# Osaka Metropolitan University: boron moves inward in Arabidopsis roots via uniform BOR3 transporter

- Published: 2026-11-08 05:43 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: boron transport in plants, BOR3 transporter, diffusive alliance transport, Arabidopsis thaliana roots, apoplast diffusion, polar localization of transporters, boron deficiency, Plant Physiology
- URL: https://realtech.media/news/rt-d2b280e1478981650bb2b3e8_osaka_metropolitan_university/

**In Arabidopsis thaliana roots, boron flows inward via BOR3, which is not polarly localized, together with diffusion in the apoplast. The authors call the mechanism diffusive alliance transport.**

![Osaka Metropolitan University: boron moves inward in Arabidopsis roots via uniform BOR3 transporter](https://realtech.media/media/2026/11/dff7445ff9c5e4f9.jpg)
*A4ernyh, Wikimedia Commons, CC BY-SA 4.0*

Researchers at Osaka Metropolitan University have described a mechanism by which boron moves inward through plant roots without a transporter concentrated on one side of the cell, according to EurekAlert. The study, published in Plant Physiology, was done on the model plant Arabidopsis thaliana and led by Naoyuki Sotta, assistant professor at the university's Graduate School of Agriculture. [1]

Boron is essential for plant growth. Its deficiency can inhibit the expansion of young leaves, reduce root elongation and impair fertility. In most plants boron is transported mainly through the xylem, a one-way pathway from roots to leaves. It had traditionally been thought that such directional transport requires polar localization of transporters, meaning their concentration on one side of the cell. [1]

## BOR3 without polarity

The team studied the boron transporter BOR3 using gene analysis, physiological experiments and mathematical modeling. The related transporters BOR1 and BOR2 are well characterized, while the function of BOR3 had remained unclear. Plants lacking BOR1, BOR2 and BOR3 had significantly shorter roots than plants lacking only BOR1 and BOR2, which indicates a role for BOR3 in boron uptake and transport through the roots. [1]

Unlike BOR1 and BOR2, which sit unevenly in root-cell membranes in a way that supports movement in one direction, BOR3 is not noticeably polarized. According to Sotta, it is distributed largely uniformly on the plasma membrane. [1]

## Diffusive alliance transport

Modeling of boron movement through root tissues pointed to a combination of apolar and polar processes. The authors call the mechanism diffusive alliance transport (DAT). It relies on the interplay between membrane transporters and diffusion through the apoplast, the network of spaces outside plant cells, including cell walls and intercellular spaces. [1]

Through polarly localized channels, boron first accumulates in the apoplast next to one cell and then diffuses into a neighboring inner cell. There BOR3 exports it into the surrounding apoplast on both sides of the cell. This raises boron levels in the more internal apoplastic compartment and creates a concentration difference between neighboring compartments. Repeated from cell to cell, the process produces a net inward flow of boron, so higher concentrations build up deeper inside the root. [1]

The team plans to investigate whether DAT operates in other biological transport systems and how the mechanism works in more complex tissues. [1]

## Sources

1. [EurekAlert](https://www.eurekalert.org/news-releases/1150376)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-d2b280e1478981650bb2b3e8_osaka_metropolitan_university/