Chlorophyll a Fluorescence: A Method of Biotic Stress Detection

Abstract

Plant diseases are a major threat to food security, causing drastic alterations in plant metabolism upon infection by pathogens. This often results in decreased biomass accumulation, slowed growth rates, and diminished yield components. Pathogens, through various lifestyles such as biotrophic, necrotrophic, and hemibiotrophic, disrupt photosynthesis, the primary metabolic process, via functional and structural damages. Furthermore, the CO2 assimilation in plants is severely altered by pathogens regardless of their lifestyles. Photosynthetic determinations allow us to establish a perspective about the physiological impairment caused by pathogens related to alterations in the CO2 flow from the atmosphere to carboxylation sites, stomatal limitations, and photosynthetic performance of photosystem II (PSII). From the changes in the energy, dissipation is possible to establish the functional status of the photochemistry machinery under stress conditions. For the above, chlorophyll a fluorescence (CF) and CF imaging (CFI) arose as a method highly sensible to determine the damage caused by pathogens in plants. This review shows a practical perspective on CF tools using visual method and rapid fluorescence induction kinetics (OJIP-test), for disease detection associated with plant-pathogen interaction studies from the physiological viewpoint, their implications for plant pathology research, applications for the plant phenotyping field, and biotic stress detection.