RX2,TX2 in DUE via native USB port

To use RX1,TX1 we use Serial1.begin(), Serial1.read();
this is done via programming port

To use native USB port, we need to use SerialUSB.begin(),SerialUSB.read();

I need to use RX2,TX2 via native USB port. What should be the keyword for it? I tried Serial1USB , SerialUSB1. (Those are not defined keywords)

It's Serial2. It makes absolutely no difference whether you have your computer connected to your Due via the programming port or the native USB port.