Barley Disease Susceptibility Factor RACB Acts in Epidermal Cell Polarity and Positioning of the Nucleus

The study demonstrated that the barley RAC/ROP protein RACB played a crucial role in cell polarity and positioning of the nucleus, rather than in regulating immune responses. Silencing RACB expression led to defects in cell polarity, affecting root hair growth and stomatal subsidiary cell development. RACB was essential for positioning the nucleus near the site of attack by the barley powdery mildew fungus (Blumeria graminis f.sp. hordei), suggesting that the fungus exploited RACB’s role in cell polarity to facilitate infection.