Smoke and Hormone Mirrors: Action and Evolution of Karrikin and Strigolactone Signaling

Morffy, Nicholas; Faure, Lionel; Nelson, David C.

doi:10.1016/j.tig.2016.01.002

Cited by 91 publications

(79 citation statements)

References 85 publications

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“…As well as the similarities in chemical structures between KARs and SL, many components of these two signaling pathways are analogs or homologs ( Figure 1 ) (Flematti et al, 2015; Morffy et al, 2016). Firstly, both signaling pathways are composed of receptors, E3 ligases and signal repressors; secondly, the receptor of SL signal, AtD14, is a homolog of KAI2 which is the receptor of KARs (Kagiyama et al, 2013; Waters et al, 2013); thirdly, the repressor of SL signaling pathway, D53, is also a homolog of SMAX1, the repressor in KARs signaling transduction pathway (Jiang et al, 2013; Zhou F. et al, 2013).…”

Section: The Relationship Between Kars and Slmentioning

confidence: 99%

Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

et al. 2017

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Seed germination and early seedling establishment are critical stages during a plant’s life cycle. These stages are precisely regulated by multiple internal factors, including phytohormones and environmental cues such as light. As a family of small molecules discovered in wildfire smoke, karrikins (KARs) play a key role in various biological processes, including seed dormancy release, germination regulation, and seedling establishment. KARs show a high similarity with strigolactone (SL) in both chemical structure and signaling transduction pathways. Current evidence shows that KARs may regulate seed germination by mediating the biosynthesis and/or signaling transduction of abscisic acid (ABA), gibberellin (GA) and auxin [indoleacetic acid (IAA)]. Interestingly, KARs regulate seed germination differently in different species. Furthermore, the promotion effect on seedling establishment implies that KARs have a great potential application in alleviating shade avoidance response, which attracts more and more attention in plant molecular biology. In these processes, KARs may have complicated interactions with phytohormones, especially with IAA. In this updated review, we summarize the current understanding of the relationship between KARs and SL in the chemical structure, signaling pathway and the regulation of plant growth and development. Further, the crosstalk between KARs and phytohormones in regulating seed germination and seedling development and that between KARs and IAA during shade responses are discussed. Finally, future challenges and research directions for the KAR research field are suggested.

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Section: The Relationship Between Kars and Slmentioning

confidence: 99%

Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

et al. 2017

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“…In 2008, it was shown that SLs also function as internally mobile signals that regulate branching [2,3], and they are now recognized as hormones with diverse roles in plant growth regulation (reviewed in [4]). Since then significant progress has been made toward understanding how SLs are produced, transported, and perceived (reviewed in [4][5][6]). Here we highlight some of the most recent findings in SL biology and discuss their implications for parasitic weed control.…”

Section: Introductionmentioning

confidence: 99%

“…The current SL signaling model is analogous to other phytohormone signaling mechanisms, in particular those of gibberellin, auxin, and jasmonate, which feature hormone-activated degradation of proteins that repress downstream growth responses (reviewed in [5]). Both SL and KAR signaling through D14 and KAI2 require the F-box protein MORE AXILLARY GROWTH 2 (MAX2)/DWARF3 (D3)/RAMOSUS4 (RMS4) [2,3,47].…”

Section: Introductionmentioning

confidence: 99%

“…SMXL are divided into four clades that were present before the divergence of dicots and monocots. To date, growth control by SMAX1 and SMXL2 (red) is associated with KAI2 signaling and KAR responses, whereas growth control by the D53 and SMXL6,7,8 clade (blue) is associated with D14 signaling and SL responses (reviewed in [5]). SMXL4/AtHSPR (green) has been implicated in stress responses [67].…”

Section: Introductionmentioning

confidence: 99%

“…A popular hypothesis is that SMXL regulates gene expression via interactions with the TOP-LESS (TPL) family of transcriptional co-repressors, similar to AUX/IAA and JAZ proteins in auxin and jasmonate signaling, respectively (reviewed in [5]). SMXL proteins have a highly conserved EAR motif that is necessary for TPL interactions [50,51 ,52 ], but the significance of this motif for SMXL function in vivo has not been evaluated.…”

Section: Introductionmentioning

confidence: 99%

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Strigolactones, super hormones in the fight against Striga

Khosla

Nelson

2016

Current Opinion in Plant Biology

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Strigolactones are plant hormones that control diverse aspects of plant growth, but are also exuded into soil as recruitment signals for arbuscular mycorrhizal fungi interactions. Highly damaging parasitic weeds in the Orobanchaceae family have coopted strigolactones as germination cues that indicate the presence of a host. Recent studies have established how strigolactones are actively transported within and out of plants. Key components of the strigolactone signaling system have been identified, including strigolactone receptors in angiosperms and parasites, as well as downstream targets that are polyubiquitinated and proteolyzed following strigolactone perception. The basis for protein-protein interactions among these signaling components has also been explored. We propose several strategies to translate current knowledge of strigolactone transport and signaling into parasite control methods.

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Karrikins: Germination Stimulants Produced by Wildfires

Smith¹

2019

Encyclopedia of Life Sciences

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Karrikins are simple organic chemicals produced by wildfires that stimulate germination of dormant seeds in the soil. They are present in the smoke and char produced by the fire and are washed into the soil by the following rains. Many plant species have evolved such that their seeds remain dormant in the soil until they encounter karrikins, whereupon they can germinate. This strategy has the advantage that emerging seedlings will have plenty of light and a supply of nutrients released by the fire. Such plants are termed ‘fire ephemerals’ because they appear after fires, then flower, produce seed and die. It is believed that karrikins mimic an unidentified endogenous germination hormone. Karrikins are also similar to endogenous hormones called strigolactones that control plant development. Karrikin perception by seeds apparently requires a protein closely related to the strigolactone receptor. Karrikins or smoke can be used to stimulate germination in horticulture and landscape revegetation. Key Concepts Wildfires stimulate seeds in the soil to germinate which contributes to rapid revegetation. Seeds from many plant species are adapted to respond to chemicals produced by fire. The most active germination stimulant produced by wildfires is a butenolide named ‘karrikin’. Karrikins can influence germination and also seedling development. The receptor protein and molecular components of the response pathway have been identified. Karrikins mimic an ancient endogenous plant hormone that has not yet been identified. Karrikins stimulate germination of agricultural weeds and so might be useful for their control. Karrikins provide tools and knowledge to help us manage our natural landscapes. Karrikins might be useful in seed conservation work and in seed banks. The karrikin signalling system might be applied in crop breeding for environmental resilience.

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Smoke and Hormone Mirrors: Action and Evolution of Karrikin and Strigolactone Signaling

Cited by 91 publications

References 85 publications

Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

Strigolactones, super hormones in the fight against Striga

Karrikins: Germination Stimulants Produced by Wildfires

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