Domain structures of AtLrgB protein and its role in plant cell death control. (a) Organization of the lrgAB operon in Staphylococcus aureus and the AtLrgB protein in Arabidopsis thaliana. Abbreviation: CTP, chloroplast transit peptide. (b–g) Phenotypic characterization of wild-type Arabidopsis (b,d,f) and atlrgB-1 mutants (c,e,g). Leaf sections of three-week-old seedlings (c,e) and six-week-old adult plants (g) undergoing cell death are indicated by white arrows. (h,i) Dead cells in the leaves of atlrgB-1 three-week-old seedlings are permeable to propidium iodide (PI), and fluoresce red. Chloroplasts are pseudocolored green.