Transcription repressor subunit of the SEU-SLK1 and SEU-SLK2 transcriptional corepressor of abiotic stress (e.g. salt and osmotic stress) response genes, by means of an epigenetic process involving histone modification (e.g. H3K9 and H3K14 acetylation), probably by recruiting HDAC, to facilitate the condensation of chromatin thus preventing transcription at the target genes (PubMed:24564815). Can also act as a transcription activator (PubMed:21518777). Implicated in embryo and floral development (PubMed:18390806). Involved in post-synthesis cell wall modifications necessary for mucilage extrusion from seeds upon imbibition, probably by promoting the expression of genes required for mucilage maturation (e.g. MUM2) (PubMed:11706181, PubMed:21362134, PubMed:21402796, PubMed:21518777). Regulates the maintenance on leaf polarity and meristem activity as well as the initiation of embryonic shoot apical meristem (SAM) development (PubMed:19837869). Forms corepressor complexes with SLK1 and SLK2; LUH is the transcription repressor subunit and SLK1 and SLK2 the specific DNA-binding adapters (PubMed:24564815). Interacts with SEU (PubMed:18390806). Binds to YAB3, YAB5 and YAB1/FIL; these complexes promote adaxial cell identity in leaves as well as embryonic shoot apical meristem (SAM) initiation and postembryonic SAM maintenance (PubMed:19837869). Expressed in roots, stems, leaves, seedlings, apex, flowers, siliques, flower organs and seeds (including seed coat). Accumulates throughout young developing leaves, before being confined to the vasculature of older leaves (PubMed:19837869). Expressed during seed coat development, reaching peak expression late in differentiation at 10 days post anthesis (DPA) (PubMed:21518777). Induced by exposures to biotic stress (e.g. nematode and Botrytis cinerea) and abiotic stress (e.g. salt, genotoxic, wounding, drought and oxidative stress). Repressed by exposures to biotic stress (e.g. Agrobacterium tumefaciens) and abiotic stress (e.g. hypoxia, cycloheximide, 2,4-dichlorophenoxyacetic acid, AgNO(3) and aminoethoxyvinylglycine). Strong defects in seed mucilage extrusion; no mucilage capsule formation and slightly irregular columellae in seeds. Altered structure of mucilage that accumulates abnormal levels of substituted rhamnogalacturonan I and methyl-esterified homogalacturonan. Increased amount of most sugars associated with an increase in methylation of the mucilage and/or primary cell wall pectins (PubMed:11706181, PubMed:21362134, PubMed:21402796, PubMed:21518777). Reduced MUM2 expression in seed coat and embryo. Shorter roots (PubMed:21402796). Enhanced tolerance to salt and osmotic stress conditions (PubMed:24564815). In plants lacking both LUG and LUH, embryo lethality and abnormal flowers (PubMed:18390806). Enhance the polarity and growth defects of luh/+ lug mutant leaves, being partially abaxialized (PubMed:19837869).