The relation of late blight development on potato foliage to temperature and humidity

Plant Immune Mechanisms: From Reductionistic to Holistic Points of View

“…Interestingly, adding humidity oscillation to the light/dark cycle as it occurs in nature increased the amplitude of the circadian clock, leading to better plant performance such as higher total biomass and seed weight. This ability of the plant circadian clock to sense humidity may be critical for defense against pathogen infection because high humidity in the environment is often associated with outbreaks of plant diseases (Thurston et al, 1958;Brown and Ogle, 1997;Xin et al, 2016). High humidity has been shown to induce the expression of the HrpL TF in PstDC3000, which activates the type III secretion system for the delivery of effectors into the host (Mwimba et al, 2018).…”

Daily humidity oscillation regulates the circadian clock to influence plant physiology

“…High humidity is known to correlate with disease outbreaks in plants 20 , 38 , and the outcome of an infection is determined not only by the robustness of plant immunity but also by the virulence of the pathogen 39 , 40 . We hypothesized that humidity might regulate the virulence of pathogens.…”

“…Early investigations had alluded to effects of light, temperature and air humidity on circadian clocks 10 , 11 . Yet, most studies of plant and animal circadian clocks have been conducted using only light or temperature as a clock entraining signal even though correlations between humidity changes and potential clock outputs, including metabolism 12 – 15 , animal behaviours (e.g., the biting activity of mosquitos 16 – 19 ) and incidence of plant diseases 20 , 21 have been reported. The extent to which daily humidity oscillation directly regulates the circadian clock has not been investigated.…”