Dara Calleary has been nominated as the new Minister for Agriculture, Food and the Marine.
The Mayo TD and deputy Fianna Fáil leader had initially been appointed as Chief Whip.
Jack Chambers has now been named the new Government Chief Whip, while Sean Fleming has been promoted to Junior Minister in the Department of Finance.
It comes as Micheál Martin faced increased scrutiny in the Dáil over his sacking of Barry Cowen last night.
Martin defended voting down proposals yesterday afternoon that would have brought Deputy Cowen into the Dáil to answer questions on his drink driving offence.
The Taoiseach said he wanted Barry Cowen to do so voluntarily, and when he refused to do so he was sacked.
Micheál Martin said he gave Deputy Cowen every chance to address the issue.
He told the Dáil: "I had come into the House after having asked Deputy Cowen to consider his position and reflect on his decision not to come into the House.
"In my view he should have come into the House. I was giving him time and space to reflect on that.
"When he still refused to respond to my view that he should come into the House... I was left with no alternative then."
