Séminaire IBIP
Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 17 juillet 2025 à 14h, Amphi 206
Node-localized transporters regulate iron and zinc distribution for rice grain biofortification
Jing Che
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 211135, China
Iron (Fe) and zinc (Zn) in rice grains are crucial for both seed germination and human nutrition, yet the molecular mechanisms underlying their distribution to grains remain poorly understood. Recent studies highlight the pivotal role of rice nodes in mineral distribution. Here, we characterize three key transporters involved in Fe and Zn distribution: OsVIT2, OsVMT, and OsIET1. OsVIT2, a vacuolar Fe transporter, is highly expressed in parenchyma cell bridges, mestome sheath, and aleurone layer. Knockout of OsVIT2 reduces Fe sequestration in these tissues but increases Fe deposition in grains, enhancing Fe accumulation in polished rice without yield penalty. Similarly, OsVMT, a tonoplast-localized transporter for 2’-deoxymugineic acid (DMA), mediates vacuolar DMA storage in node I. Its disruption elevates DMA in xylem sap, solubilizing Fe and Zn, leading to 1.4–2.1-fold higher Fe, Zn, and DMA in polished grains. In contrast, OsIET1, a plasma membrane Fe efflux transporter, facilitates Fe transfer via diffuse vascular bundles in nodes. Loss of OsIET1 disrupts Fe distribution, causing Fe retention in nodes and older leaves, chlorosis in young leaves, and reduced grain yield, particularly under Fe deficiency. Collectively, these findings demonstrate that OsVIT2 and OsVMT modulate vacuolar Fe and DMA storage, respectively, while OsIET1 mediates inter-vascular Fe transfer, ensuring preferential Fe delivery to developing tissues. Disruption of OsVIT2 or OsVMT offers promising strategies for Fe/Zn biofortification without compromising yield, whereas OsIET1 is essential for maintaining Fe homeostasis and productivity.
Contact: Christian Dubos