<i>ShHTL7</i> requires functional brassinosteroid signaling to initiate GA-independent germination

Bunsick, Michael; Lumba, Shelley

doi:10.1080/15592324.2020.1855845

Cited by 4 publications

(3 citation statements)

References 19 publications

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“…Brassinosteroid, ET, GA and JA enhanced germination as follows: (i) BS genes BS1, BSK BZR and BAK1 were induced in germinating seeds pointing to a positive regulatory of seed germination through BSs. It is known that BIN2 interact with ABI5 to mediate antagonism between ABA and BS (Hu and Yu, 2014) and that SL-dependent Striga germination requires functional BS signaling (Bunsick and Lumba, 2020). (ii) Ethylene proteins (ETR, ERF and EIN2) were consistently induced in germinating seeds reinforcing the extensively studied antagonism of ethylene on ABA reviewed in (Linkies and Leubner-Metzger, 2012; Gazzarrini and Tsai, 2015).…”

Section: Resultsmentioning

confidence: 99%

A transcriptome atlas ofStriga hermonthicagermination

Irafasha

Mutinda

Mobegi³

et al. 2022

Preprint

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Societal Impact StatementWitchweeds, parasitic plants of the genusStriga, are nicknamed “cereal killers” because of their devasting destruction of Africa’s most staple cereals, including maize, sorghum, millets, and upland rice. The parasite relies on biomolecules emitted from the host roots to germinate and therefore initiate its infectious lifecycle. Some sorghum varieties have evolved to not produce effective germination stimulants, making them resistant to the parasite. Here, we assess genetic factors that underpinStrigagermination. We discuss how such knowledge can be used to develop newStrigamanagement strategies through the disruption of host-parasite communication exchange.SummarySeeds of the parasitic plantStrigaare dormant. They only germinate in response to biomolecules emitted from the host’s root exudate, strigolactones (SL). But, it is now emerging thatStrigagermination is a much more complex process regulated by crosstalk of hormone signaling pathways.To further understand the genetic basis of the communication exchange betweenStrigaand its host sorghum, we performed a comparative transcriptomic analysis. We sought to identify major transcriptomic changes that define the germination process inStrigaand a set of genes that may contribute to the differences in germination rates.Results showed that germination proceeds immediately after SL perception and is marked by a wave of transcriptional reprogramming to allow for metabolic processes of energy mobilization. Cluster analysis using self-organizing maps (SOMs) revealed a time-phased and genotype-differentiated response to germination stimulation. The variation in germination was also a function of hormonal crosstalk. The early germination stage was associated with significant repression of genes in the abscisic acid (ABA) biosynthesis pathway. Other hormones influenced germination as follows: (i) ABA and auxin repressed germination, (ii) brassinosteroid, ethylene and jasmonic acid promoted germination, and (iii) cytokinin had a more prominent role post-germination rather than during germination. Perception of SL sets the germination programme leading to different rates of germination in sorghum followed by a complex hormonal regulation network that acts to either repress or enhance germination. These results have far-reaching implications for developingStrigamanagement strategies by disrupting hormonal communication exchange.

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Section: Resultsmentioning

confidence: 99%

A transcriptome atlas ofStriga hermonthicagermination

Irafasha

Mutinda

Mobegi³

et al. 2022

Preprint

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“…There is also evidence that, when GA biosynthesis is inhibited, the ability of KAR–KL signalling to trigger germination is dependent on a functional BR signalling pathway. This is potentially due to the antagonistic interaction of BR signalling on ABA signalling; loss of BR signalling may cause stronger ABA-imposed seed dormancy that over-rides germination promotion by KAR–KL ( Bunsick and Lumba, 2021 ).…”

Section: Kar–kl Signalling In Plant Developmentmentioning

confidence: 99%

Karrikin signalling: impacts on plant development and abiotic stress tolerance

Kamran,

Melville,

Waters

2023

Journal of Experimental Botany

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Plants rely upon a diverse range of metabolites to control growth and development, and to overcome stress that results from suboptimal conditions. Karrikins (KARs) are a class of butenolide compounds found in smoke that stimulate seed germination and regulate various developmental processes in plants. KARs are perceived via a plant α/β-hydrolase called KARRIKIN INSENSITIVE2 (KAI2), which also functions as a receptor for a postulated phytohormone, provisionally termed KAI2 ligand (KL). Considered natural analogues of KL, KARs have been extensively studied for their effects on plant growth and their crosstalk with plant hormones. The perception and response pathway for KAR–KL signalling is closely related to that of strigolactones, another class of butenolides with numerous functions in regulating plant growth. KAR–KL signalling influences seed germination, seedling photomorphogenesis, root system architecture, abiotic stress responses, and arbuscular mycorrhizal symbiosis. Here, we summarize current knowledge of KAR–KL signalling, focusing on its role in plant development, its effects on stress tolerance, and its interaction with other signalling mechanisms.

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“…Events further downstream that link SMAX1/SMXL2 degradation to specific developmental outputs are gradually emerging and complex. For brevity, we will only note here that KAR/KL signalling integrates with light, temperature, auxin, ethylene, abscisic acid, brassinosteroid and gibberellin pathways (Nelson et al ., 2009, 2010; Waters & Smith, 2013; Wei et al ., 2016; Brun et al ., 2019; Bunsick et al ., 2020, 2022; Carbonnel et al ., 2020a; Bunsick & Lumba, 2021; Bursch et al ., 2021; Hamon‐Josse et al ., 2022; Kim et al ., 2022; Park et al ., 2022; Villaécija‐Aguilar et al ., 2022). This will be a rich area for future study.…”

Section: The Functions Of Smxl Protein Domainsmentioning

confidence: 99%

Karrikin perception and signalling

Waters

Nelson

2022

New Phytologist

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Summary Karrikins (KARs) are a class of butenolide compounds found in smoke that were first identified as seed germination stimulants for fire‐following species. Early studies of KARs classified the germination and postgermination responses of many plant species and investigated crosstalk with plant hormones that regulate germination. The discovery that Arabidopsis thaliana responds to KARs laid the foundation for identifying mutants with altered KAR responses. Genetic analysis of KAR signalling revealed an unexpected link to strigolactones (SLs), a class of carotenoid‐derived plant hormones. Substantial progress has since been made towards understanding how KARs are perceived and regulate plant growth, in no small part due to advances in understanding SL perception. KAR and SL signalling systems are evolutionarily related and retain a high degree of similarity. There is strong evidence that KARs are natural analogues of an endogenous signal(s), KAI2 ligand (KL), which remains unknown. KAR/KL signalling regulates many developmental processes in plants including germination, seedling photomorphogenesis, and root and root hair growth. KAR/KL signalling also affects abiotic stress responses and arbuscular mycorrhizal symbiosis. Here, we summarise the current knowledge of KAR/KL signalling and discuss current controversies and unanswered questions in this field.

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ShHTL7 requires functional brassinosteroid signaling to initiate GA-independent germination

Cited by 4 publications

References 19 publications

A transcriptome atlas ofStriga hermonthicagermination

A transcriptome atlas ofStriga hermonthicagermination

Karrikin signalling: impacts on plant development and abiotic stress tolerance

Karrikin perception and signalling

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