Ubiquitin E3 ligase required for class I crossover (CO) formation during meiosis. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Dynamic localization on the meiotic chromosomes. Present as numerous foci on the chromosome axes and the synaptonemal complex central element until pachytene. From pachytene to diakinesis, restricted to a limited number of sites that correspond to class I crossovers. Expressed mostly in flower buds and roots. Normal vegetative growth but fertility defects leading to reduced seed number per silique, due to abortion of male and female gametophytes characterized by abnormal tetrahedral structure becoming either asymmetric tetrads or polyads containing more than four products, because of impaired class I crossover (CO) formation during meiosis.