Induced systemic resistance in tomato (Solanum lycopersicum) against Botrytis cinerea by biochar amendment involves jasmonic acid signaling

The goal of this study was to identify the induced resistance pathway mediated by biochar in the tomato - Botrytis cinerea pathosystem. Tomato wild types and mutants modified in their salicylic acid (SA), ethylene (ET) or jasmonic acid (JA) metabolism were grown in a potting medium amended with biochar produced at 450 A(0)C from greenhouse wastes, to identify the possible pathway(s) involved in biochar-mediated resistance to B. cinerea. Early cellular response of H2O2 accumulation was biochemically tested, and the transcriptional changes of 12 defense-related genes upon B. cinerea challenge of detached leaflets were analyzed. Biochar amendment resulted in about 50 % reduction in B. cinerea disease severity in all tested genotypes with the exception of a JA deficient mutant, def1. Biochar amendment induced priming of early as well as late-acting defense responses particularly in the genes Pti5 (ET-related) and Pi2 (JA-related), which are known to be crucial in resistance against B. cinerea. Stronger and earlier H2O2 accumulation subsequent to B. cinerea inoculation in all genotypes was observed as a result of biochar amendment, with the exception of the def1 mutation. Biochar-mediated IR in the B. cinerea-tomato pathosystem involves the JA pathway.