Work

Potassium deficiency reinforces the endodermal but not the exodermal suberized barrier in maize seminal roots

Year: 2026

Type: preprint

Abstract: Potassium (K) deficiency is a widespread constraint on maize production, yet how it influences the suberized apoplastic barriers that control radial K transport in roots, and whether the endodermis and the constitutively suberized exodermis respond differently, has remained unclear. We grew maize under K deficiency in soil and across a hydroponic K gradient, with abscisic acid (ABA) and fluridone treatments, and analysed seminal roots by Fluorol Yellow 088 staining, tissue-resolved suberin chemistry of endodermis and exodermis, rubidium (Rb⁺) flux, and RNA-sequencing with weighted gene co-expression network analysis (WGCNA). K deficiency selectively increased endodermal aliphatic suberin and eliminated endodermal passage cells in soil-grown roots, whereas exodermal suberin was unchanged. Although K⁺ influx remained high, root-to-shoot Rb⁺ translocation fell sharply, consistent with K retention. A single co-expression module linked the suberin-biosynthetic genes with several K transport genes, and the suberin programme responded to exogenous ABA, indicating ABA-dependent co-regulation. Soil and hydroponic systems converged on the same endodermis-specific anatomical response. Endodermal, but not exodermal, barrier reinforcement limits K leakage from the stele in maize roots. This tissue-specific plasticity identifies the endodermal suberin biosynthesis programme, and its coordination with K⁺ uptake, as a target for improving K use efficiency. Highlight Potassium deficiency reinforces the endodermal but not the exodermal suberin barrier in maize roots, restricting root-to-shoot K translocation through an ABA-dependent programme co-regulated with K transport.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.64898/2026.09.21.753126