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Auxin abolishes SHI ‐ RELATED SEQUENCE 5‐mediated inhibition of lateral root development in Arabidopsis
Author(s) -
Yuan TingTing,
Xu HengHao,
Li Juan,
Lu YingTang
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16115
Subject(s) - auxin , lateral root , primordium , arabidopsis , pericycle , mutant , microbiology and biotechnology , psychological repression , chemistry , function (biology) , wild type , biology , gene expression , biochemistry , gene
Summary Lateral roots ( LR s), which form in the plant postembryonically, determine the architecture of the root system. While negative regulatory factors that inhibit LR formation and are counteracted by auxin exist in the pericycle, these factors have not been characterised. Here, we report that SHI ‐ RELATED SEQUENCE 5 ( SRS 5) is an intrinsic negative regulator of LR formation and that auxin signalling abolishes this inhibitory effect of SRS 5. Whereas LR primordia ( LRP s) and LR s were fewer and less dense in SRS 5ox and Pro35S: SRS 5‐ GFP plants than in the wild‐type, they were more abundant and denser in the srs5‐2 loss‐of‐function mutant. SRS 5 inhibited LR formation by directly downregulating the expression of LATERAL ORGAN BOUNDARIES ‐ DOMAIN 16 ( LBD 16 ) and LBD 29 . Auxin repressed SRS 5 expression. Auxin‐mediated repression of SRS 5 expression was not observed in the arf7‐1 arf19‐1 double mutant, likely because ARF 7 and ARF 19 bind to the promoter of SRS 5 and inhibit its expression in response to auxin. Taken together, our data reveal that SRS 5 negatively regulates LR formation by repressing the expression of LBD 16 and LBD 29 and that auxin releases this inhibitory effect through ARF 7 and ARF 19.