From little things big things grow: karrikins and new directions in plant development

Waters, Mark T.

doi:10.1071/fp16405

Cited by 17 publications

(9 citation statements)

References 107 publications

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“…There is compelling evidence that at least two butenolide signaling pathways exist in vascular plants. The ancient KAI2 pathway has an as yet unknown butenolide ligand (KL; Conn and Nelson, 2016 ; Sun et al, 2016 ; Waters, 2017 ), which is neither SL nor karrikin. During the course of evolution, KAI2 underwent a gene duplication event which resulted in the D14 clade ( Delaux et al, 2012 ; Bennett and Leyser, 2014 ).…”

Section: Discussionmentioning

confidence: 99%

Comprehensive Analysis of DWARF14-LIKE2 (DLK2) Reveals Its Functional Divergence from Strigolactone-Related Paralogs

et al. 2017

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Strigolactones (SLs) and related butenolides, originally identified as active seed germination stimulants of parasitic weeds, play important roles in many aspects of plant development. Two members of the D14 α/β hydrolase protein family, DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are essential for SL/butenolide signaling. The third member of the family in Arabidopsis, DWARF 14-LIKE2 (DLK2) is structurally very similar to D14 and KAI2, but its function is unknown. We demonstrated that DLK2 does not bind nor hydrolyze natural (+)5-deoxystrigol [(+)5DS], and weakly hydrolyzes non-natural strigolactone (-)5DS. A detailed genetic analysis revealed that DLK2 does not affect SL responses and can regulate seedling photomorphogenesis. DLK2 is upregulated in the dark dependent upon KAI2 and PHYTOCHROME INTERACTING FACTORS (PIFs), indicating that DLK2 might function in light signaling pathways. In addition, unlike its paralog proteins, DLK2 is not subject to rac-GR24-induced degradation, suggesting that DLK2 acts independently of MORE AXILLARY GROWTH2 (MAX2); however, regulation of DLK2 transcription is mostly accomplished through MAX2. In conclusion, these data suggest that DLK2 represents a divergent member of the DWARF14 family.

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Section: Discussionmentioning

confidence: 99%

Comprehensive Analysis of DWARF14-LIKE2 (DLK2) Reveals Its Functional Divergence from Strigolactone-Related Paralogs

et al. 2017

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“…SLs have received increasing attention in recent years, particularly with respect to molecular signalling mechanisms (Bennett and Leyser, ; Waters et al ., ). At the same time, investigations into the karrikin response pathway have shown that signalling pathways of both types of butenolide compound share many molecular features in common (Waters, ). Thus, studies into karrikins have informed our understanding of SLs, and vice versa.…”

Section: Introductionmentioning

confidence: 99%

“…F‐box proteins confer a substrate‐specific polyubiquitination process upon target proteins, labelling them for proteolytic destruction via the 26S proteasome (Xu et al ., ). In Arabidopsis, AtD14 and KAI2 provide specificity to ligand perception via MAX2, and max2 mutants show the combined phenotype of kai2 Atd14 double mutants (Waters et al ., ; Bennett et al ., ; Waters, ). There is ample evidence that D14 and MAX2 (or their orthologues) interact physically in an SL‐dependent manner as part of the SL signalling mechanism (Hamiaux et al ., ; Jiang et al ., ; Zhou et al ., ; Zhao et al ., ).…”

Section: Introductionmentioning

confidence: 99%

An allelic series at the KARRIKIN INSENSITIVE 2 locus of Arabidopsis thaliana decouples ligand hydrolysis and receptor degradation from downstream signalling

et al. 2018

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Karrikins are butenolide compounds present in post-fire environments that can stimulate seed germination in many species, including Arabidopsis thaliana. Plants also produce endogenous butenolide compounds that serve as hormones, namely strigolactones (SLs). The receptor for karrikins (KARRIKIN INSENSITIVE 2; KAI2) and the receptor for SLs (DWARF14; D14) are homologous proteins that share many similarities. The mode of action of D14 as a dual enzyme receptor protein is well established, but the nature of KAI2-dependent signalling and its function as a receptor are not fully understood. To expand our knowledge of how KAI2 operates, we screened ethyl methanesulphonate (EMS)-mutagenized populations of A. thaliana for mutants with kai2-like phenotypes and isolated 13 new kai2 alleles. Among these alleles, kai2-10 encoded a D184N protein variant that was stable in planta. Differential scanning fluorimetry assays indicated that the KAI2 D184N protein could interact normally with bioactive ligands. We developed a KAI2-active version of the fluorescent strigolactone analogue Yoshimulactone Green to show that KAI2 D184N exhibits normal rates of ligand hydrolysis. KAI2 D184N degraded in response to treatment with exogenous ligands, suggesting that receptor degradation is a consequence of ligand binding and hydrolysis, but is insufficient for signalling activity. Remarkably, KAI2 D184N degradation was hypersensitive to karrikins, but showed a normal response to strigolactone analogues, implying that these butenolides may interact differently with KAI2. These results demonstrate that the enzymatic and signalling functions of KAI2 can be decoupled, and provide important insights into the mechanistic events that underpin butenolide signalling in plants.

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“…karrikins and glyceronitrile) that are responsible for the stimulation of germination (6,9). Researchers have found that karrikinolide (KAR1) is the most abundant and active karrikin in smoke and that enhances germination and seedling growth in many plants even at very low concentrations (7,8,(10)(11)(12). Goren-Saglam et al Karrikinolide Promotes Seed Germination Leaf senescence is an important developmental stage affected by various internal and external factors, such as leaf age, hormone levels, exposure to darkness, and environmental stresses (13,14).…”

Section: Introductionmentioning

confidence: 99%

Karrikinolide Promotes Seed Germination but Has no Effect on Leaf Segment Senescence in Triticum aestivum L.

Sağlam¹,

Duygun²,

Kaya³

et al. 2019

Eur J Biol

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Objective: Germination and senescence are the two most important developmental processes in the plant life cycle. While seed germination is an important physiological event for the continuity of species, leaf senescence is also an important developmental process that impacts crop yields. Karrikins are a group of plant growth regulators found in the smoke generated by burning plant material. It has been suggested that karrikinolide (KAR1) is generally the most active karrikin in terms of stimulating germination. Materials and Methods: In this study, the effect of karrikinolide on germination and leaf segment senescence in wheat was investigated. For this purpose, control, 1 nM, 0.01, 0.1, 1, and 10 μM KAR1 solutions were used. Firstly, the wheat seeds were germinated in the dark in these solutions and germination percentages and root lengths were measured. Secondly, 4 of first leaf segments (3cm. each) from 10-day-old wheat seedlings were placed in petri dishes containing 1, 10, 100 μM KAR1 and distilled water as a control. Following incubation, fresh weight, chlorophyll content, cell death amounts and total protein amounts were determined. Results: The obtained data shows that 1 μM KAR1 promotes germination and root length to the greatest extent. This suggests that karrikins have a promoting effect on the germination of wheat seeds. Our results demonstrate that KAR1 has no effect on leaf segment senescence. Conclusion: Our study suggests that KAR1 has the potential to be used in agriculture to improve germination and seedling growth of crop species.

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From little things big things grow: karrikins and new directions in plant development

Cited by 17 publications

References 107 publications

Comprehensive Analysis of DWARF14-LIKE2 (DLK2) Reveals Its Functional Divergence from Strigolactone-Related Paralogs

Comprehensive Analysis of DWARF14-LIKE2 (DLK2) Reveals Its Functional Divergence from Strigolactone-Related Paralogs

An allelic series at the KARRIKIN INSENSITIVE 2 locus of Arabidopsis thaliana decouples ligand hydrolysis and receptor degradation from downstream signalling

Karrikinolide Promotes Seed Germination but Has no Effect on Leaf Segment Senescence in Triticum aestivum L.

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