Morphology of softening and translucency in the stems of tomato and eggplant seedlings due to infection by Ralstonia pseudosolanacearum F1C1

Abstract

Ralstonia pseudosolanacearum F1C1 is a soil-borne phytopathogenic bacterium with a broad host range that infects several economically important crops. This study primarily focuses on the infection of this phytopathogen in two such important crop seedlings: tomato and eggplant. The observations of the study reveal a complex set of symptoms that include drooping and blackening of the seedling stem, as well as blackening, chlorosis, and curling of cotyledon leaves. Notably, the symptom of stem softening and translucency is seen primarily in the water-submerged stem regions of the root-inoculated seedlings. Furthermore, the morphology of stem softening and translucency is more frequent in root-inoculated eggplant seedlings, underscoring a difference between tomato and eggplant seedlings regarding the virulence of the bacterium. By investigating these unique pathological phenotypes in the infected seedlings, this study uncovers unique symptoms previously not reported in seedling inoculation experiments. Such findings deepen our understanding of the complex virulence mechanisms of the pathogen. The work also highlights the distinct escape mechanisms exhibited by seedlings, revealing how some of its host plants might resist wilting despite infection, offering new avenues for future research. These findings contribute to the understanding of R. pseudosolanacearum pathogenesis, shedding light on its virulence and host response mechanisms.