Botanical Society of America.)
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Grant Information: FWO V510523N) FWO grant
Contributed Indexing: Keywords: cardinal temperatures; embryo growth; gibberellic acid (GA3); morphophysiological dormancy; seeds; temperature
Substance Nomenclature: 0 (Gibberellins)
BU0A7MWB6L (gibberellic acid)
Entry Date(s): Date Created: 20260701 Date Completed: 20260729 Latest Revision: 20260730
Update Code: 20260730
PubMed Central ID: PMC13408554
DOI: 10.1002/ajb2.70231
PMID: 42381347
Database: MEDLINE
Description
ISSN:1537-2197
DOI:10.1002/ajb2.70231