Maize yellow stripe1 encodes a membrane protein directly involved in Fe(III) uptake

Abstract

Frequently, crop plants do not take up adequate amounts of iron from the soil, leading to chlorosis, poor yield and decreased nutritional quality. Extremely limited soil bioavailability of iron has led plants to evolve two distinct uptake strategies: chelation, which is used by the world's principal grain crops; and reduction, which is used by other plant groups. The chelation strategy involves extrusion of low-molecular-mass secondary amino acids (mugineic acids) known as 'phytosiderophores' which chelate sparingly soluble iron. The Fe(III)-phytosiderophore complex is then taken up by an unknown transporter at the root surface. The maize yellow stripe1 (ys1) mutant is deficient in Fe(III)-phytosiderophore uptake, therefore YS1 has been suggested to be the Fe(III)-phytosiderophore transporter. Here we show that ys1 is a membrane protein that mediates iron uptake. Expression of YS1 in a yeast iron uptake mutant restores growth specifically on Fe(III)-phytosiderophore media. Under iron-deficient conditions, ys1 messenger RNA levels increase in both roots and shoots. Cloning of ys1 is an important step in understanding iron uptake in grasses, and has implications for mechanisms controlling iron homeostasis in all plants.

Integration of Experiments across Diverse Environments Identifies the Genetic Determinants of Variation in Sorghum bicolor Seed Element Composition

“…Originally identified in maize, the YSL proteins are a subfamily of transporters involved in metal chelate uptake, metal homeostasis, and long-distance transport (Curie et al, 2009). YSL3 is demonstrated to transport metals bound to nicotianamine (Curie et al, 2001), and in the metal hyperaccumulator Thlaspi caerulescens, YSL3 functions as an Ni-nicotianamine influx transporter (Gendre et al, 2007).…”

Iron-Binding E3 Ligase Mediates Iron Response in Plants by Targeting Basic Helix-Loop-Helix Transcription Factors

“…Under low-iron conditions, grasses such as rice (Oryza sativa) and maize (Zea mays) primarily utilize the Strategy II response, whereby they release phytosiderophores into the rhizosphere that bind to ferric iron with high affinity. Phytosiderophore-ferric iron complexes are transported into the root via membrane-localized yellow stripe and yellow stripe-like (YSL) transporters (Curie et al, 2001;Inoue et al, 2009), although several studies suggest that rice is also able to directly uptake ferrous iron (Ishimaru et al, 2006;Cheng et al, 2007).…”

iTRAQ Protein Profile Analysis of Arabidopsis Roots Reveals New Aspects Critical for Iron Homeostasis

“…Fe is acquired by two mutually exclusive mechanisms, referred to as strategy I and strategy II (Rö mheld and Marschner, 1986). In strategy II plants such as maize (Zea mays), ferric Fe is chelated by siderophores that are secreted by plant roots, and the Fe-siderophore complex is taken up by an oligopeptide transporter, YELLOW-STRIPE1 (Curie et al, 2001). Strategy II is confined to the grasses.…”