Figure 5.
Transgeneric avirulence function of the dspEF locus and restoration of dspE mutants with the avrE locus. Norchief soybean leaves were either (A) infiltrated with 1 × 108 cfu/ml suspensions of P. syringae pv. glycinea race 4 carrying pCPP1250 (containing the dspEF locus) (Left) or pML122 (the cloning vector) and photographed after 24 hr at room temperature (Right), or (B) infiltrated with 8 × 105 cfu/ml suspensions of the same strains and photographed after 7 days at 22°C and high relative humidity. Tissue collapse is apparent on both leaves where the strain carrying pCPP1250 was infiltrated. On the leaf incubated for 7 days, chlorosis extending beyond the infiltrated area, typical of disease, is apparent on the half infiltrated with the strain carrying the vector only. The dark section on the side of the leaf infiltrated with the strain carrying pCPP1250 is a shadow caused by a buckle in the leaf. Pear halves are shown (C) 10 days after inoculation with (left to right) Ea273, Ea273dspEΔ1521(pCPP2357, containing the avrE locus), or Ea273dspEΔ1521(pCPP2357avrE∷Tn5uidA), and (B) cross-sectioned through the well 10 days after inoculation with Ea321dspEΔ1521(pCPP2357) (Left) and Ea321dspEΔ1521(pCPP2357avrE∷Tn5uidA) (Right). Although greatly reduced relative to wild type, water soaking and necrosis are apparent around and ooze can be seen within the wells of fruit inoculated with dspE strains carrying the intact avrE locus. Fruit inoculated with dspE strains carrying a disrupted clone of avrE is symptomless and shows no ooze.