P-516 - Enhancing citrus defense mechanisms through herbivore-induced plant volatiles for sustainable biotic stress management

Herbivore-induced plant volatiles (HIPVs) are chemical signals emitted by plants in response to herbivore attack, triggering defense responses in neighboring plants. This study evaluates the efficacy of six HIPVs—cis-3-hexenol, cis-3-hexenyl acetate, cis-3-hexenyl butyrate, (Z)-3-hexenyl propanoate, methyl jasmonate, and methyl salicylate—in activating defense mechanisms in four citrus rootstocks: Forner-Alcaide 5, Forner-Alcaide 74, Carrizo Citrange, and Microcitrus. Plants were exposed to each volatile for 48 hours under controlled conditions, and gene expression analysis of ten defense-related genes (SAMP, PAL, LOX2, NPR1, PR2, ICS, CM, MYC2, COI, JAR1) was performed using quantitative real-time PCR. Principal component analysis revealed differential gene activation patterns, with Carrizo Citrange and Microcitrus exhibiting the strongest responses. (Z)-3-hexenyl propanoate and methyl jasmonate significantly upregulated genes involved in the jasmonate and salicylic acid pathways, with (Z)-3-hexenyl propanoate inducing a balanced activation of multiple defense pathways across all rootstocks. These findings highlight the potential of HIPVs as sustainable elicitors of plant defenses, offering an alternative to chemical pesticides. The observed variability in rootstock responses emphasizes the need for tailored HIPV-based strategies to enhance citrus resilience against biotic stressors.