Oxalyl-CoA synthetase acting exclusively against oxalate. No activity with malonate, succinate, malate, acetate, formate, lactate, glycolate, glyoxylate or glutarate. Required for oxalate degradation, normal seed development and defense against oxalate-producing fungal pathogens. ATP + CoA + oxalate = AMP + diphosphate + oxalyl-CoA Optimum pH is 8.0. Up-regulated upon infection with oxalate-producing fungal pathogens. Both substrate-binding domains (SBD1 and SBD2) are involved in the substrate recognition, and are sufficient to confer the substrate specificity. Decreased and delayed seed germination, but no other growth and development phenotypes. Increased sensitivity to oxalate-producing fungal pathogens. Belongs to the ATP-dependent AMP-binding enzyme family.