Fragment containing the ref(2)Po1 transcription unit.
ref(2)P+++.O1.cCMa is permissive for sigma virus multiplication.
ref(2)P+++.O1.cCMa rescues ref(2)Pod3/Df(2L)E55
ref(2)Pod3/Df(2L)E55 males carrying ref(2)P+++.O1.cCMa are fertile.