title: Integrated metabolomics and transcriptomics reveal enhanced specialized metabolism in Medicago truncatula root border cells.
abstract: Integrated metabolomics and transcriptomics of Medicago truncatula seedling border cells and root tips revealed substantial metabolic differences between these distinct and spatially segregated root regions. Large differential increases in oxylipin-pathway lipoxygenases and auxin-responsive transcript levels in border cells corresponded to differences in phytohormone and volatile levels compared with adjacent root tips. Morphological examinations of border cells revealed the presence of significant starch deposits that serve as critical energy and carbon reserves, as documented through increased β-amylase transcript levels and associated starch hydrolysis metabolites. A substantial proportion of primary metabolism transcripts were decreased in border cells, while many flavonoid- and triterpenoid-related metabolite and transcript levels were increased dramatically. The cumulative data provide compounding evidence that primary and secondary metabolism are differentially programmed in border cells relative to root tips. Metabolic resources normally destined for growth and development are redirected toward elevated accumulation of specialized metabolites in border cells, resulting in constitutively elevated defense and signaling compounds needed to protect the delicate root cap and signal motile rhizobia required for symbiotic nitrogen fixation. Elevated levels of 7,4'-dihydroxyflavone were further increased in border cells of roots exposed to cotton root rot (Phymatotrichopsis omnivora), and the value of 7,4'-dihydroxyflavone as an antimicrobial compound was demonstrated using in vitro growth inhibition assays. The cumulative and pathway-specific data provide key insights into the metabolic programming of border cells that strongly implicate a more prominent mechanistic role for border cells in plant-microbe signaling, defense, and interactions than envisioned previously.
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Bonnie S
authors: BS
authors: Watson
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Mohamed F
authors: MF
authors: Bedair
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Ewa
authors: E
authors: Urbanczyk-Wochniak
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: David V
authors: DV
authors: Huhman
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Dong Sik
authors: DS
authors: Yang
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Stacy N
authors: SN
authors: Allen
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Wensheng
authors: W
authors: Li
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.).
authors: Yuhong
authors: Y
authors: Tang
authors: Samuel Roberts Noble Foundation, Plant Biology Division, Ardmore, Oklahoma 73401 (B.S.W., D.V.H., D.S.Y., S.N.A., W.L., Y.T., L.W.S.); andMonsanto Company, St. Louis, Missouri 63167 (M.F.B., E.U.-W.) lwsumner@noble.org.
authors: Lloyd W
authors: LW
authors: Sumner
mesh_terms: D001203:Ascomycota / Q000502:physiology; D005419:Flavonoids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D046913:Medicago truncatula / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D055432:Metabolomics; D008954:Models, Biological; D009586:Nitrogen Fixation; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D012231:Rhizobium / Q000502:physiology*; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D013559:Symbiosis; D059467:Transcriptome
chemical_list: D005419:Flavonoids; D010937:Plant Growth Regulators