Lipoxygenase 2 (LOX2) enhances cold tolerance through modulating jasmonate biosynthesis in Nicotiana tabacum.

BACKGROUND

Chilling stress severely compromises tobacco production by reducing leaf biomass accumulation and deteriorating leaf quality. Lipoxygenase (LOX) plays a key role in the oxidative metabolism of linoleic and linolenic acids, which serves as the initial step for jasmonic acid (JA) biosynthesis. However, its specific function in mediating cold-induced JA accumulation and cold tolerance in Nicotiana tabacum remains elusive.

RESULTS

Our results found that cold stress significantly induces NtLOX2 expression in N. tabacum. Transgenic tobacco plants overexpressing NtLOX2 (OE#NtLOX2-1 and OE#NtLOX2-2) exhibited improved cold tolerance, which was associated with increased activities of antioxidant enzymes and improved reactive oxygen species (ROS) scavenging capacity. RNA-seq analysis revealed that NtLOX2-overexpressing lines displayed upregulation of key cold-responsive genes, including COR, ERF, LRR-RLK, GST, POD, DREB, and NCED. Furthermore, genes involved in JA biosynthesis, such as ADH and OPR1, were also upregulated, concomitant with elevated levels of both JA and MeJA as confirmed by metabolic profiling.

CONCLUSIONS

Our results demonstrate that NtLOX2 enhances cold tolerance by stimulating JA biosynthesis and activating a downstream transcriptional network of cold-responsive and antioxidant genes. These findings posit NtLOX2 as a promising genetic target for improving cold tolerance in crops.