The Kasahara Gateway operates in two states: an open state that permits nutrient and hormone flow to fertilized seeds, promoting growth, and a closed state that blocks flow to unfertilized seeds, causing seed death.

The findings are published in Current Biology, detailing a fertilization-dependent phloem end gate that regulates seed size, with authors including Xiaoyan Liu and Ryushiro Kasahara (DOI: 10.1016/j.cub.2025.03.033).

A gene named AtBG_ppap is upregulated in fertilized hypocotyls and actively dissolves callose to keep the nutrient gateway open, with overexpression further maintaining an open gateway, boosting nutrient uptake and increasing seed size.

The discovery arose while studying callose deposition during fertilization, where researchers observed signals across the fertilization boundary and identified the rabbit-shaped tissue structure.

In rice, keeping the gateway permanently open increased seed size by about 9%, with gains up to 16.5% observed in other species, signaling significant yield potential for major crops.

The study ties fertilization success to nutrient transfer into the seed and proposes a genetic mechanism that could be harnessed in breeding to boost crop yields, with broader implications for understanding angiosperm evolution.

Researchers from Nagoya University have identified a previously unknown plant tissue, termed the Kasahara Gateway, which governs nutrient flow to seeds and marks the first new plant tissue described since the 19th century.