• The root barrier to radial O₂ loss (ROL) is a key root trait preventing O₂ loss from roots to anoxic soils thereby enabling root growth into anoxic, flooded soils.
• We hypothesized that the ROL barrier can also prevent intrusion of hydrogen sulphide (H₂S), a potent phytotoxin in flooded soils. Using H2S and O₂-sensitive microsensors, we measured the apparent permeance to H₂S of rice roots and tested whether restricted H₂S intrusion reduced its adverse effects on root respiration and if H₂S could induce the formation of a ROL barrier.
• The ROL barrier reduced apparent permeance to H₂S by almost 99%, greatly restricting H₂S intrusion. The ROL barrier acted as a shield towards H₂S; O₂ consumption in roots with a ROL barrier remained unaffected at high H₂S concentration (500 µM), compared to a 67% decline in roots without a barrier. Importantly, low H₂S concentrations induced the formation of a ROL barrier.
• In conclusion, the ROL barrier plays a key role in protecting against H₂S intrusion, and H₂S can act as an environmental signalling molecule for the induction of the barrier. The study demonstrates the multiple functions of the suberized/lignified outer part of the rice root beyond that of restricting ROL.

Please see the README document and the accompanying published article (open access):

The barrier to radial oxygen loss protects roots against hydrogen sulphide intrusion and its toxic effect

Lucas León Peralta Ogorek, Hirokazu Takahashi, Mikio Nakazono, Ole Pedersen

First published: 16 March 2023 (https://doi.org/10.1111/nph.18883)