Figure 3.

Lesion Phenotypes and Bacterial Growth in Wild-Type and vad1 Plants after Pathogen Inoculation.

Leaves of 5-week-old wild-type and vad1 mutant plants grown under lesion-promoting conditions ([A] and [B]) were infiltrated on both sides of the leaf with suspensions (2.10⁷ colony-forming units [cfu]/mL) of P. syringae pv tomato strain DC3000 expressing avrRpm1 (A) and DC3000 (B). Leaves were photographed 54 h after inoculation and were classified according to the propagation rate of the lesions before inoculation: no lesion (vad1⁻), presence of lesion only halfway up the primary vein (vad1⁺), and lesions propagating along the whole primary vein (vad1⁺⁺). In the case of DC3000, inoculations with a lower inoculum (2.10⁵ cfu/mL) were performed for a better observation of the disease phenotypes in the wild-type and vad1⁺ leaves. All treatments were repeated at least three times with similar results.

(C) Growth of P. syringae pv tomato DC3000 and DC3000 expressing avrRpm1 in wild-type and vad1 plants grown under lesion-promoting conditions or lesion⁻ conditions. In the case of mutant plants grown under lesion-promoting conditions, bacterial growth was evaluated in the different leaves classified as previously described. Inoculation was performed with a bacterial suspension of 2.10⁵ cfu/mL, and bacterial growth determinations were performed at the times indicated. Mean bacterial densities are shown (three to five replicates with corresponding standard deviations) for one representative experiment from two or three independent experiments performed for each strain.