Kamran M

References (4)

Title : Karrikin signalling: impacts on plant development and abiotic stress tolerance - Kamran_2023_J.Exp.Bot__
Author(s) : Kamran M , Melville KT , Waters MT
Ref : J Exp Bot , : , 2023
Abstract : 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 alpha/beta-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 summarise the current knowledge of KAR-KL signalling, focussing on its role in plant development, its effects on stress tolerance, and its interaction with other signalling mechanisms.
ESTHER : Kamran_2023_J.Exp.Bot__
PubMedSearch : Kamran_2023_J.Exp.Bot__
PubMedID: 38001035

Title : Perception of butenolides by Bacillus subtilis via the alpha\/beta hydrolase RsbQ - Melville_2023_Curr.Biol__
Author(s) : Melville KT , Kamran M , Yao J , Costa M , Holland M , Taylor NL , Fritz G , Flematti GR , Waters MT
Ref : Current Biology , : , 2023
Abstract : The regulation of behavioral and developmental decisions by small molecules is common to all domains of life. In plants, strigolactones and karrikins are butenolide growth regulators that influence several aspects of plant growth and development, as well as interactions with symbiotic fungi.(1)(,)(2)(,)(3) DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are homologous enzyme-receptors that perceive strigolactones and karrikins, respectively, and that require hydrolase activity to effect signal transduction.(4)(,)(5)(,)(6)(,)(7) RsbQ, a homolog of D14 and KAI2 from the gram-positive bacterium Bacillus subtilis, regulates growth responses to nutritional stress via the alternative transcription factor SigmaB (sigma(B)).(8)(,)(9) However, the molecular function of RsbQ is unknown. Here, we show that RsbQ perceives butenolide compounds that are bioactive in plants. RsbQ is thermally destabilized by the synthetic strigolactone GR24 and its desmethyl butenolide equivalent dGR24. We show that, like D14 and KAI2, RsbQ is a functional butenolide hydrolase that undergoes covalent modification of the catalytic histidine residue. Exogenous application of both GR24 and dGR24 inhibited the endogenous signaling function of RsbQ in vivo, with dGR24 being 10-fold more potent. Application of dGR24 to B. subtilis phenocopied loss-of-function rsbQ mutations and led to a significant downregulation of sigma(B)-regulated transcripts. We also discovered that exogenous butenolides promoted the transition from planktonic to biofilm growth. Our results suggest that butenolides may serve as inter-kingdom signaling compounds between plants and bacteria to help shape rhizosphere communities.
ESTHER : Melville_2023_Curr.Biol__
PubMedSearch : Melville_2023_Curr.Biol__
PubMedID: 38183985
Gene_locus related to this paper: bacsu-RsbQ

Title : KARRIKIN UP-REGULATED F-BOX 1 (KUF1) imposes negative feedback regulation of karrikin and KAI2 ligand metabolism in Arabidopsis thaliana - Sepulveda_2022_Proc.Natl.Acad.Sci.U.S.A_119_e2112820119
Author(s) : Sepulveda C , Guzman MA , Li Q , Villaecija-Aguilar JA , Martinez SE , Kamran M , Khosla A , Liu W , Gendron JM , Gutjahr C , Waters MT , Nelson DC
Ref : Proc Natl Acad Sci U S A , 119 :e2112820119 , 2022
Abstract : Significance: Karrikins are chemicals in smoke that stimulate regrowth of many plants after fire. However, karrikin responses are not limited to species from fire-prone environments and can affect growth after germination. Putatively, this is because karrikins mimic an unknown signal in plants, KAI2 ligand (KL). Karrikins likely require modification in plants to become bioactive. We identify a gene, KUF1, that appears to negatively regulate biosynthesis of KL and metabolism of a specific karrikin. KUF1 expression increases in response to karrikin or KL signaling, thus forming a negative feedback loop that limits further activation of the signaling pathway. This discovery will advance understanding of how karrikins are perceived and how smoke-activated germination evolved. It will also aid identification of the elusive KL.
ESTHER : Sepulveda_2022_Proc.Natl.Acad.Sci.U.S.A_119_e2112820119
PubMedSearch : Sepulveda_2022_Proc.Natl.Acad.Sci.U.S.A_119_e2112820119
PubMedID: 35254909

Title : KARRIKIN INSENSITIVE2 regulates leaf development, root system architecture and arbuscular-mycorrhizal symbiosis in Brachypodium distachyon - Meng_2021_Plant.J__
Author(s) : Meng Y , Varshney K , Incze N , Badics E , Kamran M , Davies SF , Oppermann LM , Magne K , Dalmais M , Bendahmane A , Sibout R , Vogel J , Laudencia-Chingcuanco D , Bond CS , Soos V , Gutjahr C , Waters MT
Ref : Plant J , : , 2021
Abstract : KARRIKIN INSENSITIVE2 (KAI2) is an alpha/beta-hydrolase required for plant responses to karrikins, which are abiotic butenolides that can influence seed germination and seedling growth. Although represented by four angiosperm species, loss-of-function kai2 mutants are phenotypically inconsistent and incompletely characterised, resulting in uncertainties about the core functions of KAI2 in plant development. Here we characterised the developmental functions of KAI2 in the grass Brachypodium distachyon using molecular, physiological, and biochemical approaches. Bdkai2 mutants exhibit increased internode elongation and reduced leaf chlorophyll levels, but only a modest increase in water loss from detached leaves. Bdkai2 shows increased numbers of lateral roots and reduced root hair growth, and fails to support normal root colonisation by arbuscular-mycorrhizal (AM) fungi. The karrikins KAR(1) and KAR(2) , and the strigolactone analogue rac-GR24, each elicit overlapping but distinct changes to the shoot transcriptome via BdKAI2. Finally, we show that BdKAI2 exhibits a clear ligand preference for desmethyl butenolides and weak responses to methyl-substituted strigolactone analogues such as GR24. Our findings suggest that KAI2 has multiple roles in shoot development, root system development, and transcriptional regulation in grasses. Although KAI2-dependent AM symbiosis is likely conserved within monocots, the magnitude of the effect of KAI2 on water relations may vary across angiosperms.
ESTHER : Meng_2021_Plant.J__
PubMedSearch : Meng_2021_Plant.J__
PubMedID: 34953105
Gene_locus related to this paper: bradi-i1gqp5