Brachypodium distachyon as a new model system for understanding iron homeostasis in grasses: Phylogenetic and expression analysis of Yellow Stripe-Like (YSL) transporters

Burcu K. Yordem, Sarah S. Conte, Jian Feng Ma, Kengo Yokosho, Kenneth A. Vasques, Srinivasa N. Gopalsamy, Elsbeth L. Walker

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Background and AimsBrachypodium distachyon is a temperate grass with a small stature, rapid life cycle and completely sequenced genome that has great promise as a model system to study grass-specific traits for crop improvement. Under iron (Fe)-deficient conditions, grasses synthesize and secrete Fe(III)-chelating agents called phytosiderophores (PS). In Zea mays, Yellow Stripe1 (ZmYS1) is the transporter responsible for the uptake of Fe(III)PS complexes from the soil. Some members of the family of related proteins called Yellow Stripe-Like (YSL) have roles in internal Fe translocation of plants, while the function of other members remains uninvestigated. The aim of this study is to establish brachypodium as a model system to study Fe homeostasis in grasses, identify YSL proteins in brachypodium and maize, and analyse their expression profiles in brachypodium in response to Fe deficiency.MethodsThe YSL family of proteins in brachypodium and maize were identified based on sequence similarity to ZmYS1. Expression patterns of the brachypodium YSL genes (BdYSL genes) were determined by quantitative RTPCR under Fe-deficient and Fe-sufficient conditions. The types of PS secreted, and secretion pattern of PS in brachypodium were analysed by high-performance liquid chromatography.Key ResultsEighteen YSL family members in maize and 19 members in brachypodium were identified. Phylogenetic analysis revealed that some YSLs group into a grass-specific clade. The Fe status of the plant can regulate expression of brachypodium YSL genes in both shoots and roots. 3-Hydroxy-2′- deoxymugineic acid (HDMA) is the dominant type of PS secreted by brachypodium, and its secretion is diurnally regulated.ConclusionsPS secretion by brachypodium parallels that of related crop species such as barley and wheat. A single grass species-specific YSL clade is present, and expression of the BdYSL members of this clade could not be detected in shoots or roots, suggesting grass-specific functions in reproductive tissues. Finally, the Fe-responsive expression profiles of several YSLs suggest roles in Fe homeostasis.

Original languageEnglish
Pages (from-to)821-833
Number of pages13
JournalAnnals of Botany
Volume108
Issue number5
DOIs
Publication statusPublished - Oct 2011

Keywords

  • Brachypodium distachyon
  • YS1
  • YSL
  • Yellow Stripe-Like
  • Zea mays
  • iron homeostasis
  • nicotianamine
  • phytosiderophore

ASJC Scopus subject areas

  • Plant Science

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