A node‐localized transporter OsZIP3 is responsible for the preferential distribution of Zn to developing tissues in rice

Abstract

SUMMARYDeveloping tissues such as meristem with low transpiration require high Zn levels for their active growth, but the molecular mechanisms underlying the preferential distribution to these tissues are poorly understood. We found that a member of the ZIP (ZRT, IRT-like protein), OsZIP3, showed high expression in the nodes of rice (Oryza sativa). Immunostaining revealed that OsZIP3 was localized at the xylem intervening parenchyma cells and xylem transfer cells of the enlarged vascular bundle in both basal and upper nodes. Neither OsZIP3 gene expression nor encoded protein was affected by either deficiency or toxic levels of Zn. Knockdown of OsZIP3 resulted in significantly reduced Zn levels in the shoot basal region containing the shoot meristem and elongating zone, but increased Zn levels in the transpiration flow. A short-term experiment with the 67 Zn stable isotope showed that more Zn was distributed to the lower leaves, but less to the shoot elongating zone and nodes in the knockdown lines compared with the wild-type rice at both the vegetative and reproductive growth stages. Taken together, OsZIP3 located in the node is responsible for unloading Zn from the xylem of enlarged vascular bundles, which is the first step for preferential distribution of Zn to the developing tissues in rice.

OsHKT1;5 mediates Na+ exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice

“…(b) Expression of OsHKT1;5 in vasculatures of node I and the basal stem is shown. RNA samples were prepared from enlarged vascular bundles (EBVs) and diffuse vascular bundles (DVBs) of node I using the laser microdissection (LMD; Sasaki et al ., ; Suzuki et al ., ) as well as the basal stem (BS). Relative OsHKT1;5 expression in each part is shown setting its expression in the EVB to 1 ( n = 5–8, ±SD).…”

Bioimaging of multiple elements by high‐resolution LA‐ICP‐MS reveals altered distribution of mineral elements in the nodes of rice mutants

“…Two node‐localized Zn transporters, OsZIP3 and OsHMA2, play pivotal roles in this preferential distribution. OsZIP3 is localized in the marginal region of xylem of EVBs and is responsible for the xylem unloading of Zn at each node (Sasaki et al ., ). OsHMA2 is mainly localized to the phloem of DVBs and is responsible for the phloem re‐loading of Zn (Yamaji et al ., ).…”

Genome-Wide Association Study Reveals Novel Marker-Trait Associations (MTAs) Governing the Localization of Fe and Zn in the Rice Grain

“…Initially, it was reported that the cation transporter proteins ZIP1 and ZIP3 might be involved in the uptake of Zn from soil (Ramesh et al, 2003;Bashir et al, 2012). Subsequently, Sasaki et al (2015) observed that OsZIP3 is localized in the nodes, and they further demonstrated that the OsZIP3 protein is responsible for unloading the Zn from the xylem of enlarged vascular bundles in nodes. In addition to these vital candidate genes, 7 of the 29 MTAs were within the intervals of previously mapped QTLs ( Table 3).…”