Comparative transcriptome analysis of tomato cultivars pretreated with Laminarin reveals differential expression of defense-responsive genes against Early blight disease

ABSTRACT Eco-friendly measures to control disease progression are the need of the hour since chemical fungicides have been harmful to the environment. This study observed that the algal polysaccharide Laminarin triggers a defense response against early blight disease in both tolerant and susceptible tomato cultivars. A dose-dependent reduction in cell death was observed in tomato leaves pre-treated with 0.1% Laminarin and then infected with Alternaria solani in a susceptible and tolerant cultivar. As a result, 0.1% Laminarin was chosen for transcriptome analysis. Transcriptome analysis revealed the upregulation of defense-related genes, such as EF-hand domain-containing protein, Heat shock protein 70, Heat shock factor (HSF) type DNA binding domain-containing protein, Non-specific serine/threonine protein kinase, AP2/ERF domain-containing protein, Leucine-rich repeat-containing N-terminal plant type domain-containing protein, and Subtilisin-like protease. The study also validated the differentially expressed genes using qRT-PCR for bZIP, nsLTP, SKP1, and V-type ATPase genes. Overall, the study demonstrated that the algal polysaccharide Laminarin could induce defense-related genes and provide resistance against early blight disease in tomato plants. KEY MESSAGE Tomatoes defense-responsive genes showed differential expression in tolerant and susceptible cultivars when treated with laminarin, followed by Alternaria solani infection.