Temporal Ethylene Dynamics in Fusarium solani-inoculated Roots of Resistant and Susceptible Dalbergia sissoo Genotypes

Abstract

The study investigates the hormonal basis of genotypic resistance in Dalbergia sissoo against vascular wilt caused by Fusarium solani by quantifying ethylene evolution trend in resistant (genotype 66) and susceptible (genotype 232) genotypes across 5, 10, 15, and 20 days after inoculation (DAI). Results revealed a highly significant three-way interaction among genotype, treatment, and day ($F(3,80) = 1934, p < .001, \eta^2_p = .986$). Under control conditions, the resistant genotype maintained a stable constitutive ethylene rate roughly 4-fold higher than the susceptible genotype. Following inoculation, the resistant genotype mounted a rapid, self-resolving ethylene burst peaking at 15 DAI (6.5-fold relative to its control) before declining by 20 DAI. Conversely, the susceptible genotype exhibited a delayed, uncontrolled surge reaching 122-fold its control value by 20 DAI with no evidence of resolution; at that final time point, its ethylene level was over 9-fold higher than that of the resistant genotype. These contrasting patterns indicate that the timing, containment, and resolution of the ethylene response—rather than its absolute magnitude—distinguish resistance from susceptibility. Ultimately, these findings identify ethylene evolution kinetics as a valuable physiological marker for early screening of Fusarium wilt resistance in D. sissoo breeding programmes.