Plant hormone signaling: Is upside down right side up?

Bunsick, Michael; McCullough, Rachel; McCourt, Peter; Lumba, Shelley

doi:10.1016/j.pbi.2021.102070

Cited by 16 publications

(8 citation statements)

References 45 publications

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“…We suggest when looking at fundamental processes such as germination it is more informative to reference pathways by their bottom effectors like SMAX1. 38…”

Section: Resultsmentioning

confidence: 99%

HTL/KAI2 signalling substitutes for light to control plant germination

Bunsick

Pescetto

et al. 2022

Preprint

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Deciphering signalling pathways is essential to understanding how organisms respond to environmental cues but elucidating how these signalling pathways evolve in new environments is less clear.1,2 Most plants, for example, monitor multiple environmental cues to optimize the time and place to germinate. Some root parasitic plants, however, germinate in response to small molecules like strigolactones (SLs) emanating from host roots3,4 whilst a number of ephemeral weeds germinate in response to chemicals called karrikins (KARs) released after a forest fire.5,6 Although these species represent distinct clades, they use the same HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE 2 (HTL/KAI2) signalling pathway to perceive strigolactones or karrikins, which suggests convergent evolution.3,5 Because specialist lifestyles are derived traits, it is not clear if HTL/KAI2 signalling in these species evolved from a specific germination-signalling pathway or whether this pathway had other functions that were co-opted for specialist germination circumstances. Here, we show HTL/KAI2 signalling in Arabidopsis bypasses the light requirement for germination. In part, this is because the HTL/KAI2 downstream component, SMAX1 impinges on PHYTOCHROME INTERACTING FACTOR 1/PHYTOCHROME INTERACTING FACTOR 3-LIKE 5 (PIF1/PIL5)-regulated hormone response pathways conducive to germination. We identified Arabidopsis accessions that can germinate in the dark, which had altered expression of HTL/KAI2 signalling components, suggesting that divergence in this signalling pathway occurs in nature. Moreover, Arabidopsis HTL/KAI2-regulated gene signatures were observed in germinating Striga seed. The ability of HTL/KAI2 signalling to substitute for light advances an explanation for how some specialist plants evolved their underground germination behaviour in response to specific environments.

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“…We suggest when looking at fundamental processes such as germination it is more informative to reference pathways by their bottom effectors like SMAX1. 38…”

Section: Resultsmentioning

confidence: 99%

HTL/KAI2 signalling substitutes for light to control plant germination

Bunsick

Pescetto

et al. 2022

Preprint

Self Cite

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“…Phytohormones are key regulators of multiple developmental processes ( Bunsick et al, 2021 ) and take part of many signalling networks that control stress responses ( Ku et al, 2018 ). Because phytohormones are natural and non-toxic compounds, it was suggested that their application as chemical control agents could be safe and environmentally friendly ( Wang et al, 2020 ).…”

Section: Survey Methodologymentioning

confidence: 99%

Stress-regulated elements in Lotus spp., as a possible starting point to understand signalling networks and stress adaptation in legumes

Menéndez

Ruíz

2021

PeerJ

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Although legumes are of primary economic importance for human and livestock consumption, the information regarding signalling networks during plant stress response in this group is very scarce. Lotus japonicus is a major experimental model within the Leguminosae family, whereas L. corniculatus and L. tenuis are frequent components of natural and agricultural ecosystems worldwide. These species display differences in their perception and response to diverse stresses, even at the genotype level, whereby they have been used in many studies aimed at achieving a better understanding of the plant stress-response mechanisms. However, we are far from the identification of key components of their stress-response signalling network, a previous step for implementing transgenic and editing tools to develop legume stress-resilient genotypes, with higher crop yield and quality. In this review we scope a body of literature, highlighting what is currently known on the stress-regulated signalling elements so far reported in Lotus spp. Our work includes a comprehensive review of transcription factors chaperones, redox signals and proteins of unknown function. In addition, we revised strigolactones and genes regulating phytochelatins and hormone metabolism, due to their involvement as intermediates in several physiological signalling networks. This work was intended for a broad readership in the fields of physiology, metabolism, plant nutrition, genetics and signal transduction. Our results suggest that Lotus species provide a valuable information platform for the study of specific protein-protein (PPI) interactions, as a starting point to unravel signalling networks underlying plant acclimatation to bacterial and abiotic stressors in legumes. Furthermore, some Lotus species may be a source of genes whose regulation improves stress tolerance and growth when introduced ectopically in other plant species.

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“…This conceptual view of phytohormones as conditional modulators of gene expression has implications for understanding the stepwise assembly of hormone-response pathways during evolution ( Bowman et al 2017 ; Mutte et al 2018 ; Blázquez et al 2020 ). Increasing evidence indicates that protein components of various phytohormone signaling cascades predated the recruitment of the hormone into the pathway and thus have the capacity to control output responses independently of the hormone ( Mutte et al 2018 ; Sun et al 2019 ; Bunsick et al 2021 ). For example, auxin appears to have been recruited as a signal based on its ability to promote protein–protein interactions between preexisting components of the pathway, thereby enabling efficient control of TF activity ( Mutte et al 2018 ; Cao et al 2022 ).…”

Section: Phytohormones As Regulatory Metabolitesmentioning

confidence: 99%

Phytohormones in a universe of regulatory metabolites: lessons from jasmonate

Gasperini,

Howe

2024

Plant Physiology

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Small-molecule phytohormones exert control over plant growth, development, and stress responses by coordinating the patterns of gene expression within and between cells. Increasing evidence indicates that currently recognized plant hormones are part of a larger group of regulatory metabolites that have acquired signaling properties during the evolution of land plants. This rich assortment of chemical signals reflects the tremendous diversity of plant secondary metabolism, which offers evolutionary solutions to the daunting challenges of sessility and other unique aspects of plant biology. A major gap in our current understanding of plant regulatory metabolites is the lack of insight into the direct targets of these compounds. Here, we illustrate the blurred distinction between classical phytohormones and other bioactive metabolites by highlighting the major scientific advances that transformed the view of jasmonate from an interesting floral scent to a potent transcriptional regulator. Lessons from jasmonate research generally apply to other phytohormones and thus may help provide a broad understanding of regulatory metabolite-protein interactions. In providing a framework that links small-molecule diversity to transcriptional plasticity, we hope to stimulate future research to explore the evolution, functions, and mechanisms of perception of a broad range of plant regulatory metabolites.

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Plant hormone signaling: Is upside down right side up?

Cited by 16 publications

References 45 publications

HTL/KAI2 signalling substitutes for light to control plant germination

HTL/KAI2 signalling substitutes for light to control plant germination

Stress-regulated elements in Lotus spp., as a possible starting point to understand signalling networks and stress adaptation in legumes

Phytohormones in a universe of regulatory metabolites: lessons from jasmonate

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