Role of a vacuolar iron transporter OsVIT2 in the distribution of iron to rice grains

Abstract

Iron (Fe) from rice grains is an important source of dietary intake; however, the molecular mechanisms responsible for loading of Fe to the grains are poorly understood. We functionally characterized a vacuolar iron transporter gene, OsVIT2 in terms of expression pattern, cellular localization, and mutant phenotypes. OsVIT2 was expressed in the parenchyma cell bridges of nodes, in the mestome sheath of leaf sheath and aleurone of the caryopsis. Mutation of OsVIT2 resulted in decreased Fe distribution to the leaf sheath, nodes, and aleurone, but increased Fe to the leaf blade and grains. Furthermore, Fe was heavily deposited in the parenchyma cell bridges, mestome sheath and aleurone in the wild-type rice, but this accumulation was decreased in the knockout lines. Conversely, heavier deposition of Fe was observed in the embryo and endosperm of the grains of knockout lines compared with the wild-type rice, resulting in increased Fe accumulation in the polished rice without yield penalty. These results indicate that OsVIT2 is involved in the distribution of Fe to the grains through sequestering Fe into vacuoles in mestome sheath, nodes, and aleurone layer and that knockout of this gene provides a potential way for Fe biofortification without yield penalty.

Research and Progress on the Mechanism of Iron Transfer and Accumulation in Rice Grains

“…Thus, OsYSL9 is a good target gene for bioreinforcement. In rice, regulating Fe intracellular transport by decreasing OsVIT1 or OsVIT2 expression can promote inter-tissue Fe transport from flag leaves to grains, eventually increasing the endosperm Fe concentration [118][119][120]. Fe accumulation in polished rice can be altered by regulating the stem vacuolar mugineic acid transporter gene OsVMT, which is a vacuole membrane protein responsible for DMA transport into vacuoles.…”

Remodelling of a bacterial immune system as the simple gene editing tool, Crispr-Cas, for food security and human health

“…Disrupting the vacuolar iron transporter OsVIT2 has been shown to increase iron in the rice grain. Therefore there is a potential to knock-down the OsVIT2 gene by Crispr-Cas9 (Che et al, 2021).…”

A path toward concurrent biofortification and cadmium mitigation in plant‐based foods

“…Even if plants acquire metal nutrients efficiently from the soil, a major share of them is retained in the vacuoles of root and/or vegetative shoot tissues (Ricachenevsky et al ., 2018). Knocking out transporters that sequester metals in vacuoles has increased micronutrient levels in grains (Huang et al ., 2016; Che et al ., 2019, 2021). However, under some circumstances, this brings about negative effects.…”

“…transporters that sequester metals in vacuoles has increased micronutrient levels in grains (Huang et al, 2016;Che et al, 2019Che et al, , 2021. However, under some circumstances, this brings about negative effects.…”