The p' polymorphism has been introduced into ref(2)P+++.O1.cCMa. The p' polymorphism consists of amino acid residue Q43 being replaced by a L residue.
ref(2)P++p'.O1.cCMa is permissive for sigma virus multiplication.
ref(2)Pod3/Df(2L)E55 males carrying ref(2)P++p'.O1.cCMa are fertile.