title: HY5 is involved in strigolactone-dependent seed germination in Arabidopsis.
abstract: Strigolactones (SLs) function as plant hormones that mediate a myriad of developmental responses in higher plants. SLs also act as an environmental signal to stimulate seed germination of parasitic plant species of genera Striga and Orobanche. In contrast to their hormonal roles, genetic mechanisms of how SLs stimulate parasitic seed germination are largely not known. Recently, we established a method to monitor the germination-stimulating activity of SLs in Arabidopsis using temperature as environmental constraint (thermoinhibition). Here, we show that SLs require HY5, a key transcription factor for light signal transduction, to stimulate Arabidopsis seed germination during thermoinhibiton. Genetic analysis suggests the HY5 dependent signaling pathway is independent of other known SL signaling pathways. Thermoinhibibed seeds expressed low level of HY5 while GR24 increase the level at both mRNA and protein level. A role of SLs on activating crucial light signaling components such as HY5 may hint the evolution of parasitism associated with SL usage.
authors.affiliation: Department of Cell & Systems Biology, University of Toronto; Toronto, ON, Canada.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Toh
authors.forename: Peter
authors.initials: P
authors.lastname: McCourt
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tsuchiya
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination / Q000502:physiology*; D006358:Hot Temperature; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D008027:Light; D009687:Nuclear Proteins / Q000378:metabolism*; D031672:Orobanche / Q000235:genetics / Q000254:growth & development; D010937:Plant Growth Regulators / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012639:Seeds / Q000502:physiology; D015398:Signal Transduction; D013312:Stress, Physiological / Q000235:genetics; D034362:Striga / Q000235:genetics / Q000254:growth & development
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; C507382:GR24 compound; C109254:HY5 protein, Arabidopsis; D007783:Lactones; D009687:Nuclear Proteins; D010937:Plant Growth Regulators; D012333:RNA, Messenger