Transcription activator that regulates the expression of at least NAI2, PYK10 and PBP1. Required for and mediates the formation of endoplasmic reticulum bodies (ER bodies). Involved in the symbiotic interactions with the endophytes of the Sebacinaceae fungus family, such as Piriformospora indica and Sebacina. Homodimer. Expressed constitutively in roots, leaves, stems, and flowers.