Component of the DNA topoisomerase VI involved in chromatin organization and progression of endoreduplication cycles. Relaxes both positive and negative superturns and exhibits a strong decatenase activity. The B subunit binds ATP. Involved in cell-elongation processes. ATP-dependent breakage, passage and rejoining of double-stranded DNA. Homodimer. Heterotetramer of two TOP6A and two TOP6B subunits. Interacts with SPO11-2, but not with SPO11-1, RHL1 or BIN4. Highly expressed in leaves, stems, flowers and seedlings. Plants are defective in cell elongation and show a severe dwarf phenotype. Belongs to the TOP6B family.