Where is desereta Jackson of the color purple?

In Alice Walker's novel "The Color Purple," the character Celie often reflects on her sister Nettie's letters and the struggles they face. Desereta Jackson is not a primary character in the book; however, if you meant to refer to another character or a specific event related to Celie or Nettie, please clarify. The story mainly focuses on Celie's journey of self-discovery and empowerment in the early 20th-century American South.