摘要Plant root hairs are essential for mineral and water absorption,which possess sophisticated sensory mechanisms to allow them to respond to different environmental signals.Ammonium(NH4+)is a major form of nitrogen in the soil.NH4+can influence the root system architecture,such as root hair growth(Liu and von Wirén,2017).Un-derstanding the role of NH4+in regulating root hair growth would be helpful for improving plant nutrient use efficiency.We previously demonstrated that[Ca2+]cyt-assosiated protein kinase 1(CAP1),a member of the Catharanthus roseus receptor-like kinase 1-like sub-family,regulates NH4-related root hair growth(Bai et al.,2014a;Bai et al.,2014b).The deficiency of CAP1 caused a loss of tip-focused cytoplasmic Ca2+and reactive oxygen species(ROS)gradi-ents,ultimately stunting root hair growth.The inhibited root hair growth of the cap1-1 mutant was restored by depleting NH4+from the growth medium(Bai et al.,2014a).However,the interplay be-tween CAP1 and NH4+has not yet been elucidated in detail.