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LEUNIG _ HOMOLOG transcriptional co‐repressor mediates aluminium sensitivity through PECTIN METHYLESTERASE 46 ‐modulated root cell wall pectin methylesterification in Arabidopsis
Author(s) -
Geng Xiaoyu,
Horst Walter J.,
Golz John F.,
Lee Joanne E.,
Ding Zhaojun,
Yang ZhongBao
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13506
Subject(s) - pectin , cell wall , arabidopsis , repressor , mutant , chemistry , methylation , gene , cell , biochemistry , f box protein , gene expression , microbiology and biotechnology , biology , ubiquitin ligase , ubiquitin
Summary A major factor determining aluminium (Al) sensitivity in higher plants is the binding of Al to root cell walls. The Al binding capacity of cell walls is closely linked to the extent of pectin methylesterification, as the presence of methyl groups attached to the pectin backbone reduces the net negative charge of this polymer and hence limits Al binding. Despite recent progress in understanding the molecular basis of Al resistance in a wide range of plants, it is not well understood how the methylation status of pectin is mediated in response to Al stress. Here we show in Arabidopsis that mutants lacking the gene LEUNIG _ HOMOLOG ( LUH ), a member of the Groucho‐like family of transcriptional co‐repressor, are less sensitive to Al‐mediated repression of root growth. This phenotype is correlated with increased levels of methylated pectin in the cell walls of luh roots as well as altered expression of cell wall‐related genes. Among the LUH ‐repressed genes, PECTIN METHYLESTERASE 46 ( PME 46 ) was identified as reducing Al binding to cell walls and hence alleviating Al‐induced root growth inhibition by decreasing PME enzyme activity. seuss‐like2 ( slk2 ) mutants responded to Al in a similar way as luh mutants suggesting that a LUH – SLK 2 complex represses the expression of PME 46 . The data are integrated into a model in which it is proposed that PME 46 is a major inhibitor of pectin methylesterase activity within root cell walls.