Dr Gill looked after her mother following her father's death in 1999
A woman felt "as if her soul had been ripped out of her" when she found out her parents had left their £2.34m estate to the RSPCA, a court has heard.
Dr Christine Gill, from Northallerton, North Yorkshire, has started a legal battle at a High Court hearing to challenge her mother Joyce Gill's will.
Dr Gill claims her mother was coerced into making the will by her father.
She said her mother had medical conditions which affected her ability to make decisions.
Those conditions included agoraphobia and obsessive compulsive disorder, the court heard.
Opening the case, Tracey Angus, for Dr Gill, said the university lecturer devoted most of her spare time over a period of more than 30 years to voluntarily helping out at her parents' 287-acre farm.
She also bought an uninhabitable farm next door with her husband, Andrew Baczkowski, in order to be close.
Miss Angus said her client chose her job as a statistics lecturer at Leeds University because the flexibility allowed her to help at Potto Carr Farm during the holidays.
Dr Gill, 58, who is an only child, claims her parents made repeated assurances to her over the years that the farm would be left to her when they died, the court heard.
When Mr Gill died in 1999, his daughter was left to look after her mother and run the farm.
It was only when Mrs Gill died in 2006 that she saw the will, which left everything to the RSPCA.
Miss Angus said: "The discovery of the terms of the will was an immense shock to her. She described it as if her soul had been ripped out of her. Her whole life had been focused on the farm."
The lawyer told the court that Mr Gill had been described by witnesses as a "hard-working, not particularly communicative and stubborn" person.
She added: "He could also be rather domineering and was domineering towards Mrs Gill, his wife."
Miss Angus said Mrs Gill suffered from various undiagnosed conditions which meant she could not be left alone, went everywhere with her husband, hid from strangers and tuned out of conversations.
She said this meant Mr Gill would have had an influence over his wife when they wrote their wills in 1993, which left everything to each other and then to the RSPCA once they had both died.
The case continues.