Scott Morrison has unveiled his new-look ministry, breaking his commitment to retain Melissa Price as environment minister and replacing her with Sussan Ley.

Morrison said Price had “asked for a new challenge” and would now serve as defence industry minister.

Ley will be one of a record seven women in cabinet, including the first ever female agriculture minister, Bridget McKenzie.

Morrison has given the energy minister, Angus Taylor, responsibility for emissions reduction, telling reporters in Canberra he will be responsible for “meeting the 2030 emissions targets”, suggesting a role beyond the electricity sector.

Barnaby Joyce has lost his role as special drought envoy, with responsibility for drought transferred to the water resources minister, David Littleproud, who remains in cabinet and adds rural finance, natural disaster and emergency management to his title but loses agriculture to McKenzie.

A tweet from Joyce suggested he had only learnt he had lost the role via Sky News.

Just found out from you guys then — Barnaby Joyce (@Barnaby_Joyce) May 26, 2019

Mark Coulton gains McKenzie’s old portfolios of local government and decentralisation but overall the Nationals go backwards from five cabinet representatives to four.

Morrison ally Stuart Robert is one of the big winners from the reshuffle, entering cabinet as minister for government services with responsibility for the National Disability Insurance Scheme.

Another key Morrison ally, Alex Hawke, becomes the minister for the Pacific and international development and assistant defence minister. As flagged before the election, Linda Reynolds is the new defence minister.

Marise Payne will become minister for women, in addition to retaining foreign affairs, while Ken Wyatt will become the first Indigenous cabinet minister in Australia’s history, as the new minister for Indigenous affairs.

In addition to vacancies created by the retirement of senior ministers including Kelly O’Dwyer and Nigel Scullion, Morrison created room in cabinet by offering Mitch Fifield the role of ambassador to the United Nations and Arthur Sinodinos ambassador to the US.

Paul Fletcher becomes the minister for communications, cyber safety and the arts, while Anne Ruston will join cabinet as the minister for family and social services. Luke Howarth was promoted to assistant minister for community housing.

Michaelia Cash will remain in cabinet, responsible for employment, skills, small and family business, but industrial relations will shift to Christian Porter, who remains the attorney general and becomes manager of government business in the lower house.

Morrison Government Ministry List - 26 May 2019 #auspol pic.twitter.com/G7hy25xG1c — Political Alert (@political_alert) May 26, 2019

Richard Colbeck will serve as minister for aged care, senior Australians, youth, and sport.

Trevor Evans was appointed assistant environment minister and Warren Entsch is the special envoy for the Great Barrier Reef.

Michael Sukkar will return as minister for housing and assistant treasurer, while Jane Hume was promoted to assistant minister for superannuation and financial services

Mathias Cormann retains finance and gains responsibilities of the special minister of state. Greg Hunt remains health minister but will also gain responsibility for the public service.

Morrison said the two Senate vacancies would be filled by the New South Wales and Victorian divisions of the Liberal party.

The vacancy would allow the Liberal Party to return conservative Jim Molan – who conducted a below the line insurgent campaign to upend the NSW Senate ticket order – to the Senate without displacing a National.

Molan told Guardian Australia that Sinodinos would be “absolutely superb” as ambassador to the US, but denied he had lobbied for a vacancy, claiming he is still in the running for the sixth Senate seat in NSW.

Joe Hockey’s term as ambassador to the US is due to expire at the end of the year.