title: Myrosin idioblast cell fate and development are regulated by the Arabidopsis transcription factor FAMA, the auxin pathway, and vesicular trafficking.
abstract: Crucifer shoots harbor a glucosinolate-myrosinase system that defends against insect predation. Arabidopsis thaliana myrosinase (thioglucoside glucohydrolase [TGG]) accumulates in stomata and in myrosin idioblasts (MIs). This work reports that the basic helix-loop-helix transcription factor FAMA that is key to stomatal development is also expressed in MIs. The loss of FAMA function abolishes MI fate as well as the expression of the myrosinase genes TGG1 and TGG2. MI cells have previously been reported to be located in the phloem. Instead, we found that MIs arise from the ground meristem rather than provascular tissues and thus are not homologous with phloem. Moreover, MI patterning and morphogenesis are abnormal when the function of the ARF-GEF gene GNOM is lost as well as when auxin efflux and vesicular trafficking are chemically disrupted. Stomata and MI cells constitute part of a wider system that reduces plant predation, the so-called "mustard oil bomb," in which vacuole breakage in cells harboring myrosinase and glucosinolate yields a brew toxic to many animals, especially insects. This identification of the gene that confers the fate of MIs, as well as stomata, might facilitate the development of strategies for engineering crops to mitigate predation.
authors.affiliation: Department of Botany, University of British Columbia, Vancouver V6T 1Z4, Canada.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Botany, University of British Columbia, Vancouver V6T 1Z4, Canada fred.sack@botany.ubc.ca.
authors.forename: Fred D
authors.initials: FD
authors.lastname: Sack
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002454:Cell Differentiation / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005961:Glucosinolates / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D018519:Meristem / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D054046:Plant Stomata / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D058526:Plant Vascular Bundle / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D022161:Transport Vesicles / Q000378:metabolism; D014617:Vacuoles / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D005961:Glucosinolates; D006026:Glycoside Hydrolases; D020662:Guanine Nucleotide Exchange Factors; D007210:Indoleacetic Acids; C517481:FAMA protein, Arabidopsis; C088087:GNOM protein, Arabidopsis; C511862:TGG1 protein, Arabidopsis; C511863:TGG2 protein, Arabidopsis; C022739:thioglucosidase