Figure 8.

The proposed model of root responses in uncompacted soil and compacted soil. Compacted soil condition promotes higher ethylene response due to restricted diffusion of ethylene, leading to the accumulation of OsEIL1 in the roots. OsEIL1 directly activates YUC8 to promote auxin biosynthesis in epidermal cells, thus inhibiting root elongation. In parallel, OsEIL1 activates ABA biosynthesis in cortical cells, causing radial expansion of root cortical cells and root swelling. Increased ABA mediating OsbZIP46 activates the expression of YUC8 to promoting auxin biosynthesis, which further inhibits epidermal cell elongation and root elongation, ultimately resulting in short and swollen roots. The solid lines indicate direct interactions, the dashed lines indicate indirect interactions, the blue lines indicate regulatory relationships reported in previous studies, the red lines indicate regulatory relationships reported in this study, and the thickness of the lines indicates the strength of regulation.