SMAX1-dependent seed germination bypasses GA signalling in Arabidopsis and Striga

Bunsick, Michael; Toh, Shigeo; Wong, Cynthia; Xu, Zhenhua; Ly, George; McErlean, Christopher S. P.; Pescetto, Gianni; Nemrish, Kawther Elfituri; Sung, Priscilla; Li, Jack Daiyang; Scholes, J. D.; Lumba, Shelley

doi:10.1038/s41477-020-0653-z

Cited by 51 publications

(33 citation statements)

References 47 publications

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“…When ShHTL receptors from Striga were expressed in Arabidopsis, the seeds could germinate without the requirement of GA in a MAX2-and SMAX1-dependent manner (Bunsick et al, 2020). These results support that coevolution of receptor-target pairs was involved in the establishment of distinct signaling pathways for SL and karrikin, which have been selected in adaptive evolution of land plants (Waters et al, 2017).…”

Section: Discussionmentioning

confidence: 61%

Karrikin Signaling Acts Parallel to and Additively with Strigolactone Signaling to Regulate Rice Mesocotyl Elongation in Darkness

et al. 2020

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Seedling emergence in monocots depends mainly on mesocotyl elongation, requiring the coordination between developmental signals and environmental stimuli. Strigolactones (SLs) and karrikins are butenolide compounds that regulate various developmental processes; both are able to negatively regulate rice (Oryza sativa) mesocotyl elongation in the dark. Here, we report that a karrikin signaling complex, DWARF 14-LIKE (D14L)-DWARF 3 (D3)-Oryza sativa SUPPRESSOR OF MAX2 1 (OsSMAX1) mediates the regulation of rice mesocotyl elongation in the dark. We demonstrate that D14L recognizes the karrikin signal and recruits

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Section: Discussionmentioning

confidence: 61%

Karrikin Signaling Acts Parallel to and Additively with Strigolactone Signaling to Regulate Rice Mesocotyl Elongation in Darkness

et al. 2020

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“…The KL pathway appears to play a prominent role in the seed development of vascular plants (Toh et al ., 2012; Conn et al ., 2015; Tsuchiya et al ., 2015; Bunsick et al ., 2020). Temperature, light, and soil moisture are common cues that affect germination in autotrophic plants, and this typically results from altered ratios of the plant hormones abscisic acid (ABA) and gibberellic acid (GA) (Toh et al ., 2008; Toh et al ., 2012).…”

Section: Strigolactones As a Developmental Regulatormentioning

confidence: 99%

“…Interestingly, after exposure to high temperatures Arabidopsis seeds (Col‐0 accession) germinate less well, but this thermoinhibition is rescued by rac‐GR24 treatment in the wild type (WT), but not in max2 plants (Toh et al ., 2012). This evidence suggests that a latent KL‐ and/or SL‐mediated germination signalling pathway functions in some annual plants under non‐optimal conditions (Toh et al ., 2012; Bunsick et al ., 2020).…”

Section: Strigolactones As a Developmental Regulatormentioning

confidence: 99%

“…In summary, SLs play important developmental roles across the land plant phylogeny (Gomez‐Roldan et al ., 2008; Nelson et al ., 2011; Proust et al ., 2011; Toh et al ., 2012; Villaécija‐Aguilar et al ., 2019; Bunsick et al ., 2020). Although SL and KAR/KL have distinct control over certain developmental decisions, the extent to which the D14 and KAI2 signalling pathways can be separated with regards to other developmental decisions (e.g., lateral root outgrowth) is not completely clear (Villaécija‐Aguilar et al ., 2019).…”

Section: Strigolactones As a Developmental Regulatormentioning

confidence: 99%

“…In Arabidopsis, the presence of GA induces the degradation of DELLA repressors to trigger germination, but GA does not germinate Striga seeds (Toh et al ., 2012). Unlike GA‐deficient Arabidopsis mutants, which are unable to germinate, a recent study demonstrated that GA‐depleted Striga seeds can germinate on SLs (Bunsick et al ., 2020). To recapitulate this finding in a genetic system, Bunsick et al .…”

Section: Strigolactones and Parasitic Plant Germinationmentioning

confidence: 99%

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On the outside looking in: roles of endogenous and exogenous strigolactones

2020

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Summary A collection of small molecules called strigolactones (SLs) act as both endogenous hormones to control plant development and as ecological communication cues between organisms. SL signalling overlaps with that of a class of smoke‐derived compounds, karrikins (KARs), which have distinct yet overlapping developmental effects on plants. Although the roles of SLs in shoot and root development, in the promotion of arbuscular mycorrhizal (AM) fungal branching and in parasitic plant germination have been well characterized, recent data have illustrated broader roles for these compounds in the rhizosphere. Here, we review the known roles of SLs in development, growth of AM fungi and germination of parasitic plants to develop a framework for understanding the use of SLs as molecules of communication in the rhizosphere. It appears, for example, that there are many connections between SLs and phosphate utilization. Low phosphate levels regulate SL metabolism and, in turn, SLs sculpt root and shoot architecture to coordinate growth and optimize phosphate uptake from the environment. Plant‐exuded SLs attract fungal symbionts to deliver inorganic phosphate (Pi) to the host. These and other examples suggest the boundary between exogenous and endogenous SL functions can be easily blurred and a more holistic view of these small molecules is likely to be required to fully understand SL biology. Related to this, we summarize and discuss evidence for a primitive role of SLs in moss as a quorum sensing‐like molecule, providing a unifying concept of SLs as endogenous and exogenous signalling molecules.

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Rapid analysis of strigolactone receptor activity in a Nicotiana benthamiana dwarf14 mutant

et al. 2022

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DWARF14 (D14) is an ɑ/β‐hydrolase and receptor for the plant hormone strigolactone (SL) in angiosperms. Upon SL perception, D14 works with MORE AXILLARY GROWTH2 (MAX2) to trigger polyubiquitination and degradation of DWARF53(D53)‐type proteins in the SUPPRESSOR OF MAX2 1‐LIKE (SMXL) family. We used CRISPR‐Cas9 to generate knockout alleles of the two homoeologous D14 genes in the Nicotiana benthamiana genome. The Nbd14a,b double mutant had several phenotypes that are consistent with the loss of SL perception in other plants, including increased axillary bud outgrowth, reduced height, shortened petioles, and smaller leaves. A ratiometric fluorescent reporter system was used to monitor degradation of SMXL7 from Arabidopsis thaliana (AtSMXL7) after transient expression in N. benthamiana and treatment with the strigolactone analog GR24. AtSMXL7 was degraded after treatment with GR245DS, which has the stereochemical configuration of natural SLs, as well as its enantiomer GR24ent‐5DS. In Nbd14a,b leaves, AtSMXL7 abundance was unaffected by rac‐GR24 or either GR24 stereoisomer. Transient coexpression of AtD14 with the AtSMXL7 reporter in Nbd14a,b restored the degradation response to rac‐GR24, but required an active catalytic triad. We used this platform to evaluate the ability of several AtD14 mutants that had not been characterized in plants to target AtSMXL7 for degradation.

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SMAX1-dependent seed germination bypasses GA signalling in Arabidopsis and Striga

Cited by 51 publications

References 47 publications

Karrikin Signaling Acts Parallel to and Additively with Strigolactone Signaling to Regulate Rice Mesocotyl Elongation in Darkness

Karrikin Signaling Acts Parallel to and Additively with Strigolactone Signaling to Regulate Rice Mesocotyl Elongation in Darkness

On the outside looking in: roles of endogenous and exogenous strigolactones

Rapid analysis of strigolactone receptor activity in a Nicotiana benthamiana dwarf14 mutant

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