LEUNIG_HOMOLOG transcriptional co-repressor mediates aluminium sensitivity through PECTIN METHYLESTERASE46-modulated root cell wall pectin methylesterification in Arabidopsis.
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 METHYLESTERASE46 (PME46) 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-SLK2 complex represses the expression of PME46. The data are integrated into a model in which it is proposed that PME46 is a major inhibitor of pectin methylesterase activity within root cell walls.
The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China.
Xiaoyu
X
Geng
Institute of Plant Nutrition, Leibniz Universität Hannover, Herrenhaeuser Str. 2, Hannover, 30419, Germany.
Walter J
WJ
Horst
School of BioSciences, University of Melbourne, Victoria, 3010, Australia.
John F
JF
Golz
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, SE-901 87, Sweden.
Joanne E
JE
Lee
The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China.
Zhaojun
Z
Ding
The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, 250100, China.
Zhong-Bao
ZB
Yang
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D056970:Co-Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D010368:Pectins / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D056970:Co-Repressor Proteins; C560407:LUH protein, Arabidopsis; D012097:Repressor Proteins; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase

Arabidopsis thaliana
; LEUNIG_HOMOLOG; aluminium; cell wall; pectin; pectin methylesterification; root growth