Updated project metadata. The SWI/SNF family of chromatin remodeling complexes is evolutionarily conserved and present in yeast, animals and plants. While the biological functions of plant SWI/SNF complexes have been studied in detail, their composition is still elusive. To clarify this picture we used protein extracts from Arabidopsis plants in vegetative phase of growth to perform a series of immunoprecipitation followed by mass spectrometry experiments, using GFP-tagged BRM ATPase as a bait. The analysis of MS data showed that the dominant form of SWI/SNF complex present in these extracts has a specific subunit composition including ARP4 and 7, SWI3C, SWP73B and BRIP2, as well as three bromodomain containing subunits, BRD1, 2 and 13. This subunit composition and the lack of the core SWI/SNF subunit BSH (SNF5/INI1) both strongly resemble the characteristics of the specific subclass of mammalian SWI/SNF complexes referred to as non-canonical BAFs, indicating that homologues of these complexes also exist in plants. We next found that depletion of the all three BRDs severely affected the assembly of this form of BRM-associated SWI/SNF complex. However, while BRD1 and BRD2 were found sufficient to allow complex formation, BRD13 was only required under BRD1/2 deficiency. The analyses of IP/MS results using BRM-GFP in different brd mutant backgrounds as well as BRD1-GFP indicate that SWI/SNF assemblies containing only one BRD isoform, BRD1 or BRD2, do exist. Furthermore, our data indicate that BRD1/2 may be necessary for the incorporation of BRIP2 subunit into the complex. Together, our results shed new light on the structural and functional diversification of SWI/SNF complexes in Arabidopsis.