ABA in root endoderm behind salt growth checks
An international team of researchers led by the US Carnegie Institution (Berkley, California) have identified the mechanism that regulates root responses to high salt levels in soil and groundwater. Exposure to high salinity checks seedling lateral root growth for several days before plants recover and growth resumes. The check is due to the salt-induced upregulation of the stress hormone, abscisic acid (ABA). The researchers found that when the ABA signaling pathway was disrupted in root endoderm tissue, recovery was much faster than in wild-type plants. The gene involved, ABA insensitive 1-1, dominantly inhibits ABA signaling. It was also found that another plant hormone, the ABA antagonist giberellic acid, could also reduce saline-induced growth inhibition. The study results show that as well as acting as a filter for substances in the soil, the endodermis acts as a guard, with ABA, to prevent a plant from growing in dangerous environments, the researchers point out. Details of the study have been published in the journal, The Plant Cell.