STRESS INDUCED FACTOR 2 regulates arabidopsis stomatal immunity through phosphorylation of the anion channel SLAC1 ($) (Plant Cell)

Plants detect microbes by pattern recognition receptors (PRRs) that sense common conserved structures called microbe-associated molecular patterns (MAMPs) and trigger the innate immunity responses. Chan et al. identified a new player in the Arabidopsis immune response known as STRESS INDUCED FACTOR 2 (SIF2) and demonstrated that the knock-out mutant of SIF2 is more susceptible to bacteria. Upon flg22 or ABA treatment, sif2 shows impaired stomatal closure. When overexpressed, SIF2 protein increases resistance to bacteria and leads to constitutive stomatal closure. SIF2 interacts with other PRRs including FLS2 and the co-receptor BAK1, as wells as the guard cell anion channel SLAC1, a key factor in the control of osmotic pressure in guard cells. SIF2 contains a cytoplasmic kinase domain that phosphorylates SLAC1, activating its ion channel activity and promoting stomatal closure. Thus, SIF2 has a role in stomtal immunity. (Summary by Min May Wong @wongminmay) Plant Cell 10.1105/tpc.19.00578