HopAM1 induces rosette chlorosis affecting chloroplast development and cell morphology controlled by three QTL in Col-0 × Bur-0. (A) Meristem chlorosis response following bacterial vacuum infiltration with Pto DC3000D28E(hopAM1). Col-0 exhibits strong chlorosis symptoms, while Bur-0 does not. F1 progeny exhibit mild symptoms. Chlorosis appears in newly emerging leaf and meristem in Col-0 at 10 dpi following vacuum infiltration. Chlorosis can be observed up to 21 dpi. (B) Confocal laser scanning microscopy of Arabidopsis accessions Col-0 and Bur-0 leaf tissue, harvested 14 dpi following vacuum infiltration with Pto DC3000D28E(hopAM1). Chlorophyll autofluorescence (enlarged and brightened insets with white dotted outline shown on the top left corner of respective panel) (red channel), plant cell shape (black dotted outline of cells) (green channel), and merged channels are shown for each accession. Upper and lower panels taken at equal light intensity. Bar, 10 μm. (C) CIM on 342 reannotated RILs from a Col-0 × Bur-0 collection. The x-axis displays chromosomes 1 through 5 with map distances in cM. Peak LOD scores are shown by ▾ along with their values. Effects on phenotype variation are shown as percentages for all three QTL. The global permutation level of significance was set on LOD 3.2. Bar, 50 cM.