Genetic Modulation of ROS Scavenging by DgNAC3 Improves Cold Stress Tolerance in Chrysanthemum morifolium

Area of Science:

• Plant Biology
• Molecular Genetics
• Stress Physiology

Background:

• The NAC transcription factor family is crucial for plant low-temperature stress responses.
• Regulatory mechanisms of NAC transcription factors in cold stress tolerance are not fully understood.
• Chrysanthemum (Dendranthema grandiflorum) is a commercially important ornamental plant susceptible to cold.

Purpose of the Study:

• To investigate the role of the low-temperature-induced gene DgNAC3 in chrysanthemum cold stress resistance.
• To characterize the function of DgNAC3 in modulating physiological and molecular responses to cold.

Main Methods:

• Isolation and characterization of the DgNAC3 gene from chrysanthemum 'Jinba'.
• Generation of transgenic chrysanthemums overexpressing DgNAC3.
• Assessment of physiological parameters (wilting, survival rates, reactive oxygen species levels) and gene expression under low-temperature stress.

Main Results:

• Overexpression of DgNAC3 significantly improved cold tolerance in transgenic chrysanthemums, reducing wilting and increasing survival rates.
• Transgenic lines exhibited reduced levels of malondialdehyde (MDA), hydrogen peroxide (H2O2), and superoxide anion (O2-).
• Activities of antioxidant enzymes (CAT, SOD, POD) and expression of related genes (DgPOD, DgCAT, DgCu/ZnSOD) were significantly elevated in transgenic lines.

Conclusions:

• DgNAC3 plays a vital role in enhancing chrysanthemum cold stress resistance.
• Overexpression of DgNAC3 improves cold tolerance by enhancing the scavenging of reactive oxygen species (ROS) and boosting antioxidant defense systems.
• DgNAC3 is a potential target gene for developing cold-hardy chrysanthemum varieties.