Cold‐induced secondary dormancy and its regulatory mechanisms in <i>Beta vulgaris</i>

Hourston, James E.; Steinbrecher, Tina; Chandler, Jake O.; Pérez, Marta; Dietrich, Katrin; Turečková, Veronika; Tarkowská, Danuše; Strnad, Miroslav; Weltmeier, Fridtjof; Meinhard, Juliane; Fischer, Uwe; Fiedler‐Wiechers, Karin; Ignatz, Michael; Leubner‐Metzger, Gerhard

doi:10.1111/pce.14264

Cited by 11 publications

(12 citation statements)

References 98 publications

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“…In dormant black #1 seeds the ABA biosynthesis gene CalNCED3 was induced during imbibition suggesting a role in dormancy maintenance ( Figure 7A ). In agreement with this, for the B. vulgaris corresponding ABA metabolism gene upregulation in imbibed seeds during dormancy (NCEDs) and germination (CYP707As) has been reported ( Hermann et al., 2007 ; Hourston et al., 2022 ). In contrast to C. album seedlot #1, the morphs of seedlot #2 did not appreciably differ in their GA/ABA ratio patterns which increased 5-10 fold ( Figure 8B ).…”

Section: Discussionsupporting

confidence: 79%

“…Seeds were then snap frozen in liquid nitrogen and lyophilized for 2 days using a freeze dryer LYOVAC GT 2 (SEIB Industrie, Gothenburg, Sweden) and metabolites were extracted. The levels of GA and ABA pathway metabolites, physiologically active or non-active, were quantified by UHPLC-MS/MS as described previously ( Turečková et al., 2009 ; Urbanova et al., 2013 ; Walker et al., 2021 ; Hourston et al., 2022 ).…”

Section: Methodsmentioning

confidence: 99%

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Distinct hormonal and morphological control of dormancy and germination in Chenopodium album dimorphic seeds

et al. 2023

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Dormancy and heteromorphism are innate seed properties that control germination timing through adaptation to the prevailing environment. The degree of variation in dormancy depth within a seed population differs considerably depending on the genotype and maternal environment. Dormancy is therefore a key trait of annual weeds to time seedling emergence across seasons. Seed heteromorphism, the production of distinct seed morphs (in color, mass or other morphological characteristics) on the same individual plant, is considered to be a bet-hedging strategy in unpredictable environments. Heteromorphic species evolved independently in several plant families and the distinct seed morphs provide an additional degree of variation. Here we conducted a comparative morphological and molecular analysis of the dimorphic seeds (black and brown) of the Amaranthaceae weed Chenopodium album. Freshly harvested black and brown seeds differed in their dormancy and germination responses to ambient temperature. The black seed morph of seedlot #1 was dormant and 2/3rd of the seed population had non-deep physiological dormancy which was released by after-ripening (AR) or gibberellin (GA) treatment. The deeper dormancy of the remaining 1/3rd non-germinating seeds required in addition ethylene and nitrate for its release. The black seeds of seedlot #2 and the brown seed morphs of both seedlots were non-dormant with 2/3rd of the seeds germinating in the fresh mature state. The dimorphic seeds and seedlots differed in testa (outer seed coat) thickness in that thick testas of black seeds of seedlot #1 conferred coat-imposed dormancy. The dimorphic seeds and seedlots differed in their abscisic acid (ABA) and GA contents in the dry state and during imbibition in that GA biosynthesis was highest in brown seeds and ABA degradation was faster in seedlot #2. Chenopodium genes for GA and ABA metabolism were identified and their distinct transcript expression patterns were quantified in dry and imbibed C. album seeds. Phylogenetic analyses of the Amaranthaceae sequences revealed a high proportion of expanded gene families within the Chenopodium genus. The identified hormonal, molecular and morphological mechanisms and dormancy variation of the dimorphic seeds of C. album and other Amaranthaceae are compared and discussed as adaptations to variable and stressful environments.

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Section: Discussionsupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Distinct hormonal and morphological control of dormancy and germination in Chenopodium album dimorphic seeds

et al. 2023

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“…The likeliness of following hot, dry days would result in high levels of seedling mortality. Annual dormancy cycling of seed populations is known to be regulated by temperature alone or in combination with water potential 6,7,26–29 . Light is generally known to alleviate dormancy where darkness induces secondary dormancy in plants such as Arabidopsis 2,8,29–31 .…”

Section: Discussionmentioning

confidence: 99%

“…Secondary seed dormancy can be induced after shedding in non-dormant imbibed seeds by environmental stimuli like suboptimal temperature, hypoxia, or darkness [4][5][6][7][8][9] . Unless the secondary dormancy is released by antagonistic signals, seeds remain dormant even in conditions permissive for germination, indicating a memory effect as part of a dormancy cycle.…”

Section: Introductionmentioning

confidence: 99%

Long days induce adaptive secondary dormancy in seed of the Mediterranean plantAethionema arabicum

Mérai,

Graeber,

et al. 2024

Preprint

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Secondary dormancy is an adaptive trait that increases reproductive success by aligning seed germination with permissive conditions for seedling establishment.Aethionema arabicumis an annual plant and member of the Brassicaceae that grows in environments characterized by hot and dry summers.Aethionema arabicumseeds may germinate in early spring when seedling establishment is permissible. We demonstrate that long-day light regimes induce secondary dormancy in seed ofAethionema arabicum(CYP accession) repressing germination in summer when seedling establishment is riskier. Characterization of mutants screened for defective secondary dormancy demonstrated that RGL2 mediates repression of genes involved in GA signalling. Exposure to high temperature alleviates secondary dormancy, restoring germination potential. These data are consistent with the hypothesis that long-day-induced secondary dormancy and its alleviation by high temperatures, may be part of an adaptive response limiting germination to conditions permissive for seedling establishment in spring and autumn.

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“…While (genetic) research on the processes underlying primary dormancy is extensive, the molecular mechanisms controlling secondary seed dormancy are still poorly understood (Cadman et al, 2006; Finch-Savage and Leubner-Metzger, 2006; Holdsworth et al, 2008b; Footitt et al, 2013; Ibarra et al, 2016; Coughlan et al, 2017; Buijs, 2020; Laspina et al, 2020; Hourston et al, 2022). According to the hormonal balance model (Finkelstein et al, 2008), the ratio of abscisic acid (ABA) (promoting primary dormancy induction and dormancy maintenance) and gibberellic acid (GA) (promoting release of dormancy and germination) is the main determinant of the level of dormancy and seed germination (Finkelstein et al, 2008; Buijs et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

(Epi)genetic control of secondary seed dormancy depth and germination in Capsella bursa-pastoris

et al. 2022

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Despite the importance of secondary dormancy for plant life cycle timing and survival, there is insufficient knowledge about the (epigenetic) regulation of this trait at the molecular level. Our aim was to determine the role of (epi)genetic processes in the regulation of secondary seed dormancy using natural genotypes of the widely distributed Capsella bursa-pastoris. Seeds of nine ecotypes were exposed to control conditions or histone deacetylase inhibitors [trichostatin A (TSA), valproic acid] during imbibition to study the effects of hyper-acetylation on secondary seed dormancy induction and germination. Valproic acid increased secondary dormancy and both compounds caused a delay of t50 for germination (radicle emergence) but not of t50 for testa rupture, demonstrating that they reduced speed of germination. Transcriptome analysis of one accession exposed to valproic acid versus water showed mixed regulation of ABA, negative regulation of GAs, BRs and auxins, as well as up-regulation of SNL genes, which might explain the observed delay in germination and increase in secondary dormancy. In addition, two accessions differing in secondary dormancy depth (deep vs non-deep) were studied using RNA-seq to reveal the potential regulatory processes underlying this trait. Phytohormone synthesis or signalling was generally up-regulated for ABA (e.g. NCED6, NCED2, ABCG40, ABI3) and down-regulated for GAs (GA20ox1, GA20ox2, bHLH93), ethylene (ACO1, ERF4-LIKE, ERF105, ERF109-LIKE), BRs (BIA1, CYP708A2-LIKE, probable WRKY46, BAK1, BEN1, BES1, BRI1) and auxin (GH3.3, GH3.6, ABCB19, TGG4, AUX1, PIN6, WAT1). Epigenetic candidates for variation in secondary dormancy depth include SNL genes, histone deacetylases and associated genes (HDA14, HDA6-LIKE, HDA-LIKE, ING2, JMJ30), as well as sequences linked to histone acetyltransferases (bZIP11, ARID1A-LIKE), or to gene silencing through histone methylation (SUVH7, SUVH9, CLF). Together, these results show that phytohormones and epigenetic regulation play an important role in controlling differences in secondary dormancy depth between accessions.

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Cold‐induced secondary dormancy and its regulatory mechanisms in Beta vulgaris

Cited by 11 publications

References 98 publications

Distinct hormonal and morphological control of dormancy and germination in Chenopodium album dimorphic seeds

Distinct hormonal and morphological control of dormancy and germination in Chenopodium album dimorphic seeds

Long days induce adaptive secondary dormancy in seed of the Mediterranean plantAethionema arabicum

(Epi)genetic control of secondary seed dormancy depth and germination in Capsella bursa-pastoris

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