Abstract text: Xylogenesis is a highly coordinated developmental process including cambial cell division, cell expansion, secondary cell wall (SCW) deposition, lignification, and ultimately programmed cell death. Although secondary xylem formation plays a crucial role in both ecosystems and the global economy, the molecular mechanisms governing SCW formation remain incompletely understood.

Transcriptomic analysis during stem secondary growth development of Arabidopsis thaliana uncovered substantial changes in the expression of many genes involved in jasmonate metabolism and signaling. Among these, we identified genes encoding 2-oxoglutarate-dependent dioxygenases, known as jasmonic acid oxidases (JAO) or jasmonate-induced oxygenases (JOX), which are involved in jasmonate catabolism.

Analyses of T-DNA insertion mutants lacking JAO/JOX activity have demonstrated significant alterations in the expression of genes associated with SCW formation, including those related to lignin and other cell wall components. Ultrastructural analyses using transmission electron microscopy revealed pronounced changes in SCW architecture, including increased cell wall thickness in mutant lines compared to wild type plants.

Together, our results indicate that jasmonate catabolism plays an important role in modulating SCW formation during xylogenesis. These findings highlight jasmonate homeostasis as a regulatory component of secondary xylem formation in A. thaliana.

This work was supported by grant no. 2023/51/D/NZ9/00929 from the National Science Centre.