Red leaf blotch (RLB) of almond, caused by the ascomycete Polystigma amygdalinum, is an economically important foliar disease in the Mediterranean and the Middle East almond-growing areas. This study explored the hormonal and defense-related genes responses of two almond cultivars, namely ‘Tarraco’ (highly susceptible) and ‘Mardia’ (highly tolerant), to P. amygdalinum in two complementary and independent experiments. In the first experiment (Experiment 1), asymptomatic and RLB-infected leaf samples of mature almond trees were collected in 2020 and 2023, and hormonal and defense-related genes were profiled through LC-ESI-MS/MS (Liquid Chromatography-Electrospray Ionization-Mass Spectrometry) and qPCR (real-time quantitative Polymerase Chain Reaction), respectively. Data about hormonal profiling are included in File 1, whereas those related to defense genes are included in Files 2 and 3. Relative quantification of the pathogen in symptomatic leaves of both cultivars is summarized in Files 4 and 5. A second experiment (Experiment 2) was conducted to investigate the gene expression of selected defense-related genes following periodic spraying of leaves with hormones (Salicylic Acid and Methyl-Jasmonate) and simultaneous natural exposure to RLB infection in the field. Gene expression in plants across all treatments was studied using qPCR (Files 6 and 7), and data from additional evaluations of RLB symptoms (File 8) and plant growth (File 9) were used to elucidate the effects of hormone treatment on the plant response in terms of differential gene expression, RLB incidence and severity, and plant growth. Finally, a table (File 10) summarizing the efficiency of the primer pairs used in this study to obtain corrected Cq values is included.

Additional funding information:

Agency Name: INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria) ROR: https://ror.org/011q66e29 ID: RTA2017-0009-C04-01