The octadecanoid signaling pathway participates in the chilling-induced transcription of ω-3 fatty acid desaturases in Arabidopsis

The jasmonate signaling pathway is known to be involved in various stress responses in plants, but little is known specifically on the role of the octadecanoid pathway in the regulation of ω-3 fatty acid desaturase (FAD) genes in response to low temperature. To uncover this problem, the expression level of three ω-3 FAD genes (AtFAD3, AtFAD7, and AtFAD8) and the content of linolenic acid (C18:3) in both wild type (WT) and mutant (or WT suppressed) plants disrupted in the octadecanoid pathway were analyzed under normal conditions and the chilling treatment (4 °C), respectively. As compared with WT plants, chilling-induced organ-specific expressions of ω-3 FAD genes significantly changed when the octadecanoid pathway was blocked or suppressed, and presented either the “suppressed increase” or the “enhanced decrease” tendency. Meanwhile, chilling-induced increases in the content of C18:3 found in WT plants, obviously reduced in both leaves and roots, and even turned to a decrease in stems when the octadecanoid pathway was disrupted. Overall, the transcription of ω-3 FAD genes and the proportion of C18:3 in the whole plant both of aos mutants and salicylic acid (SA)-treated plants under chilling stress were evidently lower than those of WT plants, except the expression of AtFAD3 gene in leaves. All these findings indicate that the octadecanoid pathway does participate in the chilling-induced transcription of ω-3 FAD genes in Arabidopsis.