Histone methyltransferase involved in di and tri-methylation of 'Lys-36' of histone H3 (H3K36me2 and H3K36me3). Binds to H3 already mono- or di-methylated on 'Lys-4'(H3K4me1 or H3K4me2), but not to H3K4me3. H3K4me and H3K36me represent specific tags for epigenetic transcriptional activation. Regulates positively FLC transcription to prevent early flowering transition. Required for flowering transition in response to vernalization and for the maintenance of FLC expression in late embryos, but dispensable for the initial reactivation in early embryos during reprogramming. Seems also to modulate several traits including floral organ size, root size and dormancy. Promotes apical dominance (PubMed:16299497, PubMed:10518493, PubMed:16258034, PubMed:18070919, PubMed:19915673, PubMed:20711170). Directly involved in the tri-methylation of 'Lys-36' of histone H3 (H3K36me3) at LAZ5 chromatin to maintain a transcriptionally active state of LAZ5, a TIR-NB-LRR protein involved in innate immunity (PubMed:20949080). Required for brassinosteroid (BR)-induced gene expression and histone H3 trimethylation on 'Lys-36' (H3K36me3) in BR-regulated genes (PubMed:24838002). N(6)-methyl-L-lysyl(36)-[histone H3] + S-adenosyl-L-methionine = H(+) + N(6),N(6)-dimethyl-L-lysyl(36)-[histone H3] + S-adenosyl-L-homocysteine N(6),N(6)-dimethyl-L-lysyl(36)-[histone H3] + S-adenosyl-L-methionine = H(+) + N(6),N(6),N(6)-trimethyl-L-lysyl(36)-[histone H3] + S-adenosyl-L-homocysteine Interacts with FRI and SUF4, two components of the transcription activator complex FRI-C, and with SWC6, a component of the SWR1 chromatin-remodeling complex (PubMed:20711170, PubMed:21282526, PubMed:21522130). Interacts with BZR2/BES1 and IWS1 (PubMed:24838002). Associates with centromeric constitutive heterochromatin. Ubiquitous, with higher levels in young tissues, including shoot and root apex. Expressed in ovules, tapetum layer and microspores. Not regulated by vernalization. Early flowering. Pleiotropic developmental effects including dwarf and bushy phenotype, reduced seed setting and defects in ovule and embryo sac development (PubMed:18070919, PubMed:19915673, PubMed:24838002). Altered responses to brassinosteroid (BR) (PubMed:24838002). Belongs to the class V-like SAM-binding methyltransferase superfamily. Histone-lysine methyltransferase family. SET2 subfamily. Truncated N-terminus.