MAMP pre-treatment compromises effector induced suppression of cROS.
The chloroplastic ROS (cROS) burst has emerged as an important component of plant immunity, as evidenced by early DC3000 effector delivery to attenuate the MTI induced cROS burst (de Torres Zabala et al. , 2015). Therefore, to assess the relationship betweenFv/Fm and cROS production and thus the role of DC3000 effectors in this process, leaves were treated with the non-specific ROS reporter, 2′7′-dichlorodihydrofluorescein diacetate (H2DCF-DA), to image cROS following DC3000 infection. Strong cROS induced following DC3000hrpA infection was evident 4.5 hpi whereas at this time cROS was minimal in DC3000 challenged leaves (Figure 3A, B). Notably, flg22 or elf18 pre-treatment of leaves prior to DC3000 infection showed cROS at 4.5 hpi (Figure 3C, D) indicating that the effectors secreted during DC3000 infection could not dampen cROS within a primed leaf.